[Hammarlund] SP-600 double conversion question

[Craig Roberts]

Thanks to my vast experience with these machines (I've worked on a grand 
total of two), an old ham buddy sent me his dusty, dottering SP-600 JX 
to go "under the knife" last week. This one had been recapped, but the 
original restoration artiste simply tack-soldered the new caps onto the 
old BBOD leads.  Innumerable flaky and cold solder joints necessitated a 
complete re-solder job with proper mechanical connections being made 
this time.  This was MUCH worse than starting from scratch.

But, I digress (as I vent). Finished at last, I bolted the reworked FCU 
and RF deck back into place late (late, late) last night and powered up 
the receiver.  A few moments of panic were followed by blessed relief as 
I discovered I had thrown my antenna switch into the grounded position. 
CW and MCW signals appeared in their proper places prompted by proper 
switch positions, the BFO beat frequencies savagely, the AVC controlled 
volume (eventually), all selectivity positions were operative and 
appropriately restrictive, the crystal phasing control attentuated 
interference (sort of) and even the noise limiter did just what we have 
come to expect it to do (nothing).  All in all, it worked as an SP-600 
should.  Except....

The bands from 7.4 MHz and up (the double conversion bands) are a bit 
weaker than the single conversion ranges -- by about 6-10 dB. My own 
receiver shows a fall-off, too, but not quite as much.  Can this be normal?

And one other thing...  In aligning both sets, I have to crank the slug 
of L31 all the way in to get a peak reading during the 3955 KHz IF 
tweaking.  I tore open the transformer pod on both receivers and 
replaced the mica caps tied to the coils, but no difference was noted.  
Any ideas?  Maybe my alignment procedure is incorrect. I'm going by the 
book (Issue 4)

Any enlightenment would be appreciated greatly.

May thanks and 73 again,

Craig
W3CRR