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From: parnass@cbnewse.att.com (Bob Parnass, AJ9S)
Newsgroups: sci.electronics
Subject: Re: Radio Electronics Descrambler
Summary: unreliable oscillator often means misalignment
Message-ID: <1990Dec19.173709.19066@cbnewse.att.com>
Date: 19 Dec 90 17:37:09 GMT
References: <1990Dec17.184710.28481@csn.org> <1990Dec19.112229.1@bunyip.enet.dec.com>
Distribution: na
Organization: AT&T Bell Laboratories, Naperville, IL
Lines: 28


In article <1990Dec18.224950.7142@usenet@scion.CS.ORST.EDU>,
harrist@jacobs.CS.ORST.EDU (Tim Harris) writes about debugging
a home built analog circuit:

 > 	the one who really knows what he's doing).  My brother poked
 > 	around the board with his finger and BAM, it locked up and was
 > 	working pretty good but unfortunately when you unplug it you have
 > 	to poke at it again to jump start it.  At that point we took it
 
I don't know if your project employs an oscillator with a
tuned circuit on the oscillator output.  If it does, the
tuned circuit should usually be aligned off to the side of
the slope, NOT peaked for maximum signal from the oscillator.

I've found that adjusting such tuned circuits for maximum
signal tranfer often loads down the oscillator so it won't
start oscillating reliably when power is applied.

My first experience with this was on a tube-type 2 meter
ham transceiver (Knight Kit TR-108) back in 1960s.
I finished building and aligning it.  When I turned it off
then on, the thing wouldn't work and I'd have to realign
the darn thing again to get it to work.  The problem was that I
was tuning for maximum local oscillator output.
-- 
============================================================================
Bob Parnass, AJ9S - AT&T Bell Laboratories - att!ihlpy!parnass (708)979-5414