[Hammarlund] SP-600-JX-6 fixed!

[wb3fau55 at neo.rr.com]

Thanks for your input guys!  Yes, this JX-6  had  me going crazy  for a while.  When I came across the mod sheet order for diversity operation,  I got a lot of answers.  
  Point  was made about real good sensitivity on low bands,  yes I see that.  This  is a real DX machine on the BC bands.  But its still really good on the upper  bands  including 6 meters.  I went thru the usual cap replacements and alignment.  Found one new issue for me-  bad oil tub caps, all open.  Never seen any of these go bad.  
   Can anyone offer advice on installing a nuvistor [6DS4]  in place of the 1st RF amp?  Is it worth the effort?  Do I need to just  make a socket adapter?  
---- David Wise <David_Wise at Phoenix.com> wrote: 
> I wish I could compare your radios to mine, side by side.  I definitely did have an overloading problem, which I diagnosed and fixed.  I hope my notes will be of some use to others.

Here's my own procedure for identifying which manual Issue to use.  I derived it by comparing schematics.

Dave
________________________________________
From: Les Locklear <leslocklear at hotmail.com>
Sent: Monday, August 21, 2017 11:19 AM
To: David Wise; wb3fau55 at neo.rr.com; hammarlund at mailman.qth.net
Subject: Re: [Hammarlund] SP-600-JX-6  fixed!

I've never experienced any overload problems except with the JX-17 variant which has the worst AC characteristics of any of the P-600 series. The best imho is the JX-14.

My present SP-600, a John R. Leary SP-600JX-21 has none of those problems, but it has a different AGC section and audio section.

To identify the various differences in the different models see the attached file which outlines the differences between the RF Decks and wiring, etc.

Les

Everyone has a photographic memory.
Some people just don't have film.
..Unknown..








----- Original Message -----
From: David Wise <David_Wise at Phoenix.com>
To: <wb3fau55 at neo.rr.com>, <hammarlund at mailman.qth.net>
Sent: 8/21/2017 10:49:23 AM
Subject: Re: [Hammarlund] SP-600-JX-6  fixed!
________________________________________________________________________________

<snipped for brevity>

Regards,
Dave Wise
SWL in Portland Oregon

________________________________________
From: hammarlund-bounces at mailman.qth.net <hammarlund-bounces at mailman.qth.net> on behalf of wb3fau55 at neo.rr.com <wb3fau55 at neo.rr.com>
Sent: Monday, August 21, 2017 5:58 AM
To: hammarlund at mailman.qth.net
Subject: [Hammarlund] SP-600-JX-6  fixed!

So I came across a CD containing a lot of SP-600 info.  There I found an answer  to the mod done with the meter adj pot.  As wired,  it controlled IF gain.  Rewired to stock,  problem now gone.  A bit of overload on local signals,  but lowering RF gain does  the job there.  wb3fau
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