Help:Hammerlund SP-600
 

I'm having a hard time resolving a problem on an SP-600,
JX-26 I'm restoring. Hopefully there's someone out there
that can help.

On the 3.45-7.4 MC band (only), received signals are somewhat
distorted. Normally, when tuning in a CW signal with the BFO on,
you'd expect an undistorted tone as you tune. On my radio, it'll
sound more like a growl. Signal strength doesn't seem to matter.

I just finished a complete re-capping of this radio. Anyone need
about 60 leaky black beauty caps??? The problem existed before
I re-capped the radio. I was hoping new caps would solve the problem.
It didn't.

As I mentioned earlier, all other bands are fine. Sensitivity and
selectivity is good.

I have removed the ceramic tuning sections, and didn't find any
cold solder joints or flakey contacts. All tubes have been tested
and are OK. Power supply voltages are normal.

Steve

Help:Hammerlund SP-600
 

Since this problem is showing up on one band only,I would connect a
scope to the switchable oscillator and check the stability of the osc
signal on this band. It could be trashy or FM ing..Thats about the
only thing that would show up on one band only..Other places to look
would be the band switch,defective osc circuit ,such as damaged
parts,bad trimmer caps,coil form etc..GL W4PQW
Steve wrote:
I'm having a hard time resolving a problem on an SP-600,
JX-26 I'm restoring. Hopefully there's someone out there
that can help.

On the 3.45-7.4 MC band (only), received signals are somewhat
distorted. Normally, when tuning in a CW signal with the BFO on,
you'd expect an undistorted tone as you tune. On my radio, it'll
sound more like a growl. Signal strength doesn't seem to matter.

I just finished a complete re-capping of this radio. Anyone need
about 60 leaky black beauty caps??? The problem existed before
I re-capped the radio. I was hoping new caps would solve the problem.
It didn't.

As I mentioned earlier, all other bands are fine. Sensitivity and
selectivity is good.

I have removed the ceramic tuning sections, and didn't find any
cold solder joints or flakey contacts. All tubes have been tested
and are OK. Power supply voltages are normal.

Steve

Help:Hammerlund SP-600
 

Steve wrote:
On the 3.45-7.4 MC band (only), received signals are somewhat
distorted. Normally, when tuning in a CW signal with the BFO on,
you'd expect an undistorted tone as you tune. On my radio, it'll
sound more like a growl. Signal strength doesn't seem to matter.

For some reason some SPs have too much LO injection on one band.
Try lowering the 105 Reg with a pot and see if that does it...
73 W7ZFB