[Hammarlund] SP-600 Mystery

[Barry Hauser]

Hi Gang:

Another oddball SP-600 tracked me down.  I suspect I know what's what,
but just in case:

1.  The tag on the RF cover says "J-22".  Covers are swappable, so can't
tell if it's the original.
2.  Consistent with the missing "X" -- there is no crystal module,
however .... 
3.  Has a standard JX type panel with the holes and labeling for the
crystal control unit, but ....
4.  The two big chokes are mounted flush with the chassis and share a
long reinforcing plate with the transformer. (I think that's stock)  The
style matches -- all three are round, not hex shaped -- actually four
with the one toward the rear of the chassis (audio output xformer?  I
forget.).  It's possible the chokes were raised up for some reason. 
Normally, they are mounted on a heavy plate below the level of the
chassis, which provides room up top for the crystal module. Why would
someone go to the bother of removing a crystal module from a JX and raise
up the chokes?
5.  Here's the corker:  This came in a cabinet.  When I slipped the rx
out to have a look there were some wires hanging out -- two switches
dangling on their wires.  These are the two extra controls for the
diversity version -- like a JX-17.  The wiring and switches look
original.  No place for them to go as the radio has a regular JX
(non-diversity) front panel.
6.  There are a number of extra things on the back panel -- mostly SO-239
connectors -- a total of five, including one mounted on a very sturdy
bracket off one of the horns.  They are two extras and they aren't in the
usual positions.
7.  There are two additional (four altogether) screwdriver adjustable
pots.  Also an RCA jack.  One terminal strip looks stock.  Another --
alongside it -- appears added.  The spare fuse holder has been moved and
is mounted horizontally.  There's a pot with a small knob on it and a
slug adjustable coil, and a toggle switch.  In other works, it doesn't
look like this started out as a diversity model.
8.  The front plate of the tuning mechanism is drilled for the VFO/Xtal
switch and it looks like it was probably mounted there at one time.
9.  The can on the bottom of the chassis is missing but the phenolic
board is there and looks like its component count has increased somewhat,
as if the can wouldn't fit afterwards.

All the work seems to be very neatly done.  The panel is nearly perfect
and I suspect it was refinished or an NOS replacement.  Most suspicious: 
I think this is the first SP-600 that arrived with it's meter not loose
and rattling around.  Everything is clean, but still has the requisite
dead spider. Probably succumbed to terminal appoplexy.  These radio
sentinel spiders are purists.  They'd rather starve at their posts rather
than leave to get something to eat.  That's dedication.

Most likely this was a JX-17 that was modified, but that story doesn't
quite fit.  There are places on the rear panel where some SO-239's would
have been, but no holes.  Why would anyone go to the trouble to remove
the crystal subchassis AND raise up the chokes?  I can usually figure
these things out, but this one has me stumped.  There seemed to have been
a non-X diversity version with a big IF gain control where the Xtal
controls would be on a JX and no red knobs.  But this specimen doesn't
match that either.

Is there an SP-600 detective in the house?

Barry

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