[Heathkit] HG-10B Question

[Frank Sippel]

Check this if you haven't already done so...

Earlier VFO's had a 25uH RF choke in the plate lead.  Heath eventually 
changed this to a 350uH RF choke on later units.  The 25 uH choke 
resulted in low output on some bands and an unusual knee in the output 
waveform when viewed on a scope.  I didn't have a 350 uH choke but 
replaced the 25 uH choke with a 1.1 mH choke.  The latter is the cathode 
choke from a junker HG-10.ck this if you haven't already...


On 2/27/20 9:00 PM, Mark K3MSB wrote:
> Gents
>
> I'm troubleshooting a friends HG-10B.   The output is as expected on 40M
> through 2M,  but the output on 80M is about 7.6 MHz -- which is of course
> VERY wrong.
>
> I isolated it down to the 6CH8 tube.   On 80M,
>
> Pin 7:  3536 KHz 1470 mV PP -- Very nice
> Pin 2:  Really ugly waveform
>
> The frequency changes when turning the VFO.
>
> The DC voltages (in SPOT) are as expected:
>
> Pin 2 108V OK
> Pin 3  95 V
>
> Ocams Razor says it's the tube,  and of course I don't have any in my boxes
> so I have to order some.   So, in the interim,  I thought I'd post to the
> group and see if anybody has any suggestions while I wait for the tube.
> The unit is very nicely built and very clean.
>
> 73 Mark K3MSB
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