[Hammarlund] Speaking of manuals for SP-600...

[James A. (Andy) Moorer]

OK, folks, here is my eternal work in progress:

http://www.jamminpower.com/PDF/SP-600IdentificationGuide.pdf

It answers some of these questions (and raises a bunch more).
The JX-nothing (is that a "JX non-1"?) is a JX-1. They didn't have to call 
it a JX-1 until there was a JX-2, so the first ones just said "SP-600JX".

It is pretty much described in Issue-1 and Issue-2. It is mostly described 
in Issue-3, except that the RF deck in the early models lack a bit of the 
screen bypassing that is shown in Issue-3 (I need to add something to the 
Identification Guide talking about that). It is also mostly described in the 
Army manual TM 11-851 in Figure 99, as well as the Air-Force manual 
AN-16-45-222, although there are some differences. Some of the early manuals 
had small resistors that were called R72 and R73 that were just used to make 
sure the filter capacitors were discharged when the power went off. It is 
doubly confusing since later, big, hulking multi-watt resistors were 
installed to stablize the screen voltage of the IF strip tubes and they 
called them R72 and R73 as well (but your unit won't have those and it 
probably doesn't have the small R72/R73 either).

Actually, if you are inside the RF deck, you should put in the extra screen 
bypassing that the later models have, as shown in Issue-4 in the second set 
of schematics. It has a couple of extra bypass resistors and capacitors 
(although I can't hear any particular difference, but it seems like a good 
thing to do - all the subsequent receivers have the extra bypassing).

In addition, some of the early ones have the red-white wire and the 
blue-white wires from E13 to the RF deck swapped (described in Figure 7-4, 
page 62 of AN-16-45-222), but I don't think yours will have that one either.

Having said all of that, yours might still have a couple of small changes 
that I haven't covered. My impression is that you are best off to get copies 
of ALL the manuals - there is generally no one manual that perfectly 
describes any particular receiver. Bummer. If you balance about 3 different 
manuals on your knee, you can generally figure out what is going on. Luckily 
the alignment procedure is the same for all the receivers.

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

----- Original Message ----- 

>I have what appears to be an SP-600-JX, since that is what
> the nomenclature plate rivited to the top of the main tuning
> capacitor says.
>
> S/N is 2631.
>
> Am I correct in assuming that this is a JX-1? Or is it simply
> a  JX? JX-0?
>
> Which manual would be the correct one for this?
>
> I would like to start restoring it this coming fall, and would
> like to have all my waterfowl in a linear relationship by then.
>
> I have not attempted to turn it on, since I am seeing quite a
> number of gray tubular capacitors with a color code on
> them, which I assume are the GLODs (Gray Ladies Of
> Death) which have been spoken about here once in a
> while.
>
> Anyone have any suggestions to offer?
>
> Andy?
>
> Ken Gordon W7EKB