[Hammarlund] SP-600-JX14

[Richard Knoppow]

     The hard part is getting to the IF in the box on the side of 
the turret and RF compartment. I don't think there is an easy way 
to access it. The second conversion oscillator and mixer are at 
the side of the RF box. You should be able to tell if they are 
working. If the receiver is dead on the upper bands check the 
switch at the back of the turret box. It switches the conversion. 
Its in a vulnerable spot, can be cracked if the bottom cover of 
the RF compartment is not removed carefully. I think I would 
check out this switch and its wiring before doing any disassembly.
    The switch is S-4 on the schematic. The only thing in the box 
on the side are two IF transformers. Could cause the problem. If 
you have a scope or good sensitive RF voltmeter check the output 
of the 6C4 IFO and see if you are getting signal to the second 
mixer.
    Its possible you have a bad 3.5mhz crystal.
    The military manual has complete mechanical drawings but I 
would be reluctant to take the RF assembly out.
    Its not too difficult to get the RF strip off the compartment 
but requires great care to avoid destroying the turret contacts. 
Also, I don't think the problem is there.

On 8/21/2020 11:42 AM, Brian Harris via Hammarlund wrote:
> I have the aforementioned receiver.  It works on the single conversion bands (<7.4 MHZ) and but on the double conversion bands it doesn't.  I know there are problems with the 3.5 MHz oscillator and second mixer.  Is there an easy way to get to the components under the associated RF chassis?  It looks like removal of the bandswitch turrent at minimum is required and that appears to be a formidable task.  Any comments appreciated..  Thank you.
>
> Brian Harris, WA5UEK cell 214-763-5977 email cosmophone at yahoo.com
>     

-- 
Richard Knoppow
1oldlens1 at ix.netcom.com
WB6KBL