Help on weak modulation for a Heath SG-8 siggen

[Richard Post]

Suggest first checking the two caps that go to ground from either 
side of the audio frequency choke.  If they are leaky, the symptoms 
will be as described. Been there.

If the external mod input works OK, then the following should not apply.
Clean the mod switch contacts.  Dirty tube contacts on 6C4 or weak 
6C4 are possible but less likely.  Finally, check for any wiring 
error or bad solder joint.  It may never have worked properly.

I was 14 when I built my SG-8. Used it occasionally as a wireless
broadcaster.  Picture at:


<http://oak.cats.ohiou.edu/~postr/bapix/Heath_SG.htm>


Rich KB8TAD




At 8:45 AM -0500 11/12/05, Ray LaRue wrote:
>I purchased a clean, used SG-8, the RF output is fine, but the 
>modulation is very weak.  The audio oscillator works but on a scope 
>it looks like about 5 or 10%. It can barely be heard thru a 
>receiver.  The manual isn't much help in troubleshooting the 
>problem.  Voltages look nominal.
>
>Anyone have any experience with it, that could offer some suggestions?
>
>Your attention is appreciated.
>
>73,
>Ray, W4BYG
>Naples, FL

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