All,
I ran into another hurdle with the SB-220 and am hoping someone has some
wisdom. If I run RF through the AMP without power applied the relative power
meter works and I can match my dummy load without issue. Side note, is the
relative power meter supposed to line up on the bottom scale with actual
forward watts? Ie: 100 Watts = 100 on the multimeter scale? Once I enable my
rigs “amp keying” mode and transmit with anything from tune mode to a carrier I
see high SWR and 0 output after the amp.
To troubleshoot, I hooked up my DMM and triggered the keying interface so that
the relay(s) engaged. I’ve confirmed that both are working correctly. Oddly if
I put the DMM in continuity test mode and trigger the TX mode on the amp I get
a beep. So, the RF is blocked someplace inside the tank circuit or band switch?
That’s my best guess. Or is it possible that a bad tube would cause these
symptoms? There is no deflection on the plate meter when I’ve put RF in. Does
that mean the tube is being held in cutoff?
Thanks for the help again. It’s challenges like this where I wish I had a local
elmer to help out!
-Warren KD5YPH
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