[Hammarlund] SP-600 and drift--

[Arthur Delibert]

I had some random up-and-down drift on my SP-600 -- actually, not quite random, because it followed fluctuations of the local AC voltage supply.  Every time one of our electric heaters came on, the radio would change frequency.  I fixed it by adding a voltage regulator for the heaters.  Easily reversible.  Plans were in one of the editions of Fine Tuning's Proceedings about 20+ years ago.

Art Delibert
KB3FJO



> From: chuckochs at hotmail.com
> To: hammarlund at mailman.qth.net
> Date: Fri, 5 Jul 2013 11:39:10 -0400
> Subject: [Hammarlund] SP-600 and drift--
> 
> A couple of people have mentioned drift in the SP-600.Let me assure you that an SP-600 in proper operation condition has about zero drift. I have a late model one with the ceramic capacitors, and when I turn in on each night to listen to the chatter on 3.875 it is right where I left it the night before. Maybe a very slight tweak to zero beat, and nothing after that.My suspicions about those sets that drift are that they are probably suffering from capacitor / resistor disease, or from crappy replacement capacitors, or maybe the tuning capacitor has a bit too much wear, and "wanders" a bit as it is heated, or maybe the local oscillator tube needs changing.Given the spread of time and usage of these receivers, anything is possible. I feel fortunate to have such a nice radio!Chuck N1LNH 		 	   		  
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