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Old 3rd Aug 2020, 9:01 pm   #5
Scotorvm
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Join Date: Jul 2020
Location: Falkirk, Stirlingshire, UK.
Posts: 200
Default Re: Graves Vulcan II tuning help

Quote:
Originally Posted by Herald1360 View Post
Transformer windings? Is that the audio coupling TX or the tuning unit coils?

The circuit relies on dc continuity through the aerial coils and the wave change switch for the tuning condenser to resonate the circuit. The reaction feedback coil needs to be correctly phased in its coupling to the aerial coils for positive feedback to occur. All the connections need to be good and low resistance.

The grid capacitor and its parallel grid leak resistor are probably near enough to their values to be OK but it could be worth trying a couple of modern components instead to see if they help.
Hi Chris, yes the audio coupling TX.
Will check the reaction feedback coil and resistances, thanks for your help.

Cheers

Lee
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