[Hammarlund] SP-600 update

[GBrown]

As most of you know, I was in the process of a restoration of a SP-600JX1.
The restoration went fine and looks good. I wasn't totally satisfied with
the performance on the higher (double conversion) bands.
In my opinion there was a lack of sensitivity and selectivity. I decided to
dig a little deeper into this fine piece of history and was amazed at what I
found.
For you SP-600 owners, you mite want to pursue this part replacement. After
hours and hours of troubleshooting and checking and rechecking components, I
come to the conclusion that the turret assembly had to come back out. Reason
is I had to get at L-31. There is a capacitor ( C-67 ) across this
capacitor. The value of mine is 85 mmf. I pulled the unit apart and unsolder
the cap. I then put the cap on my trusty Heath cap checker and carefully
watched the eye tube. It would flutter just a bit as if it wanted to close
up then reopen. It wasn't much of a flutter. I didn't want to take any
chances of having to remove the turret assembly again so I replaced the cap
with an 82 mmf, silver mica that tested good on the Heath tester. After
reassembly and readjustment of L-31, 20 meter cw and the phone band was
coming in like gangbusters. I am able to tune the 17 meter band.
A word to the wise. DON'T trust those old micas. If there going to be hard
to replace in the future, do it now, get it over with. Although the lower
bands seamed to function great, this cap ( C-67 ), being a bit leaky, was
affecting the performance of the receiver. It seamed that the higher the
frequency tuned, the less selective and sensitive it got.
PLEASE, Print this and stick it in your SP-600 manual. I promise, you will
be glad you did.
Regards,
Gary...WZ1M