831 North Central Avenue Wood Dale Illinois 60191-1219 Telephone 630•238•1854 Facsimile 630•238•1186
V00237-092499
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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 HF6V-
X/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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