[Hallicrafters] SX42 restoration notes

[Pagel, Mike]

Greetings, everyone!
 
This exchange about the SX-42 provides a perfect example of the value of this discussion group.  The accumulated wisdom of many experienced subscribers is amazing, and I wish we could bottle it.
 
The problem is that we can't.  The messages that appear on this reflector remain in the archives for 30 months, and then they go to the bit bucket.  
 
I'm interested in exploring any avenues for organizing and preserving the "good stuff" that keeps us all subscribed, but my enthusiasm for the task exceeds my knowledge of how to proceed (not unlike my interest in Hallicrafters receivers?).
 
Any suggestions out there?  
 
73, de Mike, K9UW
Amherst, WI
 
 

	-----Original Message----- 
	From: Barry Hauser [mailto:barry_hauser at juno.com] 
	Sent: Sun 1/5/2003 8:21 PM 
	To: jhanulec at mail.portjeff.net 
	Cc: hallicrafters at mailman.qth.net 
	Subject: Re: [Hallicrafters] SX42 restoration notes
	
	

	Hi Joe --
	
	Verrrrry interesting!  There's a tendency to focus on the paper tubulars
	and electrolytics.  Meanwhile, seems to be a growing trend toward bad
	micas.  Maybe the 50 year warranty ran out. 
	
	Your post should be put up on one or more of the web sites along with the
	other restoration stuff.  Do you think a cap checker would have caught
	these -- tested at rated voltage?  I seem to recall a post somewhere that
	said a 20 meg scale wasn't high enough -- a megger is needed on a higher
	range and the needle still shouldn't budge.  Not sure though.  If they're
	difficult to test, then they probably should be added to the routine
	replacement list along with the waxworks wonders.
	
	Are CM05's silver micas?  Where'd you get 'em?
	
	Many thanks!
	
	Barry
	
	
	
	On Sun,  5 Jan 2003 19:18:00 -0500 "Joe " <jhanulec at mail.portjeff.net>
	writes:
	> After changing all the wax coated paper capacitors and all the out of
	> tolerance resistors the radio still lacked gain even though all the
	> IF and RF coils peaked.  All the tube voltages measured nominal so I
	> tried replacing the mica capacitors in IF can T3 which seemed to be
	> most deficient.  The improvement was a surprising 10 dB at 455 kHz
	> and 6 dB at 10.7 MHz.  After changing capacitors in the other two IF
	> cans, the receiver become "alive" and a real performer, even though
	> I didn't pick up as much gain with T2 and T1.  The mica caps that
	> were removed didn't measure any leakage on a 20 Meg scale so I can
	> only assume that the ESR was the problem.  Apparently the ESR was't
	> bad enough to show up as inability to peak the tuned circuits.  The
	> 455 kHz coils are very delicate and made up of very fine litz wire,
	> don't break any of the leads as I did.  I used CM05 mica capacitors
	> for the replacement.
	>
	> Now I'm close to the specification of 60 uv for S9 at 14MHz.  I say
	> close because the S meter which is speced at 5 ma FS actually is
	> almost 7 ma FS.  Does it need a magnetic jolt?
	>
	> The receiver is a delight to use on both AM and FM especially with
	> the sweet audio from the P-P 6V6's and R42 speaker.  
	>
	> Now I need to do the same on my SX62 which has low FM gain.
	>
	> Joe Hanulec
	>   
	
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