[Hammarlund] SP-600 Advice/Help

Thu, 28 Nov 2002 20:01:04 -0600

I agree with Andy regarding the BBODs. But I will add this. The BBODs do not
need to be short circuited to cause problems. Most of the BBODs bypass a B+
supply to ground. Add up the additional load of 50 or so BBODs with 2 ma
leakage current (value picked from the clear blue yonder, but reasonable)
and you can see the additional load on the power supply (chokes,
transformer, etc.)
Before recapping my JX-17, I could not comfortably place my hand on either
of the chokes or the transformer after 30 minutes of operation. ( well, I
was stupid. what did I know?) After recapping, the chokes and transformer
are relatively cold after 30 minutes and only perceptibly warm after several
hours, but no longer at risk! Additionally, the added current tends to cook
the decoupling resistors in the rf, if stages.
Change them all!! I used disk ceramics (.01 uf, 1 kV) for all rf bypassing,
and orange drops for B+ decoupling and audio coupling. Works just great!

Be aware that several of the if transformers have these little beasties
inside the cans, as does the IF output housing, T1, on the power supply side
of the rf deck, and the rf deck itself.

Have fun.
Dick K9FFK

 -----Original Message-----
 From: [email protected]
 [mailto:[email protected]]On Behalf Of James A. (Andy)
 Moorer
 Sent: Tuesday, November 26, 2002 10:07 PM
 To: [email protected]; [email protected]
 Subject: Re: [Hammarlund] SP-600 Advice/Help

 ----- Original Message -----
 >
 > I have started restoring my first SP-600.
...snip...
 ------------------------------------------

 Your SP-600 has all the signs of one I did last year. If you look at the
 schematics, you will see that C164 and (I think) C165 and C162 are BBOD's
 that are directly from the choke output to ground. If one of those shorts
 out, it takes one or both of the chokes with it, and sometimes takes the
 power transformer as well. It is a real mess.

 The moral of this is NEVER, NEVER, NEVER power up an old un-recapped SP-600
 without replacing those capacitors, or at least disconnecting them.

 James A. (Andy) Moorer
 www.jamminpower.com

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