MFJ-1792/1793 Instruction Manual
Vertical Antenna
13
80 m: 1" trimmed off a spoke equals
approximately
10 KHz
WARNING
:
Shortening the spokes from the looped end will affect the
performance of the antenna and degrade its power handling capabilities.
If the resonant frequency on 80 meter is lower than your equipment can detect, take
one spoke off the capacitance hat to raise the resonant frequency. Measure the
resonant frequency again. Estimate the approximate resonant frequency as if the
spoke was in place using the information above.
Example: The antenna measured 3.47 MHz, the desired frequency is 3.95 MHz (less .05
MHz) for a difference of .43 MHz or 430 KHz. This would require the trimming of 43"
from one spoke. Instead, cut 4.3 inches from
all six spokes
and measure the new
resonant frequency. Assume the new resonant frequency is 3.82 MHz. A single spoke
can now be trimmed 8" to adjust the antenna to resonance.
20 Meter Band
The 20 meter band is tuned by lengthening or shortening the threaded portion of the stubs.
This adjustment is very coarse. If frequency is too low with the stub element extension at
minimum, the unthreaded end of the stub can be trimmed.
TECHNICAL ASSISTANCE
If you have any problem with this unit first check the appropriate section of this manual. If
the manual does not reference your problem or your problem is not solved by reading the
manual, you may call
MFJ Technical Service
at
601-323-0549
or the
MFJ Factory
at
601-323-5869
. You will be best helped if you have your unit, manual and all information
on your station handy so you can answer any questions the technicians may ask.
You can also send questions by mail to MFJ Enterprises, Inc., 300 Industrial Park Road,
Starkville, MS 39759; by Facsimile (FAX) to 601-323-6551; or by email to
[email protected]. Send a complete description of your problem, an
explanation of exactly how you are using your unit, and a complete description of your
station.
