[Milsurplus] GRC-9 Drive Problem

[Roger Basford]

Hi All,

I have been chasing a drive problem on my AN/GRC-9 transmitter, the drive 
falls off with increasing frequency and is especially bad on 40 metres and 
above. The drive levels even down on 2 Mc aren't very good with an RF output 
of about 5 Watts on CW. The PA protection circuit kicks in when the VFO is 
used on the highest band but stays out on crystal control, although RF 
output is only 3 watts or so and I would guess there is a common problem to 
both VFO and crystal circuits, possibly an interstage coupling cap or 
biasing resistor. In view of the tight space under the tubes to make 
component substitutions has anyone had a similar problem that might assist 
my repairs? I've tested all tubes in the TX, the test socket voltages look 
about right and there's no obvious overheating or corrosion of components. 
I'm running off a DY-88 PSU on 24 V storage batteries.

Any input appreciated!

73,

Roger Basford, G3VKM (Norfolk, England)



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