FT-101ZD SG4

FT-101ZD SG4
Survival Guide
Version 4 Updated spring 2016
This manual was downloaded from Fox Tango International
FT-101Z MK0
This manual was downloaded from Fox Tango International
Yaesu FT-101Z/ZD series transceiver
Yaesu FT-101ZD page
Presented by:
Fox Tango International
The FT-101 history
The original Yaesu FT-101 series transceivers, produced in 1970-1978 in ever increasing numbers were a very good
alternative for the very expensive American made receivers and transmitters of the time.
They were full of useful options, for which you had to pay much $$$ extra (if available) in other ham equipment.
Build like a battleship, with a modular construction, it was easy to repair, and the big numbers which are still around,
prove the sound work of the Yaesu engineers at the time.
The FT-101 series was very successful, and there were many versions of it, starting with the FT-101, released in 1970 to
the FT-101F, who was released in 1978. See the FT-101 page on the FoxTang website for more information for the FT-101
series of transceivers.
The Yaesu FT-101ZD was brought on the market in 1979, as a low-cost alternative for the FT-901ZD, which is the real
descendant of Yaesu’s famous FT-101 series of transceivers.
As Yaesu already had a very good reputation for performance and durability, it is no wonder that the new series
transceivers became very popular in the ham community, special in Europe, because the high $$$ price of the available
American equipment and the high import taxes on them, and the fact that there where almost no agents prohibited a
broad distribution of American equipment. I still think the American industry at the time missed a chance here.
Only Heathkit had a representative over here, and was very popular at the time for their nice kits.
Yaesu had a small sales network in Europe and the Swiss firm Sommerkamp imported the same sets under their own
typenumbers and under the name Sommerkamp, they were a big success in Italy and Germany.
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The FT-101Z/ZD
In 1979 Yaesu announced a new version of the FT-101, called the FT-101Z (analog dial) and ZD, (with digital dial).
The FT-101ZD looked very much like the FT-901, but had a simpler internal construction with just a couple of plug-in boards
for HF, premixer and oscillator. The IF and the audio board, were connected with plugs from a wire harnass, the power supply
boards are soldered direct to the wire harnass, thus not the overall modular construction that made the older FT-101 and
new FT-901 so popular.
Altough the construction of the FT-101ZD was simpler, the transceiver was packed with useful features, that appealed to
many hams, (including myself, I bought one in 1979, and still use it almost daily,).
It had a very sensitive receiver, SSB and CW modes, a digital display, very liniair VFO, smooth tuning, a good set of filters, a
PA with real transmitting tubes (6146B’s), speech processor, IF shift with passbands between 300hz and 2.4khz, a clarifier,
a calibrator and a noise blanker, making it a very complete package for a very reasonable price. Later models had also AF
notch/peak filters, WARC bands and AM/FM capability. There were outputs for connection to a transverter and liniar amplifier,
inputs for a second VFO and phone patch. It was one of the best buys you could made at the time.
The FT-901 had even more bells & whistles, but had also a $ 1000 higher pricetag.
The transceiver is very well build, with good quality components, and, if used normally, will last forever. Weight is in excess
of 15 kg, due the built-in power supply, giving it the feel of a battleship.
The powersupply can be fed from 100/110/117 or 200/220/235 Volts 50/60hz, and with the optional switching unit, even
from 13.8 Vdc, altough you need a heavy-duty car battery. (current in voice peaks around 20 Amps).
Analog model FT-101Z
FT-101ZD MK1
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Specifications FT-101Z, FT-101ZD:
Frequency Range:
RF Power output:
Image rejection:
Current drain DC:
Amateur HF transceiver
50 – 75 ohms,
15 kilograms
1979 – 1982
(early models had no WARC bands)
(later models also AM or FM)
0.25 uV (10db S/n)
0.5 uV (10db S/n)
2.4 khz @ -6db,
4 khz @ -60db
600 or 300 hz, (optional)
- 60 db (160-15m)
- 50 db (10m)
analog dial
analog + digital dial
100-235 V ac 50/60hz
5.5 Amps,
13.8 Vdc option
1.1 Amps with heater off)
Max. 21 Amps.
SO-239 connector
345 * 157 * 326 mm (W*H*D)
external VFO
external scanning VFO (only for the Mk3)
Linear Amplifier 1200W SSB, 1000W CW
External Speaker/Phone Patch
Antenna Coupler
The FT-101ZD is updated several times during its lifetime, and there are in fact 4 different types, using the same designator.
By the introduction in 1979, the transceiver had only SSB and CW, later there was a AM (tx/rx) option, still later the Warc
bands were introduced, and the last version had it all, including a optional AM or FM board, and Audio notch/peak filter.
The later models have more features, so they are more in demand, and are normally higher priced in auctions or on the
internet. It seems difficult to see what the difference is between the first and last models because there is not much changed
on the front.
Fortunately there is a easy way to see at a glance the difference between the various models, the only thing you need to
know is the serial number of the set.
The Yaesu serial number on the back of the set consists of a number, a letter and 6 numbers:
The first number is the year of production:
The letter is the production month:
The next 2 numbers are the production run:
The next 4 numbers are the serial numbers:
9=1979, 0=1980, 1=1981 a.s.o.
C=jan D=feb E=march a.s.o.
from 01 (first series) to 30 and higher (last series)
from 0001 to 9999
Identification of the model is easy by the use of the production run:
FT-101Z/ZD MK0
Production run:
160-10m, SSB/CW, only, WWV rx-only, aux
01 – 07, all in 1979
FT-101Z/ZD MK1
Production run:
160-10m, SSB/CW/AM, WWV rx-only, aux
Only Run 16 has the new type counter.
08 – 16
FT-101Z/ZD MK2
Production run:
160-10m + WARC, SSB/CW/AM
17 – 23
FT-101Z/ZD MK3
Production run: 24 – 30 and up.
160-10m + WARC, SSB/CW/AM or FM
The last serie is also easely identified by the grey and silver knobs on the front.
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The MK0 model has SSB and CW
only, and covers the bands
160,80,40,20,15 and 10m.
The MK1 model has SSB, CW and
AM , and covers the bands
160,80,40,20,15 and 10m.
The MK2 model has SSB, CW and
AM and covers the bands
160,80,40,30,20,17,15,12 and 10m.
Differences between the Mk0/1/2/3
The MK3 model has SSB, CW and
AM or FM and covers the bands
160,80,40,30,20,17,15,12 and 10m.
The switchboard in all models of the
FT-101ZD has the same functions,
but in the MK0, MK1 and MK2 models
they have black tumblers, in the Mk3
they have silver tips, fitting by the
silver rings on the knobs.
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All models have a width control for
varying the passband of the IF
filter(s), the MK3 has additional a
audio APF/Notch filter.
The Bandswitch of the MK0 and MK1 have 11 positions for the standard amateurs bands 160, 80, 40, 20, 15, 10m, a
receive only position for 5 - 5.500 Mhz, and a position for a optional band. The MK2 and MK3 bandswitch has 12
positions for the 160, 80, 40, 30, 20, 17, 15, 12 and 10M bands, so includes the WARC bands.
The Preselector and the Plate tuning have in the MK0 and MK1 positions for the “old” hambands, in the MK2 and MK3
they have also positions for the WARC bands that overlap here and there.
All three models have a clarifier, wich allows tuning of +/- 5 khz around the original frequency, just enough for splitfrequency DX work, or for round-table QSO’s, if one of the members is not spot-on the frequency. The clarifier can be
used in receive or transmit mode, or both.
In the MK3 model ( here on the right) there is also a Squelch knob for use with the optional FM board.
Optional CW Filter
In the FT-101ZD, a CW filter is an option, and can easely be installed
on the IF board. The normal CW filter has a bandwith of 600 hz. Later
there was also a filter of 300hz, but using this filter, there is a
serious loss of signal, both on receive and transmit, because the
smaller bandwith.
The FT-101Z story
The FT-101Z was the budget version of the FT-101ZD, with a nice and
surprisingly exact mechanical dial instead of a digital dial, but otherwise
both models are the same in every way.
The FT-101Z was delivered in all the versions, from MK0 to MK3.
The digital counter module was an option and update is easy if you can find
one because all wiring is available in every transceiver. Just plug it in.
For all models with a serial number under 159999 you need the early type
counter module with TTL IC’s, above 16000 the newer counter with LSI chip.
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The various models and the used boards
FT-101ZD MK0
FT-101ZD MK1
FT-101ZD MK2
FT-101ZD MK3
01 – 07xxxx
08 – 16xxxx
17 – 23xxxx
24 – upxxxx
RF board
Premix LO
Rect A
Rect B
Trimmer A
Trimmer B
Trimmer C
Lever switch
AM (**)
FM (**)
PB1978 (*)
PB1979 (*)
PB1980 (*)
only production numbers starting 16xxxx had the PB2086A counter
optional, the AM board, or the FM board can be installed (MK3 only).
The used boards in detail:
RF boards
PB1960A and PB2154A
Contains the RF pre-amplifier, the receiver and transmitter mixer and a buffer stage,
The mixer output of 8.9875Mhz goes to the IF board. The in and output tuning of the
RF amplifier is done by permeability-tuned circuits, resulting in high sensitivity and
excellent rejection of unwanted out-of-band signals.
PB-9060A RF board component side
PB-9060A RF board solder side
The difference between the two boards is the mixer. The PB1960A uses a balanced
mixer with 2 Fet’s, the later PB2154A board uses a diode ring mixer, for a better big
signal behavior.
PB-2154A RF board component side
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IF board
The IF board is the heart of the transceiver, and is the same in every type of FT-101ZD.
The signal is first passed trough a monolithic filter with a bandwith of 10 khz, to have a wide band point for noise
blanking. The signal pass then the noise blanker gate and is fed trough the SSB filter or the optional CW filter to the IF
first mixer. Here the incoming signal is heterodyned with a 19.7475 Mhz local signal. This local signal is delivered from a
XCO and the resulting mixing frequency is 10.76 Mhz. This 10.76 Mhz signal is fed trough a second SSB filter, and mixes
with the same 19.7475 Mhz local signal back to the original IF frequency of 8.9875 Mhz. The 19.7475 Mhz XCO is tuned
with a varicap over a close range, and the result is that the passband of the first and second filter shifts along each other,
so in effect making the passband smaller or broader, depending of the frequency of the XCO. It is a very useful item, you
can make the band pass as low as 300 hz, and as high as the original passband of the first filter. (SSB 2.4 khz, CW 300 or
600 hz). The skirt of the filters add, so the filter passband improves too.
The output from the second IF mixer is fed to a 2-stage IF amplifier, and is delivered to the AF unit.
On the board are also a AGC amplifier and S-meter amplifier, the SSB tx IF filtering and the speech processor with filter.
The board has the SSB filter installed, and there is room for installing a 300 or 600 hz CW filter (XF-8.9HC).
NB-Fix unit
This board is also used in every FT-101ZD, and contains the noise blanker
circuitry and a x-tal oscillator for 2 fixed frequencies. The fixed
frequencies are sideband dependent, so the operating frequency is on
LSB 3 khz higher than on USB at a given x-tal frequency.
The necessary x-tals have to be in the VFO (5 – 5.5 Mhz) range.
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AF Unit
The AF unit board contains the SSB/CW diode ring demodulator and the carrier oscillator:
USB, CW rx 8989 khz
8986 khz
CW tx
8988.3 Khz
The audio signal is amplified and delivered to the internal or external speaker.
On the AF board is also the marker generator, who provides a 25 khz marker signal for alignment and testing purposes.
The tx microphone amplifier with sideband generator, and a 800 hz sidetone generator for CW are also a part of the AF
unit. The AF unit board is used in every model.
VFO Unit
The VFO uses a modified Collpitts type oscillator to generate a 5 –5.5 Mhz VFO signal,
producing a 500 khz tuning range. The VFO tuning is extremely liniair over the entire
range, no small feat with the use of a “normal” tuning condenser. Stability is very
good, and tuning is very exact with the smooth precision gear. The VFO is one of the
reasons for the good overall stability of the transceiver.
The VFO frequency can varied by a small amount, providing a offset of +/- 5 Khz, by a
varicap diode and a controlling voltage. (Clarifier), very useful when you are in a net,
when all members are not exactly at the same frequency.
Can be used in TX and Rx mode, or both.
This VFO unit is used in all the FT-101ZD and FT-901DM series transceivers.
Premix Local Unit (Mk0 and Mk1)
This plug-in board has 10 crystal oscillators, who are selected by diode switches, they
generate the premix local signal for each of the amateur bands + WWV. It is possible
to add another band on the board, by adding the neccessary components and rewire
the bandswitch.
The local signal is delivered to the Premix Unit.
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This is the newer plug-in board, used in FT-101ZD
MK2 and MK3, that has all amateur bands including
the WARC bands 30m, 17m, and 12m. This board
has no WWV or a optional AUX band.
Premix Unit
PB1962, PB2152
The premix unit mixes the signal from the Premix
Local Unit with the VFO or crystal controlled signal in
a double balanced mixer. The premix signal is passed
trough a bandpass filter and delivered to the RF Unit.
The older board PB1962 has 7 filters, the newer
WARC board PB2152 has 9 filters, for coverage of all
amateur bands, including the WARC bands in the FT101ZD MK2 and MK3. See the table.
The MSM-9520RS was produced
solely for Yaesu, and was never
on the market. There is a kit
available, with a PIC processor,
wich substitutes all functions.
See the page 19 or the site:
Counter Unit
PB1978, PB1979, PB1980,
Used in production runs 01 to 15 in the 101ZD
This counter is a complete enclosed unit, consisting
of a display board, a counter board and a count/
decode board. The unit uses standard TTL circuits.
The counter has a offset programming to display the
correct frequency of the carrier in a ingenious
manner. The counter is programmable for other
offsets with dipswitches. The counter uses 6 HP red
LED displays, for a frequency readout to 100 hz.
PB2086A-3420, PB2098
Used in production runs 16- to the end in the 101ZD
series This counter uses a custom LSI chip, the OKI
MSM-9520RS, wich has all the possibilities of the
older counter including the frequency offset in one
chip. The rest of the board is used for the transistor
digit and segment drivers. The yellow LED displays in
this counter are multiplexed.
AM Unit
The AM print has a AM detector and audio preamplifier, and at the transmitting side the necessary
circuits for the production of a AM signal.
This board is used in the FT-101ZD MK1, MK2 and
MK3. It is a optional board, so it is not used in all
FM Unit
This optional board is used for receiving and
transmitting in FM mode. The board uses the same
connections as the AM board, which must be
removed (if installed) when installing the FM board.
Only one board can be installed at a time, so you
must make a choice. Installing is rather easy.
This board can be installed in production runs from
24 up, the FT-101ZD MK3
Power Supply
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Rectifier A board.
This board delivers all the high and low voltages used in the transceiver, so be careful,
there are points with 900 Volts dc on this board, and that voltage can do serious
damage to a unsuspecting Ham to say the least.
Unload always the condensors, preferabely with a resistor, before starting to work at
this circuits.
The board is positioned in the underside of the transceiver and delivers the various
low voltages (6, 8, 12 Volt dc) and the 900Vdc for the Power Amplifier.
This board is used in all models of the FT-101ZD.
Rectifier B board
This board delivers the bias voltages of the PA unit, the 150, 160, 200 and 300 Vdc for
the driver and Power amplifier. This board is mounted at the left side of the
On this board is also the CW keyer circuit.
The board is used in all models.
The APF unit is switched in the audio circuit by the APF/Notch switch on the
For APF operation it forms a selective active filter, to narrow the passband of the
receiver for a better reception on a crowded band.
The notch function elimenates selective some audio frequencies, like carriers or other
interfering signals.
The center frequency of the APF/Notch is adjustable from the front.
This unit is used only in the MK3 model.
12BY7A Driver board
The driver board amplifies the SSB/CW signal and feeds it to the PA.
The driver uses a tube (12BY7A) for delivering the neccessary power, and the tube is
also used in the automatic level control circuit (ALC).
Part of the output is available at a connector at the back, for use with transverters or
other purposes. It delivers 3V RMS into 50 ohms.
Tuning is done with the same inductive tuning unit, that is used by the RF board.
The inductive tuning allows a constant output over a greater range.
The heater of the tube is switched by the heater switch on the front. Using this switch
during longer receiving-only periods, the tube will last much longer, and there is less
heating up. Warming up time for the tube is abouth 60 seconds.
If you have lower output from the PA, check this tube first.
The trimmer boards (MK0/1/2)
The inductive tuning unit
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The Driver board position
The Power Amplifier
The Power Amplifier, consists of two 6146B heavy duty transmitting tubes, the input filter and the output filter.
The output filter delivers the RF signal to a suitable antenna. The impedance from the antenna has to be between 50 and
75 ohms unbalanced. A Antenna with a different impedance at the feedpoint can be used, but there must be a matching
device between the transceiver and this feedpoint. The same goes for other antennas with a lower impedance such as
magnetic loops and others.
The 6146B PA tubes are very rugged, and can deliver around 100 -120 Watts output depending on the band of operation,
by a input of 180W in the SSB and CW mode. In AM mode the maximum input power is 45 Watt. This is due the fact that
the SSB signal has just one sideband, which has only 25% of the power factor of a AM signal, so the tubes can deliver in
SSB 4x the power of a AM signal, at the same dissipation.
It is never a good idea to push the PA to the limit, it is much better to run the PA with powers around 150W input in SSB/
CW, the tubes will last much longer, and the difference at the receiving station is minimal. You will be surprised how many
DX stations can be worked with low power. It all depends on an effective antenna, band conditions and operating skill,
and not only big power: you have to double your power output to make a S-point difference at the receiving station!
A good antenna is a better investment than big power: It works 2-ways, you even hear the station coming back to you:).
6146 series tubes:
There are several different types of 6146 tubes, and, now tubes are getting scarce is it good to know what possibilities
there are for replacing the tubes with others. The FT-101ZD uses the 6146B type, which has the biggest dissipation, thus
the biggest output, but has a bad reputation for VHF oscillation and TVI as result. They must be very good neutralized,
otherwise the PA destroys itself. The basic 6146 and 6146A (same tube, with a sturdier heater) is still around in great
numbers an can be used if there are no 6146B’s available. The only drawback is the lower power capacity: the anode
dissipation is 25% lower and they need a new neutralization and a correction of the bias voltage.
Another tube is the 6146W, a military designation, used as a remplace for 6146, 6146A and 6146B in the forces. This
tube has a rugged construction, similar to the 6146B, but the saying goes that the input power on this tube should also
be reduced to ca 75% of the nominal output of the 6146B. 6146 and 6146A may be mixed, but never mix a 6146(A) with
a 6146B, because you are in for very strange effects, and some fireworks.
There are other tube designations, they are put together in a small table at one of the next pages.
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Cooler Fan
The optional cooling fan can easely installed on the FT-101ZD. If you use another fan
than the original Yaesu fan, see to it that the voltage on the connector is 100 Volt ac.
DC-DC Converter
The DC-Dc converter allows the mobile use of the FT-101ZD, on a 13.8 Vdc source.
The unit is installed on the back of the transceiver and uses the internal transformer to
obtain the proper voltages. The power connection is made by a special DC cord,
delivered together with the DC-DC converter. On the later Mk3 version this connector
is not fitted and is part of the optional DC-DC converter packet.
FV-101Z external VFO
This is a compact remote VFO for the FT-101ZD. The VFO has a analog frequency
display. If you use it with a FT-101ZD, the frequency is displayed on the digital display
from the FT-101ZD. The VFO has a precision tuning mechanism with a silky-smooth
operation. Clarifier for transmit,receive or transceive frequency is included. The VFO
shift range is +/- 8khz. Up to 6 crystal-controlled channels may be installed. The
necessary crystals have to be in the 5 - 5.5 Mhz range.
FV-101DM external VFO
This VFO has twelve memories, up/down scanning, keyboard frequency entry and
receiver offset tuning in 10hz steps. This provides smooth and precise tuning for SSB
and CW. Either the keyboard, main tuning knob or up/down scanning buttons can be
used for quick QSY to you preferred operation frequency. Up to four of you most used
memory channels can be protected from overwriting, when you store frequencies.
The two-loop PLL circuit is designed to produce a crisp, clean output signal for a
spurious-free receiver and transmitter.
This VFO can only be used with the FT-101ZD MK3, serial numbers above 240001
YR-901 CW-RTTY reader
The YR-901 is a microprocessor controlled code processor that decodes Morse and
Teletype signals and displays plain text on a standard monitor, as well translating
ASCII and teletype machine output into morse or teletype signals.
It displays a 5x7 dot matrix caracters in english or Japanese Kana code in Japanese
characters. Instead of a noisy teletype machine it can also use the YK-901 ASCII
keyboard for Morse and RTTY. For FSK, all of the common shifts may be used. 45.5
and 50 baud are standard, while a easy modification for 57 and 75 baud is possible.
The CW input frequency may be varied between 600 hz and 1 Khz.
FL2100Z Linear Amplifier
The FL-2100 is special designed for the FT-101ZD
transceiver. It uses two rugged 572B/T160 transmitting
triodes in a class AB2 grounded grid configuration.
Power input is 1200 watts PEP on SSB and 1KW on
CW, on all bands, including the WARC bands 10, 18
and 24 Mhz. The linear has 2 fans for cooling the final
tubes, and special protection circuits for the output
tubes and the tank circuit.
During standby is the antenne switched to the
transceiver and the built-in SWR meter allows
monitoring of the feedline during either amplifier or
exciter-only operation.
The heavy-duty powersupply requires no warm-up time
and has excellent regulation.
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FT-901DM accessoires on the FT-101ZD
The FT-101ZD can use accessories of the FT-901DM, but there are some
restrictions at their use.
FV-901DM external VFO
This is a external VFO that provide a synthesized control system for your FT-101ZD. It
has a 3-speed scanner, which will take you instantly everywhere in the band, and the
auto-scan feature sweeps the band until it finds a signal. The synthesizer has a
steprate of 100 hz and is coupled to a 40-memory bank for storing the frequency. Fine
tune is done with the TX/RX clarifier.
Because there is no frequency display on the FV-901DM, use of this VFO in
combination with the analog FT-101Z is not possible, as the operating frequency
cannot determined.
FTV-901R transverter
The FTV-901R is a 3-band VHF/UHF transverter, all in one compact case. The basic
FTV-901R comes equipped for 144 – 148 Mhz. 6 meter and 70 centimeter modules
may be added.
The satellite 1-3 bands provide operation on OSCAR modes A/B/J on full duplex, when
a external receiver is used. Repeater split is provided on 6 and 2 meters.
YO-901 Multicscope
The YO-901 Multiscope provides superb monitoring capability, with a instant interface
to the FT-101ZD and can be used to monitor the output signal with trapezoidal and
two-tone tests, general oscilloscope measurements are also possible. A panoramic
adapter is a available option for a quick band activity examination. IF rx and tx
monitoring is not possible with the FT-101ZD combination.
SP-901P speaker/hybrid phone patch
The SP-901P features a shapedresponse loudspeaker and a hybrid
phone patch, allowing efficient
operation during patches. Styling and
size match the FT-101ZD and FT-901DM
FC-901or FC-902 Antenne coupler
The FC-901 antenna coupler presents a
50 ohm load to your FT-101ZD
transceiver, all across the band. 3 coaxfed and one random-wire antenna may
be accomodated.
The SWR and Power metering allow
quick determination of proper matching
The FC-901 has the Classic Ham-Bands,
The FC-902 has the Warc Bands
included. Max power is 400 Watts.
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A Internet buy
The PA with 6146A and 6146B tube
The “skilfully repaired” PA
The creative relay solution and choke
The PA now, after reconstruction
Recently I bougt a FT-101Z on the Internet for a reasonable price, intended
more or less as spare for my FT-101ZD, that I own for almost 36 years now,
obtained new in 1979, one of the first production runs. The normal asking
price overhere is around 350 Euro’s, depending on condition. The price at 175
Euro (around $200) was good. The distance to the owner was under 100 Km,
making collecting possible. That way I could see what I got, (it is not the first
time that the pictures used by the auction have nothing to do with the actual
set). Well, the set was also a early version from 1979, so in view of spares for
my own transceiver it was ok. It looked nice enough, some scratches on the
top and sides, but a nice front. After removing the cover, I saw that the cover
of the PA was missing and that the neutralizing condenser was not connected.
The receiver worked ok, I could test that with the griddipper that I always take
with me for this purpose. The Ham was using it for the reception of weather
cards at the time, but had now a transceiver with a general coverage receiver,
for a better coverage. The FT-101Z had of course a analog display, and was
with the optional CW filter. The overall sight of the interior was very nice, and
at first sight I saw no modifications. The original crystals were there for all
amateurbands, the first thing to look for, because many sets are converted to
11 metres and have had a life of hard labour. Only the PA was a mess, it had
been repaired, but in a very crummy way, so I had to restore it back to the
original form. Some wires were half molten and the original wiring was changed.
I could not test the set on the air or at a dummy, because the seller had only a
piece of wire as antenne. The tubes were glowing, so I took the set at home.
Altough it was bought for spares, I could not resist the challenge to make it
working again.
Pulling it apart for a box of maybe never used parts was not in the book.
Besides: you can better have it in one piece, that takes less room then putting
the innards in boxes is my experience. And.. You find the part when you need
it, instead of rummaging in several junk boxes. Then, the set looked very nice
after some cleaning and inspecting. I could always use it as receiver when the
PArestauration failed.
There were no further surprises, only a rewired mike connector, and some
scratchy switches and potmeters. The components, including power supply
condensers and solder joints were OK. However, when I pulled the PA tubes, I
saw to my surprise that they had put in a 6146A along a 6146B tube, one of the
most serious mistakes you can make with this tubes. You have to have 2x
6146(A), or 2x 6146B, and preferabely a matched pair for optimal use. The
input relay was changed in a very crude way, glued to the chassis with a blob
of silicone and the output lowpass filter was removed. Here had someone very
hard worked with a Golden screwdriver..
I have all wiring redone with 0.8mm silvered wire, isolated with the original oil
tubing, repaired the coil connections, rewired the neutalizing parts and the
output power meter. A new coil for the output lowpass filter was made from
1.2mm silvered wire and I put in a new antenna relay with 16A silver contacts.
I think the PA looks a lot better now.
I have used a couple of 6146A tubes in this set, because they were at hand,
and to test the possibility for using that kind of tubes in this PA. They work fine.
The power output is not important for me, 100 Watts does everything I need,
and the output tubes will last forever. In my first FT-101ZD I have still the
original General Electric 6146B final tubes, and they look and work as new.
After all was said and done, I ended thus with 2 working transceivers and still
no spares. :)
Now, in 2016, I can say that there is no need to keep spares, this transceivers
will outlive us easely when carefully used and maybe a little TLC (Tender Loving
The rebuilt PA with 6146A tubes
This manual was downloaded from Fox Tango International
Modifications to the FT-101ZD RF board:
RF Board PB 1960A
This board is used in the first series (0-15xxx)and has a RF amplifier, a dual Fet buffer/amplifier and a balanced Fet
mixer. Altough this board works good and is sensitive as it is, it had for me a big disadvantage:
I have in my neighbourhood a very strong “telex?” type station that is operating exact on 8987 khz, right in the middle of
the IF of the FT-101ZD and FT-901/902. This signal is so strong that it goes clean trough the mixer, so I had a constant,
annoying signal, anywhere I tuned when this station was active. I have already tried to null the signal out with the IF
traps in the receiver front-end, it worked to a degree, but now and then this was signal still strong enough to interfere.
In the last versions of the 101ZD and 901/902
Yeasu uses a different board (PB-2154) with a
double balanced ringmixer, and I tought that it
could be the solution for me, because a DBM has a
maximal isolation between in and output that can
be as much as 60db. Maybe good enough for
getting rid of this very cumbersome 8987khz signal.
Before modification
After a study of the differences of the boards, I
decided to give it a try to wire the 1960 board as
the 2154, using a commercial DBM module.
I got a PB2154 board for a test, and this test
showed that the interfering signal now was so low,
it did not bother me anymore. I could have leaved
it at that, but decided to change a existing 1960A
board with a DBM, as a test and for the benefit of
other users with the same problem. First I modified
the board of my FT-901D, it uses a PB-1702B
board, which is almost the same as the 1960A
board. It had the same problems with IF signals
getting trough the mixer.
As DBM I used a standard CM-1 Double
Balanced Mixer from the junkbox, but a SBL1 or HPF-505 should work also.
The only problem was the conversion loss of
the mixer, and too low signal level output to
the filter. There had to be some
amplification after the mixer, as on the 2154
board. I decided to use a J310 as a
impedance converter and amplifier, as on
the 2154 board. First I removed all
unneccessary components on the board:
T-101, R111, R112, R114, R-115, C111,
C113, C126, Q103 and Q104.
Be careful, the print traces are easely lifted.
Reconnect R116 from the midtap of T102 to
the left pin (bottomside) of T102 and
connect C112 direct from the same pin to
ground at the foil side of the board.
Place J-310 at the right side, drain to the
middle connection of T102, gate to ground,
source to the previous gate point for
connection to the mixer.
Place the mixer as shown in the pictures
with a piece of dual sided tape, upside
down and wire to the existing print traces:
After modification
This manual was downloaded from Fox Tango International
1 and 2 are connected to the 2 holes of the removed T101, pins 3 + 4
go to C114 (VCO)
Pins 5 + 6 are grounded ( do not ground the case, it is connected to pin
2, and carries some DC).
Pin 8 goes to the drain of the J-310, and a resistor of 22 ohm is
connected between pin 7 and ground.
The connections of a DBM is rather standard, the input is at pin 1 and 2,
(here it replaces the input coil of T101, which is removed from the
board, along with the mixer components).
The output is normally on pin 3+4, but I used them for injection of the
VCO signal. That way I could use the low impedance output pins 8+7
for connection to the J310 in grounded gate. Pins 5+6 are grounded.
The amplification can be adjusted by the Drain resistor of the output J310, it should be adjusted to a drain current of maximal 20mA. I have
used a 22 ohm resistor.
I first tested several other configurations with the 2SK19 as buffer, but
they lacked gain. With the J-310 the signal output level is a somewhat
higher than the 2154 board, adjustment is possible with the choice of
the drain resistor (18-100 ohm, not lower).
The results:
What is immediately apparent is that the noise level is
lower than of the unchanged print, lower than the
atmospheric noise. A test signal of 0.05uV/50 ohm from
my HP606 signal generator is easely heard, a signal of
0.5uV is good for a comfortable QSO, if the QRM is low.
I have the luck to live in rather noise-free surroundings,
and even on 40 sometimes the noise level is so low that I
can hear all stations in a roundtable, with a simple dipole.
I measured a sensitivity 0.1uV/50 ohm with both the
1702 and 2154 boards I swapped/tested.
The received signals with the changed board has better
audio and there is less “splatter” from other stations, but
I think the ringmixer modification on the AF board is
responsible for that (see the other mods.)
My greatest satisfaction of this modification is that
I now got rid of this “telex” station on 8987khz, I
have to peak the preselector now at the IF
frequency to find a very faint signal.
Under normal operating conditions that signal is
Questions: Drop me a E-mail or put a posting to the FoxTango
unaudible, even when it was S9 before.
This modification is easely reversable. Save the
original components if you feel the need for that.
Success, 73, Wim PA0PGA
FT-901DM RF board Mod.
Modification of the PB1702B RF Board from the FT-901D goes
more or less along the same lines.
Here a picture of the modified PB-1702 board.
On this I used a HPF-500 DBM from my junkbox, but every other
standard DBM will do. Works like a charm.
All in all, a modification that takes only a hour or so to do.
Recommended for European stations that have the same
problems as I with this on the IF operating station.
Transceivers that are using a PB-2154 board, have no problem, so
there is no modification necessary.
This manual was downloaded from Fox Tango International
Other modifications to the FT-101ZD
FT-101ZD AF Unit PB1964A
Carrier adjustments: The most complaints for bad audio
quality are coming from unadjusted carrier frequencies in
your transceiver; after some 35 years they have to be
adjusted for optimal audio in receive and transmit.
To calibrate the carrier frequencies: Connect a counter to
the middle of pot VR-501
Adjust in receive mode:
USB: 8989.000 khz (trimmer C503)
LSB: 8986.000 khz (trimmer C504)
Adjust in transmit mode ( PA heater switch OFF)
CW: 8988.295 khz (trimmer C505)
Repeat several times, until you get the exact values.
Output to the mixer:
USB/LSB: tx/rx about 2Vpp at the middle of VR-501
(measured with a scope)
CW: tx ca. 3Vpp at the middle of VR-501
Modification of the diode ring mixer:
Yaesu used here 4x 1S1007 silicon diodes, in a ring-mixer
configuration. They are not bad but the performance can
easely improved, by using Schottky Barrier diodes such
as the HP 5082-2800 or BAV types.
If you have the possibility, select them for equal forward
current from a batch at the suppliers place, or order a
special quad.
Selecting is an easy affair:
Use your multimeter in the diode range and connect to
the diodes with a resistor of 4.7 K-ohm in series (value is
not important). You now measure the forward current.
Select 4 diodes that have the same value on the meter or
as close as possible. In a normal batch is it rather easy to
find 4 diodes with the same value.
When you use one of this new and cheap LCD component
testers from China, it is even easier to match a quad.
Now, remove diodes D502 to D505 from the board and
replace them with the schottky barrier diodes in the same
configuration, the ring end is the cathode.
After replacing, the bridge has to be aligned for
maximal carrier suppression with VR-501 and TC502.
Alignment is done in tx mode ( Heater switch OFF)
because it is most important to have a good carrier
null for a clean output SSB signal.
Connect a oscilloscope to pin 2 of the print (SSB out),
and null the oscillator signal with VR-501 and TC502, repeat several times in USB and LSB mode for
the lowest output. ( I had a value of less than 5mV.)
When you have selected equal diodes, both the pot
and potmeter are near the middle of their range.
by Wim Penders PA0PGA
I measured the old 1S-1007 diodes, they were close but
not as equal to each other as the schottkys.
Tests on 40 and 20 meters showed a audible lower
noise level and much improved received signals,
because the schottky diodes handle bigger signals
more better.
There is also less “splatter” from other stations
(exept the ones with their overdriven kilowatts
and compressors), so it seems that not all splatter
is generated on the band but also for a part in the
receivers by overloading the first mixer.
Listening on 40 and 20 shows that the average
signal levels not much differ from before the mod,
but the signals are much cleaner and the noise
level is lower, ideal for DXing.
The noise level on the higher bands is lower than
the atmospheric noise from the antenna, I can
even hear a difference on 80m.
Signal comparations have been done with another
trusty FT-101ZD, on the same antenna and time.
The tx has now a much cleaner signal on the
oscilloscope, with no flat topping, even when the mike
level is fully up.
I use a standard Yaesu low-impedance handmike and
receive good modulation reports.
All in all is it a easy job, that results in a real
improvement on both rx and tx side. I have done this
mod too on my FT-901DM, with equally good results.
RF in the audio stage:
Some sets have problems with a distorted audio due the
RF that reaches the microphone stage. The real fault
here is a bad ground connection or a ground loop.
A 10nF condenser between every microphone pin and a
common earth is in most cases enough to eleminate this,
but proper grounding on one point, preferably at the
antenne tuner, if used, is better. Try always to keep the
RF out of your shack, It will give some very weird
problems with your equipment.
To be continued.....
73, Wim PA0PGA
This manual was downloaded from Fox Tango International
Cold Neutralizing The FT-101ZD
by Peter Roberts, G4DJB
The standard neutralisation method used by FT-101 owners
suffers from a couple of major drawbacks – the finals are
producing RF (i.e. are ‘hot’) and the method requires a lot
of ‘tweak and try’.
This results in a lengthy process during which the finals
may get very hot, or may even be destroyed if they should
go into oscillation and the operator is not quick with the
OFF switch.
The method described here is not new, but may be new to
some FT-101 owners.
It allows the neutralisation of the finals whilst they are
‘cold’ (not actively producing RF). The operator may
therefore take their time and there is no chance of the
finals being damaged.
As pointed out, this method is not new.
Please refer to an excellent website by Tom, W8JI
in which he discusses the need for neutralisation and ways
it may be achieved.
The cold neutralisation method works as it takes advantage
of the fact that inter-electrode capacitances are present
whether the device is ‘hot’ or ‘cold’.
In a ‘cold’ device, the grid-plate capacitance acts as a path
through the circuit, and so a proportion of the drive signal
will appear at the output. The purpose of neutralisation is
to couple an amount of signal back to the driver equal in
amplitude and in antiphase to the finals’ grid-plate coupled
So, the net effect should be to cancel out any signal
feedthrough. In practice, cancellation will not be complete,
but it is possible to adjust for minimum feedthrough.
In the FT-101ZD, ‘cold neutralisation’ is achieved as follows:
1. Make sure that the transceiver has the PA compartment
covers fitted (top and bottom).
2. Remove the “Accessory” plug from the rear panel.
This opens the heaters in the finals, but keeps the heater
active in the driver.
3. Connect the transceiver RF output (ANT connector) to
a detector of some sort. (I use an oscilloscope with a BNC
“T” piece adaptor, the third arm of which has a 50-ohm
termination directly mounted to it. A standard
communications receiver will probably be too sensitive, may
suffer damage, and may not give accurate results)
4. Switch on the transceiver, and switch on the Heaters.
Make sure that the finals are not lit, but that the driver is!
5. Set frequency to 29.0 MHz and set the mode switch to
6. Set the carrier level control to about 3 and set the MOX/
PTT/VOX switch to MOX.
7. Adjust the Preselector, Plate and Load controls for
MAXIMUM signal on the detector. Adjust the carrier level
as needed to get a suitable level.
8. Adjust the neutralisation capacitor TC01 (using a nonmetallic trimming tool) for MINIMUM signal on the detector.
Re-peak the Plate and Load controls for MAXIMUM and
re-adjust TC01 for MINIMUM.
9. Repeat step 8 as necessary to find the best setting for
10. You will now find that the Preselector can be adjusted
for more signal output.
- DO NOT ADJUST THIS FOR MAXIMUM. If you do, you will find that TC01 needs to be moved again
by some distance and you will enter an infinite loop of
adjusting Preselector and TC01.
These interact, and so proceed as follows.
11. After step 9, adjust Preselector so that the output signal
increases just a small amount.
Re-peak the Plate and Load controls for MAXIMUM and
re-adjust TC01 for MINIMUM.
12. Repeat step 11 until no further adjustment is required
– TC01 MINIMUM occurs at Preselector MAXIMUM.
At this point stop – you are done.
13. Set the MOX/PTT/VOX switch to MOX, the heater switch
to off and the radio power switch to off.
Remove the detector from the ANT connector and re-fit
the Accessory plug.
The choice of ‘detector’ is entirely up to you.
There may be up to 1-Watt RF present during this process,
so you will need to act accordingly.
As stated above, a communications receiver is probably
not a good idea.
I found that a lot of attenuation was required between the
FT-101 ANT connector and the radios’ antenna terminal
and that RF was leaking around the attenuators making
accurate adjustment impossible.
As an alternative to an oscilloscope, a simple detector
(perhaps following a 50-ohm attenuator) using a diode
and multimeter should be adequate.
For making adjustments, an analogue meter is preferable
to a digital one. 73, Peter G4DJB
Dry joints are difficult to find, but are a
common source
of curious troubles in the cable connectors and boardpins.
Here you see several pins with craters around. See picture.
Resoldering is the cure.
This manual was downloaded from Fox Tango International
Counter MSM-9520RS Replacement Module
The new version of replacement module for
MSM9520RS is available. The module is now
offered as a completed and tested module and
there is no need to modify the counter
mother-board: PB-2086A, so the installation
is much simpler and easier. A 20MHz-clock
PIC MPU still guarantees fast-responding
frequency readout, which results in very
comfortable and smooth operation of your
favorite YAESU.
"Pre-DSP/MPU era FT transceivers" from
YAESU often depend on a custom integrated
circuit (IC), MSM9520RS for their frequency
display function. For reason unknown,
MSM9520RSs from early production lots
definitively fail after certain period of
operation. It has been almost 35 years since
these FTs left the YAESU factory, many of
existing FTs have to retire only because of
their frequency display failure.
This replacement module takes advantages
of the flexibilities of MPU (PIC 16F883) to
simulate the exact functionalities of
MSM9520RS and extends the life of FTs, great
masterpieces of analog circuit technology.
Applicable Models
The replacement module can be used for the
following YAESU FT models. (Please note:
Some early FT-101Z, FT-901 use a TTL-based
frequency counter; MSM9520RS is not used.
Check with your display board before
ordering.) For FT-77, please contact me for
FT-101Z (MK1:16xxxx-, MK2, MK3)
FT-901/FT-902 (with PB-2086A board)
Font Option
There are 2 possible character shapes for displaying "7" depending on the use of segment "f" in 7 segments of
the LED. MSM9520RS original display is shown in the right photo, whereas the left photo is the default for the
replacement module. If you like to have the right, MSM9520RS original font shape, please tell me so, I will
ship a special version to you then, otherwise, the left, "smart" shape version will be shipped.
Price: ask for quote: (3460 JPY nov 2015)(Shipping anywhere on the globe included).
USD/EUR payment is possible through PayPal or Western Union.
3 possible payment methods:
1) PayPal ( http://www.paypal.com/ : Credit Card payment is acceptable through PayPal.)
2) Western Union Money Transfer
3) International Postal Money Order
The module is shipped via registered airmail (in padded envelope) with header-pins for installation.
Support: Please contact Teruhiko Hayashi (JA2SVZ) by e-mail: [email protected] to place order and
for technical support.
This manual was downloaded from Fox Tango International
Gear cleaning/lubricating on the FT series.
The following article describes the dismantling and relubrication of Yaesu and Kenwood reduction
drives used on the VFO. By Wim Penders PA0PGA
As an example I used the drive of a FT-901DM.
The eighties Kenwoods used a similar reduction.
The reason for a drifting VFO is not always found in the
changing in electrical parts, but can also be caused by
mechanical problems.
One is the oxidized earth connection of the VFO tuning
condenser, easely to repair by using some Deoxit or similar
contact cleaner.
The other source is the the reduction gear of the VFO.
Some develop a sluggish feeling when tuned, or after setting
to a frequency it creeps away of the set frequency
mechanically, if only a small amount.
The reason for this behaviour is the lubricant in the first
reduction gear, that over the years is hardened to a sticky
mass that has the tendency to pull back on the movement
of the gear.
Then it is time to clean the gear and relubricate with new
To do that you have to dismantle the first reduction gear
and for that you have to take the VFO out of the transceiver,
wich is a relative simple operation in the FT-101ZD and FT901/902. The VFO is a selfcontained unit that can be taken
out trough the front of the transceiver by loosing the 4
screws on the front, removing the counter unit and
disconnecting the VFO plug and light bulbs. In some
transceivers is it necessary to remove the PLL and VCO unit
to get to a earth connection on the VFO.
To disassemble the vernier drive to clean and lubricate, use
a clean workbench and a room with a hard floor where you
can find the small parts when they get a life of their own
(balls of the bearing, springs in the cog wheels a.s.o.).
Work at your leisure, this is not done by rushing things.
Keep all small parts in a small box, and have cleaning tissues
handy. As always: proceed on your own risk, if you are in
doubt, don’t do it, it is a job that needs patience and affinity
for mechanical things.
- Remove the security clip in front of the big knurled bushing
of the ball drive reduction.
- Remove the knurled bushing, take it off the main axis
together with the 3 or 4 pressure rings and the ball bearing
that is inside the bushing.
- Pull now the main axis 2mm out. In some drives this
disengages one of the 2 wheelparts on the reduction gear
inside the big gear housing.
Before mounting the axis again, you have to load the spring
in such a way that there is some tension on the gear spring
before you are able to get the axis on the cogwheel again.
Be careful to keep the small springs in place, otherwise you
have to fumble a lot to get them in again.
- Gently pull the insert from the main axis to remove the
sticky grease. When the insert comes out, there is almost
always a small ball attached to it, make sure that you
don’t loose it, it is a crucial part of the reduction.
Take out the 3 balls of the bearing and clean them too.
- Now remove the old grease from the ball bearing, use a
small brush and kerosene or white spirit, no hard tools!!.
- Clean also the other small parts, and the knurled bushing.
- Turn the gear towards one of the end points.
- Take off the tuning knob by loosing the 2 screws.
- Take off the khz correction knob (3 small screws)
- Take off the frontframe, notice the position of the fiber
- Pull off the khz scala and the ring in front of the 100khz
- Take off the 100khz scala by removing the 2 small screws
- Put both scala’s on a safe place, they are easely scratched.
- Mark the position of the cogwheel and gear with a marker,
for later assembling in the same position.
- Take the cogwheel off after removing the security clip.
- Be careful to keep the 2 small springs in the cogwheel in
This manual was downloaded from Fox Tango International
Fig 1
This manual was downloaded from Fox Tango International
- After cleaning and drying, you
can relubricate the gear with a
good ball-bearing grease. I
used a grease with lithium, got
this stuff from a local bike shop
that sells it in 110gr boxes.
- Fill the bearing with the new
grease, use enough to keep the
ball bearing from running dry,
fill also the hollow axis and
insert before putting it back,
with the small bearing ball first.
The small ball is necessary for
a silk-smooth operation of the
After putting the insert axis and the small ball in push the main axis back on the cog gear. If there was one of the cogwheel
half disengaged, when the insert was pulled, you need to load the springs by pushing the last wheelpart 1 teeth in the good
direction, not more, (when more power is used on the back half of the cogwheel, is it possible to lose the small springs, they
will jump out), Been there.....
Close the ball bearing by putting the gear ring in first with
the hollow side towards the ball bearing. Then put in the 3
or 4 wobbly tension rings, a eventually (not all gears have
it), a normal ring. Now make sure that the whole room
beside the 3 ball bearings is filled with grease, then close
the ball bearing with the knurled bushing.
Wipe off the excess grease and push the security clip on
The rest of the assembly is in reverse order as the
disassembling above.
The 100 khz cogwheel is set with the help of the marker,
that you put on. Is there no marker, you can do it in this
Turn the VFO to one of the endstops, push the cogwheel
over the axis and engage the second wheelpart also with
one teeth pressure.
Mount the cogwheel in such a way that the the 2 screwholes
are in a horizontal direction. Secure it with the second
security clip.
Now turn the assembled gear several times from end to
The exploded view of the gear displayed above is similar
end and make sure that it is running smoothly.
in build as the FT- series VFO gear.
If you feel some “rough” spots, loosen the knurled bushing
Clear to see is the construction of the balldrive.
somewhat, if the bearing slips, increase the tension.
Pos 2, 3, 4, 5 and 6 are different in the FT gear.
A good assembled reduction drive will turn silky-smooth.
Re-assemble then the 100khz scala then the khz scala.
It is possible to make small corrections in the 100khz scala
position by changing the position of the small cogwheel B
on the previous page, by loosing the 2 small screws on
them and turn the scala B until the scala is on the right
position, you can check with a strong signal of a calibrated
signal generator.
Dont forget the separation ring between the two scalas.
Mount the front panel, the khz corrector knob, and the
pressure ring with the plastic ring.
The khz corrector must have a certain pressure, push the
top side in such a way that the top of the plate is flush with
the end of the main axis. Give the rest of the reduction
gear and the bearing of the variable condensor a drop of
silicon oil, and put the VFO back in the transceiver. Enjoy
the real smooth operation of the tuning now.
Good Luck, 73, Wim PAØPGA
This manual was downloaded from Fox Tango International
Kill The Killer Condenser !!!
One of the most common reasons why a Yaesu tube
transceiver is discarded or stripped in parts is a small part
in the PA cage: the notorious Killer Condenser C01,
(FT-101ZD 1000pf, 901DM 100pf).
If you have not already changed this part, check if the
original Yaesu part is still there and change it. It is the
coupling condenser between the 12BY7 anode and the grid
of the PA tubes. The condenser that Yaesu fitted here is a
mica condenser.
This part will fail in time and puts then 300V on the grid of
the 6146B’s, who in turn pull all the current they can get,
destroying the tubes and the power transformer if you are
not nearby, rendering the transceiver useless.
I have seen 6146B’s that got so hot that there was a hole
melted in the envelope, looked if shot by a .22.
This can happen too when the set is in receive mode with
the heaters on, in many cases the unsuspecting Ham was
not in the shack, and by returning there was greeted by a
waft of very expensive smoke.
The Killer Condenser is located on the PA board (PB1715).
For the older FT-101ZD’s you have to remove the PA board,
To get to it, you have to pull the tubes out, loosen the 6
screws and desolder one or two wires.
For the FT-101ZDmk3, this condenser is located on the top
of the board, so you just cut the wires and solder the new
one in.
Replace the condenser with the same value (100pf for the
FT-901DM, 1000pf for the FT-101ZD. Use a 2-4 Kv ceramic
condenser here, there is no need to use mica , mica has a
higher ESR value, and that is part of the problem.
The new condenser can be mounted on the topside of the
board, there is room enough.
Check also the mains fuse for the correct value: 5Amp fast
blow for 110V operation and 3Amps fast blow for 230V.
Yaesu FT Line in station PA0PGA
The FT-101ZD Mk3 story
The FT-101ZD Mk3 is the newest in the FT ZD line and is
one of the last transceivers with a tube type final.
It differs in several ways a bit from the earlier FT-101ZD’s
in that it has all the bells and whistles of the previous series,
but has also several new features such as the possibility to
use the FV-101DM scanning Digital VFO, a choice between
a AM or FM board, audio peak filter and notch, and a squelch
knob for the FM board.
The possibility of using FM was not really new, but in
combination with the FTV-901 transverter, you can work on
50Mhz, 144-148 Mhz and 430-440 Mhz. This transverter
has the possibility to use up to 3 modules. Together with
the FT-901 and the ft-101ZD, you have a complete station
on HF and VHF/UHF.
The FV-101DM is a Digital VFO, a VFO that was special
developed for the FT-101ZD Mk3, it has 12 memory channels
that can be used as the starting point for 12 different
frequencies, in fact you have 12 extra VFO’s, ideal for spot
listening and working splits. It has scanning capability.
It enhances the capability of the FT-101ZD Mk3 in a great
way. To be able to use all the features, there was a second
cable necessary to the transceiver for communication
between the two, the reason it not works on the earlier
Another difference is the omitted connector for the 12V
DC-DC inverter, wich was now a optional unit that contained
not only the Power inverter, but also the special connector
that must be installed in the set. The cabling is already
done so far, you only need to mount the connector.
There are more differences: the trimmerboards have another
arrangement of the trimmers. (see page 26)
New was also the combined width knop, a audio passband
filter tuning knob combined with a notch filter a welcome
addition for fishing small signals out of the crud.
The performance of the Mk3 was now nearly as good as
her big brother, the FT-902DM. Both were soon replaced by
newer designs that were completely solid-state.
En era had ended......
This manual was downloaded from Fox Tango International
FT-101ZD Mark3
(serial 240000 and up) Trimmer positions
C trimmerboard
Start the alignment on
10M, and only by changing
the T3 preselectorcoil.+
B trimmerboard
A trimmerboard
This manual was downloaded from Fox Tango International
Mark 0 and 1
Because our FT-101ZD’s are getting
older they may profit from a realignment. Many Hams are unsure
of the positions of the trimmers,
maybe this pages brings light in the
Something you have to check: the
coupling between the 2 switches.
More than once Hams have searched to
solve a strange fault in the TX behavior
of the FT-101ZD, and found at last this
coupling loose ..............
The trimmer boards (MK0/1/2)
The inductive tuning unit
Many Hams search for the T1, T2 and
T3 transformers when aligning a set,
Here they are.
Mark 2
The trimmerboards of the FT-101ZD from
serial 010001 to 079999, 08001 until serial
169999 are the same as the later series
170000 to 239999, the Mark2.
No new band trimmers for the WARC
bands in the Mk2, they use the same ones
as in the above picture, but were
combined with the next higher band. ie:
20m trimmer aligns 30 + 20m
17m trimmer aligns 17 + 15m
12m trimmer aligns 12 + 10m
Serial numbers above 240001 are used
for the FT-101ZD Mk3, and have dedicated
trimmers for all bands.
Because there was no info that I could
find on the net, I measured them out and
the result is on the previous page.
This manual was downloaded from Fox Tango International
The Driver board position
A FT-101ZD Mk3 rescue story,
by Murray, ZL3MH
This is my blog of my new but old FT101zd MK3 to run the
FTV650b on 6m and a FTV250 of repairs and mod’s.
Today my old but new FT101zd MK3 arrived from the North
Island of ZL. The Cosmetic condition of the front panel
has almost no marks ( most important ). The rap around
covers ( case ) are quite marked and needs repainting.
The radio seems to work ok
but the band switch needs cleaning ( On 40m the switch
needs tweaking to make the radio work ) The same trouble
with the CW-W position mode switch.
The radio is a cut down version , no CW filter and no mobile
power supply. There is no FM or AM board fitted either but
it has a fan unit. There were very few cut down units
imported to ZL land. May be it came from VK.
I have a FT101zd MK2 in a battered state but is now going
after 40 hrs of repairs. I have already swapped the mobile
power unit from the MK2 to the new MK3
I also changed the Plate to Grid capacitor that gave so
much trouble in the FT101 ( .001 at 4kv ). See pictures
The second night of the repairs and modifications. I
swapped the CW narrow crystal across to the MK3 from
the MK2. This is a major job removing the Crystal / Noise
Blanker board and the IF board.
I ran the +800, +300, +160.-100 supplies to the ACC plug
for the FTV650b as per the MK2.
Please be very careful of the Plate Supply as the capacitors
can remain charged for over 24 hours.
After 24 hours ( still 400v ).
----NOTE up to 900v DC no load---I also did a modification by adding two 10uf 35v Tantalum
capacitors to earth on PB-1967 from terminals B and C to
stop regulator Q901 taking off when it gets hot. This is a
common problem that can cause poor voltage regulation
to the VFO that will cause a FM effect on Transmit on SSB
peaks. Q901 can oscillate at 20Kc
The third night I marked the Band Switch where it converts
from metal to fiber and checking the tightness of the
screws. I also cleaned the contacts on the switch so 40m
now works ok. I also cleaned the CW Narrow contacts on
the Mode Switch.
This manual was downloaded from Fox Tango International
from the top. I resoldered the PCboard PB1973 ( Clarifier
unit ) and removed the top of the relay and tried to clean
it with contact cleaner . The relay top said 211A DO12-M
and F SV3. I also cleaned the switches. I do suspect the
relay contact being faulty. All this has taken an hour and
time will tell if the problem comes back again.
The forth night I ran the rig up on 80m, 40m, 20m and
worked a few stations. I noticed the IC idle current was
around 75-90 ma so I adjusted it back to 50 ma. I worked
a few more stations. Then I hooked up the Microwave
Modules Converter 28MHz to 435MHz and worked VK2ZAZ
on FO-29. Then I turned on the FTV650b and called CQ on
50.110 but no replies.
Day five, Something very important. Check the power fuse,
3 amp for 230v and 5 amp for 110v. I am using a 2.5 amp
normal blow fuse and they hold. The wrong fuse of higher
capacity will do lots of damage if there is a fault inside the
rig. Now I will run the rig for a while to see how it goes. I
hooked up the MM converter and worked VK6AKI Ron on
FO-29 . His signal was S9. Perth is over 5,000 km from
Christchurch and minus 5 hrs in time. We had a good 5
minute contact.
Day 6 , I use the Clarifier a lot on FO-29 doppler and
sometimes it does not work then it moves like a capacitor
is charging up. It has only happened twice. I hope its not
in the VFO board PB-1440b and in the Clarifier unit PB1973A. I will clean the two push button switches and the
pot first. Had a good contact on FO-29 worked ZL3DW,
VK2TXT, VK2ZAZ and VK6AKI in Perth. I listened a bit on
80m tonight and tried out the Width Filter to narrow the
SSB signal down and it works great on the noisy band.
Day 7 Tonight I pulled the Clarifier board out. Their are
two screws to pull out, one that can be done from the
bottom and one by removing the plug in board PB1965
Day 8 Today is Sunday. I am running the ZD all day. It was
open on 6m to VK2+3 but I worked nothing but I was
talking to Rod ZL3NW about 25 km away using the FT101zd
MK3 to the FTV650b Transverter. The FT101 only has 650
volts on the transverter but
the FT101zd series has 800 volts on the single 12v 6146
which really makes it go ( about 50w on 6m ) The Clarifier
seems ok. There is a contest on 20m but I did decode a bit
of SSTV and PSK31.
5 days later . The ZD is still going great. The Clarifier it still
working ok and the rigs
Running good.
Overall I am very pleased with want I got as MK3’s are
quite hard to find. The front panel is in good condition and
all FT101s cases mark very easy as the paint is not very
Remember this rig is 25 years old but it will still give a Non
DSP rig a run for its money.
73 Murray ZL3MH
dB conversion table as used by Yaesu for
alignment of their equipment.
0 dBu = 0.5uV/50 ohm
HP 606A
used in manuals
signal generator
(dB table courtesy of Jerry Becker)
This manual was downloaded from Fox Tango International
Hints and Kinks
PAØPGA and others
In this section I will give facts and thoughts, that I have collected from all over the net.
When sources are known, I will mention them, because to hold your FT-101ZD in an excellent condition is only possible
when all real amateurs, share their knowledge and experiences.
That’s still the first rule for a Ham in my opinion.
Of course are all tips free to use, but using them is always at your own risk. If you don’t have the knowledge or technical
skill, then please let the lids of your set closed, it is always better to have a good working transceiver then a perfect heap
of junk. Never try to be smarter than the HF engineers of the design Lab, there is almost always a good reason that
things are done the way it is.
Most modifications are small, and are additions for a specific reason, not a complete rebuild of the set.
So have said that, we start with a collection of tips:
First of all:
Get the proper user and service manuals for the equipment
that you have, and make yourself familiar with the working
of the circuits. The manuals for the FT-101Z and ZD, and
other Yaesu communication equipment are on the
FoxTango site, in PDF format, free to download, (well, a
small donation the club is very much appreciated,
to keep things rolling), so there is no reason to start
without them.
Special recommended is the very extensive Maintenance
Service Manual, with around 200 pages, which is not only
very interesting, but gives all information on boards,
voltages, trouble shooting lists and in general all information
to keep your FT-101ZD in a first class condition.
Switching the fan:
When the rig is mostly used on receive, there is no need to
let the PA cooling fan run continuous.
I switch the fan with the heaters On/Off switch:
Pick up the 12V of the heater circuit at the accessory socket
at the rear of the transceiver and rectify it with a diode
and a suitable elco. Use the DC voltage to switch a small
relay. I used a small 12V reed relay with 1 contact. Use a
suitable series resistor to limit the current. With the
relaycontact you can now switch one 100 Volt connection
to the fan socket.
I made this modification 25 years ago, and it works still as
a charm. There is room enough in the back of the
transceiver to mount the relay and the couple of small
parts you need in a neat manner.
Improving second Double Balanced Mixer:
On the AF board is the double balanced mixer, D02 to D05,
they are 4x 1S4007.
Replace these with 4x Motorola MBD-702 diodes and the
adjust VR01 and TC02 for the best carrier balance. It should
be possible to null the carrier almost completely.
No or low Calibrator signal:
Replace Q10 on Audio board 2SC1815.
Source PA0PGA
First mixer overload
(only FT-101ZD MK2 and MK3, board PB-2154, used
after run 17xxxx,)
RF board: Improve the dynamic range of the first mixer by
modifying the T-Pad attenuator on the input as follows:
Change R8 (120R) to 36R, change R9 and R10 (10R) to
Reset overall gain on IF board using VR02, which is the
source load of Q15.
Improved Fine-tuning:
Shunt the clarifier control with a 4k7 or 5k6 resistor, then
recentre its action by adjusting VR01.
This mod reduces the control’s range to +/- 2,5 Khz.
Tips from Kiwi land
On 10 meters the transmitter takes off on HF or with the
transverter beiing used. The problem is dry joints or earthing
points around the 12BY7. Resolder all connections on and
around the 12BY7 board.
Low sensitivity rx :
If the marker can be received at the normal level then
suspect the aerial fuse. If the marker signal is low as well
then suspect the PA driver 12BY7A - this shares a signal
frequency tuned circuit with the RF stage. Q8 on the IF
board also causes this problem sometimes.
PA tuning incorrect :
If the PA won’t tune correctly on some of the bands then
check for short circuits on the output tank coil and the
nearby wiring.
No rx :
Check the width control is not set at one end (surprisingly
No tx and no bias :
Check accessory plug is in octal socket at back. Check
the PA screen grid voltage - if it is missing check D1002,
D1012, and R1006 on Rect.B unit.
This manual was downloaded from Fox Tango International
No CW tx :
Check Q1003 on Rect.B unit (possibly Q1001 and Q1002
as well). I have had failure of the CW carrier osc xtal on a
couple of occasions.
No tx 28-30mhz only :
Check R8 which is mounted on the band switch assembly
near the driver.
RF feedback on 21/28mhz :
Some units had a four way tag strip near the mic. i/p socket
- the two centre earth connections should be connected
Incorrect frequency display on one band only :
Suspect the local osc xtal for that band.
Poor rx/tx on one band only : Local osc xtal as above.
11m reconversion :
These rigs were sometimes converted for illegal CB use.
This usually involved replacing 28.5-30 MHz with 26.5 to
28 MHz. A few rigs are still around in this state, and will
require re-converting back to 10
metres. This will require the replacement of the local
oscillator crystals, and re-alignment. Realignment should
not be omitted, as the rigs may intermittently fail to operate
correctly if it is. Change required local osc xtals for the
original types and the local osc must be re-aligned to ensure
continued reliable operation.
Hum on rx when volume control at min :
This is usually caused by a hum loop. If there are two
earth braids connected to the v/c then cut one of these.
Hum on tx :
Same as above but on mic gain control.
One segment of display does not light :
LED U/S. Note these are usually in sockets and are easily
swapped for checking.
The Noise Blanker stops working sometimes.
It appears to be a dry joint on plug pins of the Noise Blanker/
Fixed channel board.
The fix is to solder around the connections of the board.
The transmitter stops working:
The band change switch is in two parts. It is joined where
it goes to the 6146B compartiment from a steel shaft to a
fiber shaft. This connection comes loose, and the bands do
not line up properly.
It is a good precaution to mark the shafts with a markerpen
and tighten the screws on the band switch extension. I
heard from a FT-101ZD repairer spending days to track
this one down.
FTV-250 and FTV-650B on the FT-101ZD.
The FT-101ZD is designed for the FTV-901 series of
transverter via the 11-pin accessory socket.
The Plate, screen and bias voltages are not always wired
to the accessory socket. This is needed if you want to run
the FTV-650B 6-meter transverter that is designed for the
earlier FT-101 series.
Especially the MK3 model did not have the above wiring.
Both the FTV-250 and FTV-650B can be used with this mod
on all FT-101ZD’s.
Help notes on the FT101Z/FT101ZD
Collected tips from everywhere, sources unknown.
** there are several versions of the FT-101ZD, and
some of these faults do not apply to all versions. **
Blowing mains input fuse :
Disconnect PA anode clips to see if one of the PA valves is
short circuited. If not, then some of the diodes in the main
bridge rectifier are probably short circuited.
Incorrect segment illumination on one digit :
Digit driver IC U/S.
Intermittent incorrect frequency display :
If on one band only, suspect the local osc xtal on that band
- check alignment of osc before ordering crystal, especially
if fault is on 10m (because it may have beiing used for
illegal CB and not realigned). If on all bands suspect Q04
or Q05 in the counter (later models) - note that Q04 must
be the S version.
Sizzling/arcing from PA :
Check the PA anode choke.
Intermittent rolling frequency/panel lights dim :
Suspect a dry joint on the LT smoothing cap. Also suspect
the cap itself.
Low power output on some bands :
Check the PA anode choke and also the coupling capacitor
from the PA to the output tank circuitry.
Fault blows main fuse every 0.5 to up to 6 hours and is
not the 6146’s flashing over.
There are vertical type caps in PB-1968 and the internal
fluid runs down and arc across the narrow gap in the caps
(300 Volt screen supply, a common problem in TV sets).
Replace caps C1001, C1002, C1003 and C1004, they are all
10uF/450 Volts.
PA unstable on higher frequency bands :
If the neutralisation is OK, then check if the 12BY7A driver
is glowing blue on transmit - replace if it is.
Intermittent blowing of mains input fuse :
If the fuse blows every now and again, then suspect that
one of the PA valves is flashing over once in a while.
Fluctuations in power output :
Check the PA valves. Check the PA anode choke.
No receive:
Check relay 1 on the audio board,
clean the contact or replace relay.
Source PA0PGA
This manual was downloaded from Fox Tango International
by John, N0BUP
Helping the Helper
This is a Short Guide to Asking for Help in Finding and
Repairing Radio Faults Over the Internet
“I have an old Yaesu 101 that is not working on15 meters.
What’s wrong with it and how canI fix it?” or “I have a bad
15 meter crystal and I need a replacement, but I’m not
certain that this is the problem. How do I tell?”
like these often go unanswered or generate just a few “Have
you checked for . . . ?” kinds of answers on the Yahoosponsored Fox TangoGroup at
and probably on many other radio user groups as well.
Poor responses are sometimes because there aren’t a lot
of readers familiar with that radio, or that particular kind
of fault, but more often there are plenty of readers that
know a lot about how to find and fix the faults asked about,
it is just that they haven’t been given enough information
to make more than a general guess as to what could be
A radio can develop any particular fault for dozens of
reasons. Some are more likely than others, but sometimes
radios can fail for very odd reasons. Moreover, some of
those reasons have literally nothing to do with the radio
itself but are with the antenna, the external power supply
or with things like connecting cables, or add-on units like
power meters and amplifiers or are caused by simple
operator error.
If you want help, take the time to help your helper as
much as you can. It’s a good investment of your time and
of his or hers.
Here is a guide to help you do just that:
1) Start with a good description of the problem and the
equipment being used.
“I have a Yaesu FT-101E that suddenly started putting out
only 10 watts on 15 meters, but it will sometimes put out
full power for a few seconds.” is much more helpful than
“Why does my radio have low power out?”. Sometimes
serial numbers help with earlier models and sometimes
they don’t, but always say what model you are working
with. Don’t let your helper guess whether the fault is also
found on LSB, CW and AM. Tell him up front.
2) Tell the reader what else is not working properly on the
set or what you are not sure is working even if you don’t
think it is important.
“On 15M the calibrator signal seems to be about 10dB lower
than the other bands,” or, “On-air reports tell me my audio
is distorted a little as well,” “My idle current keeps slowly
going up,” or “I think I hear a faint buzzing
sound coming from the radio on 15M,” or “I’m pretty sure
I smelled something burning when it happened,” or “C17
seems to be leaking a little oil,” or “My final tubes have
different brand names on them,” can be very useful clues
when finding faults. If you are getting any funny meter
readings at all, don’t leave your helper guessing about
them—let him know.
It can help to know how you know something isn’t working.
If you are not putting out power on the lower HF bands,
but you’re only using a CB wattmeter, it may well be that
the meter is simply not designed to work at those
3) Tell the reader what you are sure IS working properly
on the radio.
“Ten meters puts out 80 watts and I get at least 100 watts
out on the other bands,” and “The receiver seems to be
working normally on all the bands, but I’m not sure about
10 meters since the band hasn’t been open,” and “I’m
getting full power out on CW and AM and on LSB on a
dummy load, it’s just 15M USB on the air or on the dummy
load that it is weak,” and “My signal reports on the other
bands don’t indicate any audio distortion,” can all help
narrow down the possible fault quite a bit.
4) Tell your helper about the history of the radio
and the history of the fault.
Information such as “I just bought this radio from a CB’er
at a flea market,” or “I’ve had this radio and used it for 15
years now and I just replaced the finals a couple of months
ago,” or “It was my father’s radio and it has been in storage
for the last 15 years,” or “I bought this on Ebay last week
and it looks like there have been a lot of modifications
done to it,” or “It was doing the same thing last year, but it
stopped by itself,” or “It was working fine till I loaned it to
the radio club for that Field Day on the beach,” can often
point to things to be checked first.
5) Tell your reader what you’ve already done to
fix the radio.
“I haven’t done anything yet, I’m looking for where I should
start first,” or “I’ve swapped out the driver tube for one I
know is good,” or “I’ve tested the USB carrier oscillator
and it doesn’t seem to be working,” or “I’ve swapped out
the 15 meter crystal from another radio that a friend has,”
or “I’ve swapped out every plug-in board with one from
another working radio,” or “I’ve cleaned every switch
contact, relay and front-panel control on the rig,” lets your
helper know a lot about what can be eliminated as probable
Since most faults on vintage radios are mechanical, not
electronic, there is a lot to be said for not even asking for
help on a 20 or 30-year old rig until you have cleaned
every internal switch contact, every relay and panel control
that you can, and you have also jiggled, wiggled, and
repeatedly worked every knob and switch there is on the
front and rear panels to see if the problem goes away—
even a little . DeOxit is the preferred contact cleaner in
the US and Canada, but any other ‘tuner cleaner’ designed
This manual was downloaded from Fox Tango International
for electronic gear should work as well. Rough paper is
the preferred cleaning tool for relay points. Don’t use spray
oils like WD-40 to clean electronic equipment.
Sounds like a lot of work? Well, the good news is that
these faults are also the easiest things to fix.
If you haven’t opened up your radio yet, maybe now is the
time to do that:
Especially with older radios, you should take the time
needed to thoroughly examine your radio before you post
a request for help. Some faults can be quickly found by
just looking at a radio. It’s really worthwhile to take 15 or
20 minutes and just look carefully at your rig under a very
bright light to see the obvious. You can often find burned
resistors, filter caps that are leaking oil (or have even
exploded), diodes that have disintegrated, bent variable
capacitor plates, signs of high-voltage arcing, PC boards
that are burned from overheated components, circuit board
cracks, un-expected substitutions of 11 meter crystals, and
tubes that are glowing with wondrous and unusual colors.
Tell the helper, too, if you don’t have basic equipment like a
dummy load, a volt-ohm meter or a standing-wave ratio
meter. If you have another receiver, it can help a lot when
testing transmitted signals, antennas and connecting cables.
Your helper also needs to know what local support you
have. Two day’s overland ride to the nearest electronics
store in the Australian outback? Or just down the street?
Member of a local radio club? Any experienced friends to
help out or who have test equipment that you don’t have
or can help you with on-the-air tests? A friend with an
identical radio can quickly help you eliminate possible
7) Communications are important.
Spelling doesn’t usually matter, but just about everything
else does. Start with the subject heading. Get rid of the
old heading if it’s not relevant. A subject heading that says
“Receive Problem on FTdx570” instead of “Helppp!!!” will
do a lot toward getting you to the right helper on the first
Poking and prodding can also reveal faults that can take
hours to locate with test equipment. Wiggling a connector
or a panel control, pulling tube and replacing it will
sometimes ‘fix’ a broken radio. While you are at it, wiggle
the patch chords and antenna connectors connected to
your radio. Touching circuits can be dangerous but it can
also identify faults you might not otherwise be able to find—
like a hot resistor. Even banging on the side of the rig with
your fist can do wonders for finding intermittent faults.
Most potential helpers will try to read a sentence two or
three times and then move onto better things if they don’t
understand it. It’s astonishing the number of posts that
have sentences that don’t form a complete thought, or
whose beginning and end have to be guessed at, or are
missing needed periods or capital letters or spaces between
words, or are simply incomprehensible any way you try to
read them. Writing like that creates the impression that
you really don’t care whether or not you are understood.
You might be amazed at what can fall out of a radio if you
simply turn it upside down. Staples, paperclips, pennies,
loose screws, nuts, small bolts and lots of dust can find
their way inside an old radio.
Use your nose and ears, too. Sometimes, you can hear
arcing that you cannot see, and you can smell a component
that is overheating long before you see the damage.
If English is your second language (or not your language at
all), try anyway! No one will be offended if you follow your
best-shot-at-it English paragraph with one saying the same
thing in Spanish, German or Italian. It’s amazing what you
can figure out using the new on-line translators like Babelfish
and radio operators often like the challenge of de-coding
communications. Keep your sentence structure simple and
your helper will be able to figure it out half the time—even
if you do speak Hungarian.
Often answers to common repair and fault questions have
been answered many times before. If your questions is
specific enough, you can take advantage of Yahoo’s archive
features and enter something like “neutralizing”into the
‘Search’ feature option. Often you can find your answer,
or at least someone who has some experience with the
problem. You can also send an e-mail directly to the person
that really knows the subject.
6) Tell your helpers just enough about yourself, your level
of knowledge and your equipment setup to let them provide
appropriate advice.
The advice given to a teenager who doesn’t yet own a
soldering iron will often be very different to that given to
an old-timer who has a shack with a 20-year collection of
test equipment. If you don’t have the radio’s instruction
manual, let your helper know. If you are fortunate enough
to maintenance service manual, let him know that as well.
If you just got the radio and you’re not sure how to operate
it because you don’t have a manual or it’s too complicated,
please say so.
Always give feedback on advice already given to you. Don’t
let your advisor guess whether or not something they
recommended was done.
If you didn’t have the dummy load you needed or if you’re
just afraid to reach into the final’s cage to pull a relay
because you don’t know how to discharge the caps, tell
your helper. For extended repairs making a list of “Here’s
what I’ve done so far: . . .” attached to posting is a big
For lengthy or growing problems, try to keep a tracking
letter to attach to your posts. Usually, the past posts (oldest
at the bottom) with the irrelevant stuff stripped off is
plenty—don’t make anyone go back and search the archives
for your last six postings to figure out what your problem
is and what you’ve done to fix it so far. Please!
Never attach your copy of the Yahoo ‘Weekly Digest’ and
hope we’ll somehow find what you’re responding to in there!
Learn to use the simple ‘cut and paste’ features on your
browser and word processor if you haven’t already.
This manual was downloaded from Fox Tango International
Common courtesies are often missing on group posts. You
don’t have ooze Old World charm or compliment your
helper on how handsome he looks on his profile page, but
you should really try to use a minimum of manners when
Don’t be anonymous. At least write your name at the
bottom of your message and your call sign if you have
one. If you are writing for the first time, include a little
information about yourself or fill out your Yahoo profile
page. No one is going to steal your identity if you leave
a photo there or list your age or other hobbies.
Your helpers are doing you a favor and they don’t owe you
the information you’re requesting.
If you talk to them as if they do owe you an answer, you
might find the help you’re getting is very limited. It’s easy
to forget with the anonymity of internet communications,
but simple things like ‘please’ and ‘thank you’ and
addressing people by their names are just as important
when posting to a group as when you’re holding a
conversation in person.
If you don’t agree with what is being said, don’t use it as
an excuse to be impolite and attack the writer—this goes
for helpers as well as ‘helpees.’
Just point out your disagreement and leave the “only an
idiot would suggest that” thoughts out of your posts.
Don’t whine if you’re not happy with the responses you’re
getting . If you don’t get a response right away, it could
be because some readers are only checking the group
postings once a week or they want a little time to study a
circuit diagram or find a reference they have buried away
Request for help aren’t a poll. If one person suggests one
thing and the next person posting suggests something else,
it’s not a necessarily a disagreement. A helper doesn’t
usually want to take the time to repeat good advice already
given by another unless he can add something to what
has already been said. If you don’t get a response in a
couple of weeks, a gentle reminder that you’re still looking
for help is all you should need.
Complaining when someone asks for more information
about your problem—especially if it is information you
should have provided in the first place—is a pretty big turnoff for anyone reading your posts. You’re far better off not
responding at all if you’re tempted to do that. Some
problems are simple to fix, but others really require a lot
of eliminating other possibilities first and that requires
information that you may think is unimportant.
Not giving feedback on information already asked about is
a fast way to turn your helper into a confirmed non-helper.
Unless you are just asking for a reference for a good repair
service, try very hard not to give the impression you’re not
going to lift a finger to help yourself. Asking what you
should do first with a non-working radio while saying it
is full of dust or telling your reader that you haven’t opened
it up to see if all the tubes are there is like inviting your
helper not to reply at all.
Tell your helper when you don’t understand what’s being
said or if you don’t know how to do something. If a helper
suggests cleaning RL-2 before doing anything else and you
don’t know what RL-2 is, how to get it out, or how to take
it apart to clean it, don’t be too embarrassed to ask. That’s
a lot better than letting him think you’ve already cleaned
that relay and it must be something else.
And a final word: Remember, you are the eyes and ears of
the person helping you.
If you don’t tell the helper about something then he or she
won’t know about it.
Helpers and ‘Helpees’ Comments:
Thank you John for this excellent worksheet, let me only
remark one thing, because it can not be repeated often
cleaning cleaning cleaning
that is what I always do first and not all but most of the
problems are gone. Most of these old beauties have not
been used for years and in a clean and dry room, if they
had the luck to be in there and not in a garage or something
else, there is dust.
Nice example here on the bench, a FT-101ZD did not have
any output, the problem was a dirty switch. Now it has
150 W pep, and the tubes are the first pair.
73 Kay DL5OAQ
Sure, but don’t just say “check the transformer”. Tell him
which point to which point—from the first solder joint to
ground, or whatever. Everyone is not a shop tech.
Some are just appliance operators.
Being very detailed works both ways...
Jaydee WA7PPF
[I really like this thought, Jaydee. Fixing a radio that’s not
if front of you takes a special knack. There’s certainly
room on this group for another file on ‘Helping People with
Radio Faults’ or something similar.
Anyone want to try? —John]
[This file is not owned by anyone. Feel free to add to it
and/or distribute it anywhere you please. If you want your
comments added to this version, send them to jpkiljan
AtSymbol yahoo.com —John (N0BUP)]
Our sincere thanks John for letting us use this file.
73, Wim PA0PGA
This manual was downloaded from Fox Tango International
Removing the Yaesu WARC bands TX disabling
modification on FT101 ZD MKII.
( N.B. The Yaesu Mod did not disable the RX for the WARC bands)
The Driver mod works by effectively adding extra capacitance from the lower bands across the coil, so that the WARC
bands cannot tune to the required frequency, and no drive is therefore produced for the PA.
This Mod removes the extra capacitance and the WARC bands can then tune correctly. There are no adjustments to make
after the wiring change. Takes about 15 minutes and you get three bands going.
a. Turn the FT101ZD over with the front panel towards you. The Driver section is on your Left hand-side half way up.
b. Remove the Driver section metal plate. Two of the lid securing screws will be hidden under some foam.
c. The S1E wafer is next to the PA section, which is at the Left hand side rear. The S1D wafer is in front of this one
towards the front on the unit.
d. Identify the 3 BLUE wires and a GREY wire all joined together on a spare hole at the top of the S1E wafer. The Blue
wires are connected to the S1D wafer.
S1E wafer
S1D wafer
1. Cut all the wires off the communing point on switch wafer S1E, 3 blue & 1 Grey wire.
2. Remove completely the grey wire to switch wafer S1D position 12 m.( best done by using long nosed pliers and
twisting it off )
3. Remove completely blue wire off switch wafer S1D position 40 m.
S1E wafer
S1D wafer
3 BLUE Wires
This manual was downloaded from Fox Tango International
a GREY Wire
Cut all
position 40 meter
30 m
17 m
4. Connect as a loop Blue wire on switch wafer S1D position 30 metre to switch wafer S1D position 20 m.
5. Connect as a loop Blue wire on switch wafer S1D position 17 metre to switch wafer S1D position 15 m.
30 m connected to 20 m as a loop
17 m connected to 15 m as a loop
6. End of modification.
Mario Chomicz (G8ODE) & Teruhiko Hayashi (JA2SVZ)
foam tape
Driver section metal plate placed
This manual was downloaded from Fox Tango International
VFO stability story
We all know about the Roaming Gnome. He’s the little guy who is
never still, but rather travels the world sending back post cards
from the numerous exotic places he visits, when in fact he should
be sitting still. Rock still, in the garden.
The gnome’s travels may be humorous but when your radio
frequency travels, all humor goes out the window. The dial is
supposed to stay put, just as the little concrete guy is suppose to
stay put.
A couple of years ago I obtained a very nice and very clean Yaesu
FT-902DM. Now this is one fantastic radio. Not only does it, unlike
so many other transceivers, have the power supply built right
inside the case, it covers all of the WARC bands - all bands from
160 through 10 meters - and operates all modes including AM and
FM. Great for 10 meter operation. I won’t outline all of the features.
Simply take it that it’s a very nice radio. It’s from an earlier era so
it does contain valves (ok, tubes for us on this side of the pond) in
the transmitter (driver and PA) so more “tuning” is required than
for current solid state rigs. Yes, the receiver is all solid state. It’s
been a fun radio to operate and makes a great rag chew rig for
such bands as 17 meters.
Alas, all is not perfect with this radio. It suffers from a bad case of
frequency drift. It requires a very long warm up time to stabilize
enough to hold comfortable QSOs. Naturally following a station
that drifts away from you while you’re trying to carry on a chat is
The drift is downward in frequency and amounts to several KHz
over a period of time, and is consistent on all bands. I determined
to resolve the problem by finding the source of the malfunction
and correcting it. I said that because some of the advice I received
when I inquired on a couple of Yaesu email lists was to take the
easy way out and simply get and use the external VFO which
mates with the rig. Now having that VFO is certainly ideal and
someday I’d like to get one but not for the reason given. The
external VFO would allow split frequency operation further adding
to the rig’s utility.
I monitored the output of the internal VFO and noted that it
increases in frequency. By the way, I must add that the drift is
heat related. With the filaments turned on and especially while
transmitting, the heat buildup is greater and thus the drift is
accelerated. That told me on thing. The VFO is using temperature
compensating capacitors and the compensation is too much. Surely,
it did not leave the factory in that condition, so one must presume
that the values selected for the circuit are correctly arrived at.
Probably, component values have changed with age. Something
has gone bad.
by Dan WB5TKA
The original complement of capacitors within the tuning portion
of the VFO, besides the variable ones, consisted of (in parallel) a
33 pf NPO, a 15 pf NPO, a 3 pf N750, and a 12 pf N750. A total of
15 pf N750 temperature compensation exist.
I ran a couple of tests. I removed both of the temperature
compensating caps. but to insure that the total capacitance
remained the same, I temporarily tacked in a 15 pf NPO. As
expected, the VFO drifted down in frequency. Remember, the VFO
had drifted higher in frequency originally. I then added only the 3
pf N750. The VFO still drifted up, but of course not as much as
with no temperature compensation. I needed more.
I replaced the 3 pf with the 12 pf N750 and now the drift is
downward again. Not nearly so much as at first. Now the drift is
much slower (less distance over time) and ends up no more than
about 1.5 kHz over a 12 hour or more time period. Not bad, but
still not good enough. Far from it.
By rights, something less than 12 pf and more than 3 pf of
temperature compensation is needed. Either a capacitance value
of perhaps even one of like capacitance but a lower compensation.
A N220 perhaps.
I don’t know what the final solution will be yet. My next steps will
involve some experimentation with different values of temperature
compensation caps. At the same time, I will be looking further
into the existing components seeking a clue about the real cause
of the problem. The caps. I’ve checked so far have measured very
close to their stamped values. That does not mean (if it’s possible
for this to happen) that one of the temperature compensation
capacitors has changed its characteristics. I’ll update this article
as work progresses.
August 13, 2004. I’m a week or two behind in adding this update.
The good news is that the radio is back to normal operation. I
removed the recently installed 12 pf N750 and put the 3 pf N750
back in. As before, the drift reversed direction. Drifting up in
frequency. I installed - mainly because it was the closest I had for
something less than the previously installed 12 pf, an 8.2 pf N220.
I’m not sure I could have come much closer had I a large
assortment of sizes to work from. Drift now for all practical purposes
is gone. After about an hour of warm up time, it’s up in frequency
only 300 Hz. The manual lists the stability as less than 300 Hz
after 10 minutes of warm up and less than 100 Hz after 30 minutes
I set the dial to read 14.275.0 (no particular reason for picking
that frequency) and after 24 hours, the frequency was rock solid
at 14.274.8. The warm up time included having the filament switch
on to help insure that the heat build up within the radio would be
similar at least to normal use. The 200 Hz change, I can live with.
It’s certainly a vast improvement over the original drift which would
have been perhaps a couple of kHz or more.
Now with the radio back in good working condition there is one
more thing I am going to have to attend to. The two PA tubes
appear to be soft. In the tune mode, the power after tuneup reaches
perhaps 90 watts but falls off within a few seconds to perhaps 60
to 70 watts. So an investment in a new matched pair of 6146
tubes is in order.
Questions? Comments? Contact me.
Article courtesy of Dan WB5TKA
More on his website: http://
This manual was downloaded from Fox Tango International
The 6146 Family of Tubes
Glen E. Zook, K9STH
Probably the most used tube of all times in the final amplifier of “boat anchor” transmitters
is the 6146. From the early 1950s until at least the 1980s, the 6146 found its way into
virtually every manufacturer’s line of transmitters. In fact, during the early 1960s RCA had
a series of advertisements on the back cover of QST that listed a different manufacturer’s
equipment that used the 6146 each month.
There are actually three distinctive variants of the basic 6146: The 6146, 6146A, and 6146B.
It is unfortunate that the 6146B was called the 6146B for it is really a different tube from the
first two. Primarily the difference between the “plain” 6146 and the 6146A is the makeup of
the heater (“filament”). The 6146A has what RCA calls the “dark heater”. This “dark heater”
is supposed to be more resilient to vibration, work well at a larger “range” of voltage, etc.
Otherwise, the 6146 and the 6146A are the same tube.
In mid-1964 RCA introduced the 6146B with the “claim” of 33.33 percent higher power
input than the 6146 / 6146A. Also, it was “claimed” that the 6146B could be directly substituted
for the earlier tubes. The 6146 / 6146A had a maximum rated power input of 90 watts for
CW and SSB operation and the 6146B had a rating of 120 watts for the same emissions.
Many amateurs are aware that the military “ruggedized” version
was designated the 6146W (I will get to these tubes a bit later).
However, RCA also introduced in the early 1960s the 8298 tube
for use in commercial mobile equipment. The 8298 is just a “heftier”
6146A. Motorola, General Electric, and quite a number of other
commercial FM equipment manufacturers used these tubes in all
sorts of FM communications equipment for both low band (30-50
MHz) and high band (150.8 - 172 MHz). When the 6146B was
introduced, RCA “announced” the 8298A commercial equivalent
of the 6146B. In fact, most of the RCA 6146B tubes were “cross
branded” with the 8298A number in addition to the 6146B.
Those companies who were manufacturing 6146 series tubes for
the military changed from the “plain” 6146 to the 6146A to the
6146B as the military decreed. However, all of the tubes
manufactured under military contracts were known as 6146W and,
to my knowledge, nothing was done towards marking the tubes
as being equivalents of the 6146, 6146A, or 6146B. The only way
of telling is from the “date code” which is printed on each tube.
Different manufacturers changed tube types at different times.
Also, I know of no “master list” telling on what date a particular
manufacturer changed from the 6146 to the 6146A to the 6146B.
The only “sure” way to know if a particular 6146W is of either the
6146 or 6146A type is to look for a “code date” of before 1964
since RCA introduced the 6146B in the middle of that year. However,
some manufacturers did not start manufacturing 6146B equivalent
6146W tubes for at least a year after RCA introduced the 6146B.
RCA “claimed” that the 6146B was directly interchangeable with
the earlier members of the 6146 family. Unfortunately, this did
not hold true in most cases. Collins, Heath, and probably other
companies, at first issued various documents saying that the use
of the 6146B in their equipment was “fine”. But, this soon proved
For example, when the 6146B was used in the Collins 32S-1, 32S2, 32S-3, 32S-3A, KWM-2, and KWM-2A it was discovered that
the components in the neutralization circuitry “burned up” in a
very short amount of time. Thus, Collins had to retract the statement that it was “OK” to use the 6146B. Then, due to the fact that
the United States military establishment wanted to “standardize”
on the 6146W equivalent of the 6146B, the neutralization
components had to be redesigned to allow the 6146B to be used.
Fortunately, these changes did not affect the use of the earlier
6146 and 6146A in those transmitters manufactured to use the
6146B. All three types of tubes may be used without any problem
in these transmitters.
Replacing the 6146 / 6146A tubes with 6146B types often results
in spurious emissions, parasitic oscillations, etc. This is due to the
fact that there are different bias requirements, different interelectrode capacitances, etc. of the 6146B versus the other two. It
is often difficult to neutralize 6146B tubes when used in place of
the 6146 / 6146A. If neutralization can be achieved, often it lasts
for just a few minutes before the tube(s) goes into oscillation.
If one insists on trying the 6146B tubes in place of the 6146 /
6146A types, the very first thing to do is to neutralize the final
amplifier. If it will not neutralize, then the 6146B tubes should
immediately be replaced with the older type tubes. If it does
neutralize, then the neutralization should be “watched” for several
hours (even days) of operation. If the neutralization changes, then
the 6146B tubes again should be replaced with the 6146 / 6146A
series. If the neutralization remains constant after several days,
then use of the 6146B is fine in that particular transmitter.
I have, in my shack, a number of transmitters that use the 6146 /
6146A type of tubes. These include Collins 32S-1, 32S-3 (earlier
model before the neutralization was changed); Heath Apache,
DX-100, DX-35, SB-401, SB-110, Seneca; Johnson Pacemaker;
and other transmitters as well. Every one is much “happier” with
the 6146/6146A type of tubes. In addition, I have owned
transmitters like the Knight T-150 and T-150A that use the 6146
tubes. Frankly, these transmitters were much happier with the
6146/6146A tubes.
This manual was downloaded from Fox Tango International
There is another 6146 family tube that is “superior” for operation
at least through 10 meters. That is the 6293. This tube was
designed for “pulse” service and is rated at 1-Kilowatt pulse power
input. The primary difference between these and the “normal”
6146 is that the plate is much “heavier” in its construction. Back
in the late 1950s and early 1960s we would almost “kill” to get
our hands on a pair of these for our DX-100s, etc. The 6293
outlasts the 6146 in “normal” service by at least 5 times and
often more than 10 times the life of the tube. These tubes “show
up” at hamfests, swap meets, etc., from time-to-time. If you see
some of these, definitely “glomp” onto them!
The 12-volt equivalent of the 6146 is the 6883, the equivalent of
the 6146A is the 6883A, and the 6146B is the 6883B. Now, there
are the tubes that were manufactured for FM commercial service.
These series go as follows: 6883, 6883A / 8032, 6883B / 8032A /
8552. Again most of these are “cross branded” with all of the
tube numbers that are equivalent.
From 1970 until late 1979 when Motorola went out of the
reconditioned equipment business, I owned the Motorola
reconditioned equipment center for the south-central United
States. We reconditioned Motorola FM equipment for 14 states,
everything that Motorola sold reconditioned that was exported,
and everything that was sold to the United States Government
(this was the height of Viet Nam and the Government did buy
reconditioned equipment!).
At that time, the Motrac series of mobile equipment was very
popular. Depending on the model, these normally used one, or
two, of the 6883A / 8032 tubes. It was only in the very “latest”
models (HHT “E” series, LHT series, and MHT series) that Motorola
had redesigned the equipment to use the 6883B / 8032A / 8552
tubes. Around late 1976 or early 1977, Motorola decided to
eliminate some of the tube types that they were “stocking” at the
Schamburg, Illinois, parts depot. Thus, they started shipping 8552
tubes in boxes that were marked as 8032. The Motrac is unique
in the fact that you cannot see the tubes when they are in
operation (they are enclosed in a metal “heat sink”). In fact, it is
difficult to even “tune” a Motrac when the heat sink is not in
We went through from 50 to over 100 of the 8032 type tubes per
week and within days were “down” to using the 8552 tubes in
the 8032 boxes. Within a very few days of starting to use the
8552 tubes we started receiving complaints that virtually every
Motrac unit that was received by customers arrived with one, or
both, tubes broken. Prior to this we had never had a single
complaint. Upon investigation we found that the 8552 tubes had
so many parasitic oscillations that they were getting so hot that
the glass envelope was being annealed! This was happening within
a minute, or two, of tune-up and final quality control. When the
radio was subjected to normal vibrations of shipping, the glass
envelope of the tubes was being shattered.
This was reported to Motorola. At first they refused to believe us
saying that we must have gotten a “bad” shipment of tubes. But,
within a couple of weeks they received over 1000 complaints from
their service stations about exactly the same problem. It cost
Motorola one “heck of a lot” of money to pay the warranty claims
because they had tried to “cut costs” by eliminating the earlier
type of tube. They had to re-box all of the 8552 tubes that had
been put into 8032 boxes and get in a “rush” shipment of 8032
The whole problem stemmed from the fact that the “B” series of
tubes is not the same as the “plain” and “A” series. The parasitic
oscillations were caused by the different bias requirements and by
the “fixed” neutralization of the driver and/or amplifier tube in the
Motrac. There was no practical way to change the circuitry to handle
the “B” series tubes. Also, making such a change would void the
“type acceptance” of the units.
In a “practical” sense, it is “OK” to mix 6146 and 6146A tubes
since the primary difference is in the design of the heaters. But,
NEVER mix 6146 / 6146A tubes with a 6146B! This is really “asking
for trouble”.
Also, in a number of transmitters and transceivers (especially the
Heath SB-Line) the heaters (“filaments”) of the pair of 6146 tubes
are in series. In these units it is very easy to change the heaters
from series to parallel and substitute the 6883 / 6883A / 8032
tubes. The 12-volt equivalent tubes are often available for “pennies”
because of the vast number that were used in the commercial FM
market. I have done this with my Heath SB-110A and it works “like
a champ”. If you every want to change back, it is a very simple
operation to do so.
I know that there are amateurs who say that they have used the
6146B tubes in place of the 6146 / 6146A without any problems. I
can definitely believe that. But, I have seen way too many examples
of the 6146B causing problems in relation to the cases in which
the substitution has no effect. As I said before, neutralize and
keep checking the neutralization for several days if you do replace
your 6146 / 6146A tubes with 6146B types. Otherwise, you can
find yourself with TVI, “burned out tubes”, and other damage to
your transmitter.
You must be VERY careful when dealing with the various tubes of
the 6146 family, otherwise you just might be in for some very
interesting problems. Substitute if you must, but, be aware that
you are “treading on thin ice”.
Copyright article: Glen E. Zook K9STH, reprinted with
his permission, tnx Glen!
More interesting articles on his website: http://
6146 type tubes and equivalents:
25W = 6293 (heavy duty pulse tube, 5-10x longer lasting)
25W = 8298
6883A/8032 (12V heater)
35W = 8298A
6883B/8032A (12V heater)
35W = 6146B
YL1372 (12V heater)
35W = 6146W
(fabricated as 6146B after 1962)
25W = 6146A
European version by Philips & Mullard
QE-06/40F = 12V heater, K = 13.8 V heater, H = 26V heater
This manual was downloaded from Fox Tango International
Buyers Beware
Be careful by buying any FT-101ZD transceiver with AM/FM and previously used on 27 Mhz by good
buddy’s, they have all been heavely overloaded by users that had no real knowledge what they are
doiing, so suspect the worst. They liked special the tube-type final sets, because they are not so easely
destroyed by misuse as the more modern sets with transistor PA’s.
When you buy such a transceiver, it will cost at least a couple of final tubes, at a additional cost of
around $ 100.-, if not the total repair of the Power Amplifier. It is better to pay something more for a
good-looking, not over-used set from a known source. The same goes for the FT-901DM, even more
popular with the CB folks because they had the AM and FM boards installed.
If the price is too good to be true, it usually is. Cheap sets are usually problem sets.
If you can repair everything yourself and have the time, there is nothing wrong with buying cheap, but
usually the sets are otherwise misused too, so you always end up with a lesser set than the one in good
condition, carefully used by a fellow ham. Of course this sets can also have some problems, but have at
least the potential to be restored to a first class piece of equipment. Use your common sense.
Always try to collect the set yourself, that way you can see what you are in for. Sometimes to meet the
vendor can give you a clue how the set was used.
Buying at Internet is a good source, if you take some precautions:
If the seller uses the internet much, he has usually a quality marking to his name, wich gives a clue to
his reliability, but this means also that he buys and sells very often, and is more interested in a quick
buck, than in the equipment itself. So please beware, and be careful. You see often the same pictures of
very nice equipment in ads, but when you receive it, is it a box full of junk, scratched and mostly with a
lot of internal problems. See the FT-901DM page for a sample.
The best buys come from local hams, or hams who want to upgrade to a newer ricebox with more menu’s and knobs to fiddle with. To obtain the new toy, they sell the old, reliable sets often for a modest
price. Another source can be the usual swapfest or estate sell fom a deceased Ham.
Of course you have to inform yourself on the market value of the set you are looking for.
Actual prices change with general condition, the available options or accessoires, and are often
negotiable. Take your time, and keep an eye at ads, sometimes you have to act fast if your dreamset is
at an auction for the right price. If you are in a hurry, you can always place a ad in the asked catagory.
6146 type power tubes:
Try to buy NOS tubes of American brands, I have a special liking for RCA tubes, but other good brands
are GE, Eimac, Tungsram, Raytheon or European Philips, Mullard, Siemens or Telefunken. All this firms
don’t make tubes anymore, but there are still much tubes on the market. Good tubes last practically
forever, if you use them properly, special the ruggidized types and SQ types in Europe.
They are in most respects much better than the Chinese and Russian and many other mysterious brands
that are on the market today.
A special warning may be worth the brands Haltron and Ultron. They were tube manufacturers in the
previous East-European countries and produced low-cost versions of all kind of popular tubes. They still
produced tubes when the other brands closed their factories. If you look close to the construction you
see skewed electrodes, balloons skewed in the sockets, and a general miss of quality. They never last as
long as the others. I prefer anytime a 50% tested secondhand RCA tube to a new Haltron.
Keep them glowing...
This manual was downloaded from Fox Tango International
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