[Hammarlund] Re: Crystal filter for SP-600

[Kenneth G. Gordon]

I am finding this discussion extremely enlightening.

Many years ago, my Elmer, Woody Davey, W7CJB spent 
considerable time rebuilding an SP-600.

It took him a couple of weeks to get the crystal filter operating as 
he knew it should. I remember him expressing a lot of puzzlement 
at how it was supposed to be aligned, and how pleased he was 
when he finally worked out a method that worked. 

He was the head of the electronics part of the FAA in Missoula, 
Montana, and was a first-class electronic genius. He was one sharp 
cookie, and a first-class gentleman to boot.

About the only thing I remember of what he said concerning the 
crystal filter was that the "S" meter reading should INCREASE on a 
signal tuned in properly in the center of the crystal filter passband, 
since the signal-to-noise ratio increases as the bandwidth is 
narrowed.

I also remember that he told me that the method used in the 
manuals he had available then wasn't strictly correct.

I was only about 14 at the time, and I am 65 now, so my memory of 
that incident is pretty fuzzy.

Ken Gordon W7EKB