Butternut TBR-160-S Instructions

BUTTERNUT Manufacturing Co.
Instructions
Model TBR-160-S
The TBR-160-S is a parallel tuned circuit that attaches to the base of BUTTERNUT vertical antenna models HF2V
and HF6V-X/HF9V-X permiting operation on 160 meters.
THEORY OF OPERATION
The TBR-160-S functions as an inductive reactance in series with the antenna feedpoint, loading the antenna
structure to resonance on the 160 meter band. On the higher bands the TBR-160-S produces decreasing values of
capacitive reactance, slightly raising the resonant frequency (by 300-400 kHz) on 80 & 40 meters. Above 7 MHz
this detuning is negligible, and the antenna may be adjusted to compensate. In general, the only compromise that
one must accept for the sake of 160 meter operation is reduced SWR bandwidth on 80 meters and to a lesser extent,
on 40 meters with the HF6V-X/HF9V-X. The TBR-160-S is rated at output power levels of 500 watts on CW and
1000 watts PEP SSB, although prolonged tune-up at these power levels should be avoided. Bandwidth for SWR of
2:1 or less on 160 meters will depend to a large extent on the efficiency of the ground system used with the antenna;
10 kHz is a typical figure with a fair-to-good ground system and a relatively short antenna such as the HF6VX/HF9V-X. With the longer HF2V, especially if top loading "umbrella" wires are used, SWR bandwidths of 15 to
35 kHz between 2:1 points are possible. Greater bandwidths are likely with poorer (higher loss) ground systems,
but the best possible ground systems should always be used with electrically short loaded antennas.
ASSEMBLY
Refer to the drawing and make sure that all parts are present before proceeding.
1. Locate coil A and clamp B. Pass a 3/4" bolt through the hole on the tab of clamp B. Holding the bolt tightly
against the inside of the tab, place the loop at the upper end of coil A over the threaded end of the bolt. Then,
place a washer and lock washer over the bolt and fasten snugly with a hex nut. The tab of clamp B may be bent
away slightly to insert a screwdriver in the head of the bolt to prevent its turning as the hex nut is tightened. Be
careful not to bend the coil during this operation.
2. Pass the lower coil clamp and then the rest of the coil over the upper (insulator) end of coil support tube C as
shown in the drawing, then pass a 1-1/4" bolt through the remaining hole in the coil end of clamp B. Use a
washer, lock washer and hex nut as shown to fasten that end of the clamp securely around the insulator end of
support tube C.
3. Similarly, install a washer, lock washer and wing nut on the lower coil clamp. Leave the coil fully compressed,
and tighten the wing nut only enough to hold the coil in place. You will adjust the coil later.
4. Locate the capacitor clamp D and slide one end of it up over the lower end of coil support tube C. Use 1" bolt,
washer, lock washer and hex nut to fasten this end of clamp D securely around tube C. Align clamp D so that it
is in the same plane as clamp B.
5. To install the TBR-160-S on the antenna, simply slide the freed ends of clamps B and D around the base of the
antenna as shown in the drawing and use 1-1/4" bolts, washers, lock washers, and hex nuts to hold the assembly
securely in place.
TESTING AND ADJUSTMENT
1. With the TBR-160-S installed as shown, the center conductor of the coaxial feedline must be moved from
thebase of the antenna to the coil end of clamp D. The remaining hardware should be used to fasten the lug of
the center conductor to the bolt holding the clamp around coil support tube C. Radials, ground wires, and the
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831 North Central Avenue Wood Dale Illinois 60191-1219 Telephone 630•238•1854 Facsimile 630•238•1186
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TESTING AND ADJUSTMENT
braid of the coaxial cable should remain attached to the mounting post. The top of the small impedance
matching/grounding coil ("Q") should be disconnected from the base of the antenna, but the lower end should
remain connected to the mounting post for possible use later.
2. Loosen the wing nut on the lower coil clamp and stretch the coil by sliding the clamp down tube C until the lower
edge of the clamp is approximately 4-3/4" (12 cm.) from the lower edge of clamp D. This setting should produce
lowest SWR between 1800 and 1900 kHz. Tuning is very sharp so SWR checks at intervals of 5 kHz may be
necessary to determine the resonant frequency with the initial setting. If no frequency can be found where the
SWR drops to a minimum value, simply stretch the coil out an inch or less, and begin another series of SWR
checks. Once the low SWR point has been found, it is a simple matter to make adjustments for any frequency
between 1800 and 2000 kHz. To raise the frequency of lowest SWR, stretch the coil a slight amount. To lower
the frequency, compress the coil. Final adjustments should be made with changes of 1/2" or less. For operation
above 1900 kHz it may be necessary to short out or remove several turns of the coil if it cannot be stretched
sufficiently.
3. After the TBR-160-S has been adjusted for 160 meter operation it will be necessary to readjust the 80 and 40
meter resonator circuits for greater inductance . Do this by compressing the coils for those bands. The circuits
for the higher-frequency bands should not require adjustment. In some installations, however, it may be found
that the previous 10 meter resonance moves to a lower center frequency and shows narrower bandwidth, while a
second unwanted resonance occurs in the 27 Mhz range. If the lower resonance cannot be moved above 28 Mhz
by shortening the upper section of the antenna (Model HF6V-X/HF9V-X), it may be necessary to neutralize the
27 Mhz resonance by shunting the capacitor across the lower few turns of the TRS-160-S coil. Should this
measure become necessary for proper 10 meter tuning, please contact our customer service department for
detailed instructions and appropriate materials. In the case of the HF2V, which is not designed for operation
above 10 MHz, this problem will not arise.
MATCHING CONSIDERATIONS
It is totally unrealistic to expect a perfect match to 50 ohm cable over the 1.8 to 28
Mhz range with a single antenna, because earth losses, antenna radiation resistance,
and conductor losses, all of which determine the feedpoint impedance of the antenna,
can vary greatly over the HF spectrum. With poor-to-fair ground systems SWR
resonance on 160 meters should be less than 2:1. With better ground systems, SWR
may exceed 2:1, although the antenna will perform more efficiently. In such a case, it
may be desirable to reconnect the free end of the impedance matching/grounding coil
to the feedpoint of the TBR-160-S and adjust for lower SWR. In general, however,
the reactance of this coil is not sufficient to keep 160 meter energy from passing
through it to the ground, even with the coil fully compressed, at settings that provide
the best match on 80 meters unless the feedpoint impedance is much less than 50
ohms, as would be the case with a good ground system. If necessary, additional
inductance may be placed between the base matching/grounding coil and the 160
meter feedpoint for the sake of a better match on that band. Unfortunately, the
amount of inductance that provides the best match on 160 meters will probably not
provide the best match on 80 meters, in which case it may be necessary to settle for a
compromise adjustment for both 160 and 80 meters.
HARDWARE PACKAGE
PARTS LIST
3 V00153 #10 X 1 1/4" Screw A V00339 Coil Assembly 160 Meter
1 V00131 #10 X 1" Screw
B V00267 Coil Clamp 160 Meter
1 V00226 #10 X 3/4" Screw C V00196 Coil Support Tube
6 V00132 #10 Flat Washer
D V00266 Capacitor Assembly 160
6 V00133 #10 Lock Washer
Meter
5 V00134 #10 Hex Nut
1 V00135 #10 Wing Nut
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