[Hallicrafters] CW Pitch on SX-71

[Julian Bunn]

Hi Paul,

The special knob attaches to the threaded shaft. The knob has a small
boss on it that prevents the knob being turned more than one revolution.
The knobs are difficult to find, but Gary may have one. I have some
closeup photos of the knob on my SX71 page:

http://pcbunn.cacr.caltech.edu/jjb/hallicrafters/SX71/sx71.htm

in particular:
http://pcbunn.cacr.caltech.edu/jjb/hallicrafters/SX71/knob_replacement.jpg

Julian

Paul Adolph wrote:
> Hi, I have a Hallicrafters SX-71 that I am re-capping.  While I am at it 
> I want to look at the CW-Pitch control as there was never a knob for this.
> What I see is a long slotted threaded shaft that runs from the front 
> where the knob should be through the coil that is the bfo coil (L3 on 
> the schematic).
> Having never seen this the way it was designed I was wondering if 
> varying the threaded shaft in or out is the way this was designed and I 
> simply need to get the proper knob, or if someone modified it to accept 
> the threaded shaft.  Is this the way is should work?
> Anything else I may need to look out for while I am in this receiver 
> would be appreciated as well.  The radio does receive now but the caps 
> are original and I feel may be weakened based on how it was stored 
> before I received it. 
>  
> Thank You,
> Paul
>  
> 
> 
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