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MODS FOR FT-23 / 73 / 211
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IZ5CCV
9600 BPS with Yaesu FT-211RH
---------------------------RX AUDIO:
--------On the RX "IF UNIT" (sub board F2869104) connect the screened lead
inner to
the TK10420 IC pin 9 with the outerscreen to pin 15. Caution should
be taken to
solder these if soldered to the underside of the board.
TX AUDIO:
--------On the rear of the "MAIN UNIT", a small potentiometer will be seen
(peak devia-tion adjust.). Unsolder the leg nearest to the rear of the set,
and connect
the inner of the screened TX leads to this point, the outer to the
earth plane
adjacent to this point. To ensure that the 9600 bauds modem is
terminated in
the required impedance, it is essential that a suitable terminating
resistor be
placed across the screened lead inner/outer (a 560 ohm resistor);
this may
usefully be done at the FT-211RH potentiometer connection.
No further adjustments need to be made to the radio. On the tested
modem a
suitable level of 2.5 kHz deviation was achieved with one third
rotation clock-wise of the modem TX AF level potentiometer.
YAESU FT-23R case disassembly:
-----------------------------1)
2)
3)
Remove the black screws from the top panel of the radio.
Remove the knobs.
Remove the black screws from the rear panel of the radio.
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4) Remove the battery.
5) Remove the 6 screws on the bottom of the radio, where the
battery attaches.
6) CAREFULLY remove the front panel of the radio.
7) In the left of the microprocessor and battery are several
printed circuit
jumpers. The jumpers labeled 7, 8 and 9 are for the frequencie
mods, like
explained in the following.
8) Re-assemble the radio in the reverse order of these steps.
9) The Microprocessor will loose all what the memory contains.
YAESU FT211/23/73 band mods:
---------------------------The uP's in the FT-23/73 and the FT-211 can be set for many
frequency and
memory mode combinations. These modes are controled by the jumpers
(solder
pads) marked 7,8 and 9 on the "CONTROL UNIT" board of either radio.
Here is a
list of what is possible:
7
JUMPER
8
9
open
open
in
in
open
open
in
in
open in
in
in
open in
in
in
open open
in open
open in
in open
FREQUENCIES
COVERED
140
140
144
144
220
440
50
430
to
to
to
to
to
to
to
to
164
160
148
146
550
450
300
440
MHZ
MHZ
MHZ
MHZ
MHZ
MHZ
MHZ
MHZ
The FT-211 has separate VCO's for transmit and receive and will
lock over about
38 MHZ from approx. 130 to 180 MHZ. The FT-23 has only one VCO and
the overlap-ping lock range (Xmt & Rcv) is about 25 MHZ from approx. 135 to
175 MHZ. Don't
forget, if you adjust the VCO you must realign every electronically
tuned stage
in the front-end of the radio. The transmitters can be tuned for
somewhat
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higher power output above 164 MHz but at a great power loss at 2m.
The non-amateur (commercial) memory mode will cause these functions
changes:
1.When in the MR mode, the channel number will be displayed
instead of fre-quency. You can toggle back to the original "amateur" mode
display by pres-sing F<up-arrow>. Pressing F<down arrow> bring you back to
commercial mode.
However, when switching from D to MR, the display will always
revert to the
commercial mode.
2.The function of the Dot<Pri> button will be exactly reversed.
That means now
you can press just one button (Dot) to get into or out of the
Primary function
The Pri funtion (in memory mode) will be indicated by a large "P"
on the left
side of the display.
3.The only indication of low power operation is in the memory
mode. A "C" will
appear in the upper left corner of the display (where the primary
"P" used to
be). The bargraph will always read 100%.
4.The band scan is now even more useless. The uP will painfully
count from 50
to 300 MHz.
FT23/73 in packet-radio:
-----------------------If you want to work in packet-radio, open jumper 10 to dissable the
battery
save.
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