[Heathkit] DX-40 question

[Jack Antonio]

On 9/25/2016 3:27 PM, Bill Cromwell wrote:
> Hi,
>
> He did say it will take off without even having an xtal in the socket. 
> That seems like feedback from the final to it's own input or to the 
> prior stage. And what about the screen bypass?
>

Thanks for the replies. I did some more work on the transmitter today, 
and made a little headway, but
haven't found the smoking gun (or guns, it could be multiple issues.) I 
went through and retightened
hardware, checked solder joints, but no change.

It appears that the driver is acting like a TPTG oscillator. On 40 there 
is a 7Mc tuned circuit on both
the input and output.  I added a shield between the oscillator and 
driver, and beefed up bypassing
on the driver, and it helped a little, but no firm cure as yet.

Also found that FT-243s with a metal cover were more prone to this 
problem than all phenolic or
bakelite ones.

Again, there are no problems on any other band, or with using 80 meter 
crystals on 40.

So still scratching my head on this, but am out of time for now. Will 
keep you all apprised
of what I find.

Still thinking that I saw this written up somewhere, but sure can't 
remember where.

Thanks

Jack Antonio WA7DIA/4
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>