Re: 40M band pass filter alignment - very little signal getting th...

[G3VVT]

 
In a message dated 12/02/05 20:13:17 GMT Standard Time, [hidden email]  
writes:

All of  the checks were in the expected range, except for U6
pin 8, which was 36.8  ohms instead of greater than 100 ohms


---------------------------------
 
Check that RFC14 on Q19 source has been fitted to the correct position.  
There is an adjacent ground through hole that if used by mistake will reduce the  
U6 pin 8 (8B rail) reading by 270 ohms as R20 then is effectively shorted  
out. Otherwise it is a matter of breaking down the direction of the loading of  
this reading. There are series resistors in some of the paths that can assist
to  this end.
 
Bob, G3VVT
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[Vic Dively]

Thanks everyone for the pointers, the problem is solved.

Bob, you were right on the RFC14 issue, I don't think I would have ever
noticed that hole, as it was hiding under RFC14.  After I fixed that, the
reading on U6 pin 8 jumped to 292 ohms, so that reading was now in line.
I re-did the alignments, and the audio volume was louder, but I wasn't
sure if I'd found everything - I was definitely picking up more signals,
but still not as good as the FT817.  Then Jeremiah, WA2DKG asked about my
C6 placement, and sure enough I had misunderstood the directions, and had
the capacitor in the far left two holes, instead of the far left and far
right holes...so I fixed that and turned it on again, and it sounds great
- lots of volume, and tons of signals out there, listened in on the low
end of 40M and heard lots of DX with my relatively small attic antenna,
so I'm quite excited - now on to to Assembly, Part III.

Thanks again everyone for the help, I hope to be on the air soon with
serial number 4311.  

73,
Vic  KG4HTT
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