[Hammarlund] SP-600 HFO Alignment

[Hy Chantz]

Hope all of you and yours are doing well during these challenging times.   

Question if I might...let's say one has access to an xtal calibrator for their SP-600, and/or a WWV or other off-the-air reference.

Other than an out-of-cabinet tweaking, what - if anything - is the common "Vernier" to use, to get the SP-600 dial readout exactly "on"? 

I don't readily see how one can easily align/move the dial scribe, there does not seem to be any commonly-installed  front-panel capacitor/trimmer to do this, and of course the tried-and-true fine-tuning of a Bandset to perfectly align the Bandspread as performed with other Hammarlunds, Hallis, etc. can't be done. 

( of course, an answer to the effect of "..the SP-600 has many strengths, dial readout is not chief among them..." is entirely satisfactory!)
 
Thanks and best 73s!

Hy  W2HY

----- Original Message -----
From: "Bill Cromwell" <wrcromwell at gmail.com>
To: hammarlund at mailman.qth.net
Sent: Tuesday, March 24, 2020 2:23:44 PM
Subject: Re: [Hammarlund] SP-600 HFO Alignment

Hi,

I took some radio/tv classes for a while (once upon a time) and they 
taught bending the *outer* rotor plates to get tracking in the AA5 AM 
broadcast band receivers. I have seen radios with intentionally bent 
plates and there was no satisfaction there. Don't do it.

73,

Bill  KU8H

On 3/24/20 11:11 AM, k2cby at optonline.net wrote:
> I would repeat in boldface underlined Never bend the plates of the tuning
> capacitor! It is undoable and a death sentence so far as proper alignment is
> concerned.
> 
> That said, there are several points to consider in trying to match the HFO
> frequency to the tuning dial.
> 
> 1.	On the frequencies below 7.4 MHz (the 3 lower bands) be sure that
> the IF is actually centered at 455 kHz, and on the higher bands be sure that
> the IF is aligned at 3,955 kHz and the crystal oscillator is putting out
> 3,500.00 kHz.
> 2.	Be sure there isn't some non-factory "improvement" hanging off the
> wire that runs from the plastic feed-through at the front of the RF strip to
> the VFO-Crystal oscillator switch. That wire leads directly to the HF
> oscillator, and any stray capacitance to ground will foul up the frequency
> calibration at the high end.
> 3.	Without touching the oscillator coils, use the proper size steel
> screwdriver to "exercise" the air variable capacitors of the oscillator
> section for each band. Especially if the boat anchor has been sitting
> untouched for a couple of decades, the capacitor shafts will stiffen and you
> will either bend or break a plastic alignment tool.
> 
>   
> 
> Miles B. Anderson, K2CBY
> 16 Round Pond Lane
> Sag Harbor, New York 11963-3821
> Phone: (631) 725-4400
> FAX: (631) 725-2223
> 
> e-mail: k2cby at optimum.net
> 
>   
> 
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-- 
bark less - wag more
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