Specifications

SMARTUNER MANUAL 52
SGC Inc. SGC Building, 13737 S.E. 26th St. Bellevue, WA. 98005 USA
© Nov2000 SGC, Inc. P.O. Box 3526, 98009 Fax: [phone] Tel: [phone]
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As part of your check-out of an HF system, you should operate on all channels and
frequencies which you plan to use on a regular basis to insure the coupler and antenna
which you have provided work well.
Antenna insulators. Sporadic operation may be caused by poor antenna insulators. We
have seen on sailboats, for example, people trying to save money by expecting the
fiberglass hull to act as an insulator and not using a lower insulator. The hull is not a
good insulator and a thin layer of wet salt water will degrade the ground further.
Similarly, mobile HF users who rely on a poor quality ball-mount find these are
especially prone to arc over inside the ball mount where it is difficult to detect.
The point we are making here is simply this: you should have a leakage path of 2 inches
at all points on your antenna and especially in the area of the feed point: 10,000 to
30,000 volts of RF energy will not be adequately confined by inexpensive insulators.
11.3 Transmitter Faults
Some vexing problems don't relate directly to the antenna or the ground system but
may nonetheless cause difficulties. Here are two of the most common types:
Oscillation. The transmitter may have a tendency to oscillate. The general symptom is
that the coupler will work well with another radio but will not tune correctly when the
desired radio is in place. The coupler finds a tuning solution, as indicated by the remote
tune indicator going on, but then resumes hunting. In a majority of cases this will be
caused by an overly sensitive transmitter final amplifier section or by inadequate
shielding around the amplifier.
We know of several radios that oscillate relatively easier than most radios because they
are housed in a plastic case. A plastic case does not provide an adequate shield for
serious RF components. In some of these cases, putting grounded foil around the radio,
or changing the radio location and orientation, has changed the symptoms. But if you
want quality performance, select a solid radio.
Power supply. Power supplies have been known to cause problems for HF users
because they change voltage when the load on them changes. If the transmitter is
drawing heavy current, as transmitters do when they are running at peak input power,
the voltage to the antenna coupler may change enough to cause the coupler to either
drop into a reset mode (under +11 VDC being present) or, the transmitter final
amplifier impedance may change greatly, thus changing the tuning solution.
To alleviate this condition, remember to use a power supply that has both adequate
current handling capacity and good dynamic regulation. Better yet, use a regulated
power supply of an adequate rating.
11.4 A Final Pointer on Troubleshooting