[AMRadio] Still more SP-600

Bill Smith hbco2 at sbcglobal.net
Fri Jan 12 01:56:08 EST 2007

Shotgun ideas (don't have a SP-600)

Check the actual oscillator frequency, which can be either above or below
the recive frequency.  The offset will be the same as the if frequency.
Sounds like the oscillator is tuned to the wrong side of the receive
frequency.  Either that, or a series capacitor which is connected to the
grid of the oscillator is the wrong value.


----- Original Message ----- 
From: Rick Brashear
To: AMRadio at mailman.qth.net
Sent: Thursday, January 11, 2007 7:46 PM
Subject: [AMRadio] Still more SP-600

I tried to post this to the Hammarlund list, but it is being held for
the administrator's approval, whatever that means.  So, I'll post it
here too in hopes someone will have mercy on me.

I am still having trouble with aligning the SP-600/JX-17.  I am
obviously overlooking something, but...  Here's where I am.  Tubes have
been replaced with known good ones.  I've tried several 6C4's with the
same result.  I have replaced all paper capacitors in the rf/oscillator
strip.  All resistance's and all other capacitors in the strip he been
tested and are well within tolerance.  The RF chokes are good.  In fact,
all components in this section have tested good or have been replaced
with good parts.  The capacitors in all oscillator modules in the turret
have been thoroughly checked, replacing any paper capacitors or out of
tolerance parts.  The voltages check well within tolerance as per the
manual.  The IF alignment has been made.  The problem is the oscillator
alignment is not wide enough to stretch the entire band on any of the
bands.  If I get it right on the bottom it's off at the top and visa
versa.  Same problem I have had since I began this project.  Am I
missing some obscure adjustment?  I've performed the alignment procedure
exactly as described in the manual.

Since everything is right (and I have checked it all twice and some of
it more than that) it must be me, but I can't find out where I'm going
wrong.  Any and all suggestions will be greatly appreciated.


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