[Hallicrafters] SX-62 tuning

[howard holden]

I have an SX-62 that I recently restrung part of. There are two strings 
- one from tuning knob shaft to the capacitor, one from the capacitor to 
the dial. I restrung the one from the knob to the cap. It's important to 
make sure you have the correct number of turns around the tuning knob 
shaft, otherwise there will be slippage. Of course also make sure there 
is adequate tension on the string. It's also important to make sure the 
grooves on the capacitor pulley and on the tuning knob shaft are clean 
and smooth so the dial cord can move sideways in the groove as the 
capacitor is tuned, otherwise you will get the hangup. First-hand 
experience.

73, Howie WB2AWQ

On 11/2/2016 11:09 AM, Richard Knoppow wrote:
>     I think is necessary to isolate the problem. That may require 
> removing the dial string from the tuning cap so you can turn the cap 
> by itself. If the binding is there you can look for the cause. I think 
> you said you had lubricated its bearings. Many air variables have some 
> sort of wiper to connect the rotor, worth looking at. Also, check the 
> centering of the rotors in the stator. If its not perfectly centered 
> it means the bearing loading is wrong. It will also affect the tuning 
> law.
>     If the cap is OK having the dial string off will also allow 
> checking everything it runs over in its path. I have not looked at the 
> handbook but think the dial stringing is not trivial in these receivers.
>     BTW, I first saw an SX-62 at Yale Radio, a major parts supplier 
> here in L.A. when I was a kid. I wanted one. Of course never had one. 
> I see them every so often at the TRW swap meet usually in pretty awful 
> condition. They are supposed to be painful to work on.
>
> On 11/2/2016 9:11 AM, Waldo Magnuson wrote:
>>   Thanks Richard for responding.  I've very carefully checked the 
>> tuning capacitors and I saw no shorts or touching or binding.  What I 
>> did find is that when I tune across the band the tuning knob capstan 
>> string crosses on itself and finally binds up. The string all looks 
>> okay so it is not obvious what the cure is.
>> Skip W7WGM
>> --------------------
>>
>>   Check to see that the extra force is from the tuning cap. If it is
>> the most likely cause is something stuck between the plates or one or
>> more plates bent enough to be rubbing. If that's happening the cap will
>> short and the set will go dead where the plates touch.
>>
>>> On 10/31/2016 4:47 PM, Waldo Magnuson wrote:
>>> Hi All,
>>>   I'm getting back to my SX-62 and tuning it up to display in my front
>>> room but ran into a problem. The tuning capacitor seems to hang up half
>>> way from full mesh to open mesh.  I can physically move it but with a
>>> bit of force. The cord slips at that point.  Has anyone experienced the
>>> same? I have oiled all the small pulleys and other parts (end of the
>>> capacitor) and I don't see what the problem is.  Thanks for any help.
>>> Skip Magnuson W7WGM
>>> Spokane, WA
>>
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>