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 Post subject: Checking oscillators, fixing tuning screws
PostPosted: Dec Tue 04, 2018 3:49 pm 
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Joined: Jan Mon 28, 2013 9:35 pm
Posts: 1486
Location: Santa Rosa, CA
Just posted part of this in the 'communications' group but
might be worth repeating here.

When troubleshooting or adjusting tube oscillator circuits,
a good way to see what its doing without probing
(which will change the characteristics of the circuit) is
to wind a few turns of wire around the tube and connect
that to a 'scope.

Quite often the part of the slot in slug tuned coil tuning screws
are broken off. Soldering a 6-32 nut (which is what most seem to be)
to the end of the screw makes tuning easy again.
Steve

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 Post subject: Re: Checking oscillators, fixing tuning screws
PostPosted: Dec Tue 04, 2018 6:41 pm 
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Joined: Sep Tue 30, 2014 6:08 am
Posts: 4897
Location: Norfolk, VA
zarco wrote:

Quite often the part of the slot in slug tuned coil tuning screws
are broken off. Soldering a 6-32 nut (which is what most seem to be)
to the end of the screw makes tuning easy again.
Steve


Like this?

Attachment:
broke -fix is nut.jpg
broke -fix is nut.jpg [ 32.15 KiB | Viewed 976 times ]

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 Post subject: Re: Checking oscillators, fixing tuning screws
PostPosted: Dec Thu 06, 2018 3:35 am 
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Joined: Jan Mon 28, 2013 9:35 pm
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Location: Santa Rosa, CA
Thats the idea. Thanks for posting a pic Brian.
Steve

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 Post subject: Re: Checking oscillators, fixing tuning screws
PostPosted: Dec Sun 09, 2018 8:02 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 3425
Location: Olympia WA USA
Great idea, but please keep in mind that a ferrous nut may change the tuning properties a lot, as can a non ferrous brass nut added onto the shaft.

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 Post subject: Re: Checking oscillators, fixing tuning screws
PostPosted: Dec Wed 12, 2018 10:24 pm 
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Joined: Oct Thu 18, 2007 11:34 am
Posts: 4177
Location: Port Orchard, Wa 98366
Well you can always get nylon or plastic nuts and epoxy those. shouldn't influence inductance properties.

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