HW100 VFO output tweak

Dick KF4NS kf4nsradio at VERIZON.NET
Thu May 6 11:39:51 EDT 2010


A while back when I was doing all the troubleshooting and repair on my
radio, I came across a VFO troubleshooting chart in the manual.

It says if output is low after calibration, to fix the problem, tweak
the top core of VFO coil (part FM) for max output. It was not fun
doing the entire VFO alignment again after I screwed it all up. For
one thing, they say to adjust the "top core of coil FM" but there
seems to be only one core(?).

Has anyone tried this cure for low output (80W) on an HW100/101? (I 
have
been through all the other cures)

The VFO amplifier tube has been replaced with a new 6AU6, but I did go
ahead and test the output of the VFO and the test  is a bit low when
checked on my scope (5.17v P-P, 1.827vRMS) and is supposed
to be 3V RMS. I am assuming that even though they say it is read with
a VTVM RF probe which should be RMS, my calculation should be correct
unless my scope probe is loading it down. That should not be the case
if using a VTVM RF probe does not load it down. There is a caveat that
says "RF voltages may vary 25%".

Actually I thought some time ago that tweaking the output xfmr (one
with the taped hole) would be the better choice but I never had the
 you-know-whats to try it.

73, Dick KF4NS
St Petersburg, FL 33714 USA
Keep The Glow!

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