[Hammarlund] PSK-31 on an SP-600

[Carl]

----- Original Message ----- 
From: "Richard Knoppow" <1oldlens1 at ix.netcom.com>
To: "Les Locklear" <leslocklear at cableone.net>; <k2cby at optonline.net>; 
<hammarlund at mailman.qth.net>
Sent: Sunday, August 07, 2011 10:49 PM
Subject: Re: [Hammarlund] PSK-31 on an SP-600


>
> ----- Original Message ----- 
> From: "Les Locklear" <leslocklear at cableone.net>
> To: <k2cby at optonline.net>; <hammarlund at mailman.qth.net>
> Sent: Sunday, August 07, 2011 4:34 PM
> Subject: Re: [Hammarlund] PSK-31 on an SP-600
>
>
>>I have a modified John R. Leary that has a product detector
>>and listen to ssb nets for hours on end with a couple of
>>light touches on the tuning knob.
>>
>> Ain't technology great? All those bells and whistles and
>> 1950's stuff still keeps pace!
>>
>> Way to go Miles.
>>
>> Les Locklear
>> Gulfport, Ms.
>> DX'ing Since '57
>>
>     The SP-600 was designed to be a very stable receiver. I
> suspect the reason many complain that they are not is
> because their receivers have problems. I think a lot of
> SP-600's work but are sick. For one thing apparently the
> stators of the tuning capacitors drift with time. They
> should be exactly centered both between the rotor blades and
> vertically. They are clamped in place so I suspect can move
> around just a little with time. This will also affect the
> dial calibration, which should be quite good, and the RF
> tracking, which should also be right on. I've found a couple
> of receivers where someone has bent the plates of the
> capacitors to try to compensate for the effect of the
> stators being out of place. Once bent they can never be
> gotten quite straight again so it should NEVER be done.
> Aligning the stators requires removing the capacitor from
> the tuning unit, not too difficult but a lot of work.
>     Some of these receivers are also very microphonic. I
> think that may be where the original, rather large, paper
> caps were replaced with disc ceramics. The ceramic caps can
> vibrate. I have not yet tried a cure I think will work,
> namely fixing them in place with blobs of silicon rubber.
> Its easily removable. I have a couple of receivers on the
> back burner, may take a while to get to them but will report
> on what I find when I do them.
>     Another problem is that there is no regulation for the
> filaments of the oscillator. When line voltage changes it
> can cause quite a bit of drift. My solution was just to put
> the RX on a Sola transformer. If you have reasonably stable
> line voltage this will not be a problem
>
> --
> Richard Knoppow
> Los Angeles
> WB6KBL
> dickburk at ix.netcom.com
>

The SP-600 drifted since new which is why they had the X designation.
I even doubt a R-390A is standalone PSK-31 capable without some work.

Carl
KM1H