"Antonio Vernucci" wrote in message
...
Testing, my ART-13, I can obtain a good match on 7 MHz, 10
MHz and 14 MHz, with the antenna switch (control C) on
position 11 or 12.

But when I try to operate on 3.5 MHz, I am unable to
obtain a good match at any antenna switch position. I can
get roughly half the RF power with a higher plate current,
this indicating that match is poor. Grid current is OK.

At switch position 8 and above the matching network is a
Pi; at position 7 and below it becomes a simple L.

I know that the transmitter was designed to match short
(capacitive) antennas, and it may then not like the 50-ohm
resistance of my 80-meter dipole. But before carrying out
further investigations, I would like to hear if somebody
had experience in operating the ART-13 on 80 meters.

Thanks & 73

Tony I0JX
Rome, Italy

P.S. I do not succeed to get enough grid current at 18.070
MHz that is at the very extreme of the transmitter
operating band
Are you testing into a dummy load?
If you have an antenna impedance bridge you may be able
to measure the effective impedance of the output stage. If
the transmitter is operating normally you may need some sort
of external tuner.
--
Richard Knoppow
Los Angeles
WB6KBL