- 15 -
eliminates the possibility of a long or marginal feedline influencing the tuning or causing erratic
readings. If necessary, tune the antenna for low SWR on 18.160 MHz. Normally, the SWR readings
go down somewhat and the bandwidth readings increases once the feedline is reconnected and you
measure the SWR at the operating position.
Adjustment of the low SWR frequency is done by slightly loosening the
wing nut holding the tuning rods and adjusting the length of the tuning
rods. Adjust both tuning longer to go lower in frequency or shorter to go
higher in frequency. Both tuning rods should be adjusted equally and
should not need to be adjusted more than a couple of inches. Make
adjustments in small steps. 1/2 in. of adjustment should change the
resonant frequency by about 75 kHz.
Typical 17 Meter SWR after tuning
The 17m add-on kit electrically couples to
the rest of the vertical and does have some
influence on the tuning of adjacent bands. If
retuning is required make minor adjustments
as necessary. Refer to the DX Engineering
BTV Installation and Assembly Guide
available from DX Engineering.
In some installations, particularly those with
very good soil conditions or a very good
radial system, the traps themselves may
have been changed from factory dimensions
during the initial installation of the vertical
to resonate the vertical in each band. In
those cases where the traps have already been adjusted, leave them as-is for now.
Check the vertical for low SWR on each band and note those frequencies. This will help determine
what adjustments are needed. After installation and tuning of the 17m kit, the BTV will likely be
tuned to about the same frequency in the 10 meter band and a little higher in the 15 and 20 meter
bands. No difference is likely on 30, 40 or 80 meters. In most cases, re-tuning to the desired
frequencies for each band can be accomplished by adjusting the tubing dimensions of each section
as described in the DX Engineering Hustler BTV Installation and Assembly Guide.
