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Components and Circuits For discussions about component types, alternatives and availability, circuit configurations and modifications etc. Discussions here should be of a general nature and not about specific sets.

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Old 27th Jul 2021, 12:48 pm   #1
Ewan Penkey
Join Date: Aug 2020
Location: Chertsey, Surrey, UK.
Posts: 21
Default Philco 444 coupling wires "X" and "Y"


I'm servicing / repairing a Philco 444 for a friend, and hope someone here can shine some light on these wire couplings?
As per the description in the attached, I should expect to see a loop of wire around L3 and another wire somehow adjacent to, but not attached, to C22. Only I can't see either of these wires in this set.
Would anyone have a photo of these wires in situ?
I'm not familiar with this type of coupling, and want to get it right for my friend.

Many thanks

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Old 27th Jul 2021, 12:55 pm   #2
Cobaltblue's Avatar
Join Date: Dec 2010
Location: Exeter, Devon and Poole, Dorset UK.
Posts: 5,187
Default Re: Philco 444 coupling wires "X" and "Y"

Gimick capacitor Y if I remember correcly is on the tuning gang.

It consists of a piece of insulated wire soldered to one gang at one end and wraped with no physical connection insultion intact around the tag of the other gang of the tuning capacitor.


Mike T
Don't care if it was a bargain why's it in my kitchen
Mike T BVWS member.
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Old 28th Jul 2021, 10:07 am   #3
Join Date: Nov 2011
Location: Surrey, UK.
Posts: 3,846
Default Re: Philco 444 coupling wires "X" and "Y"

As an aside, it's fascinating that simple but effective circuit elements like these are actually present, especially in what was presented as a basic low-cost receiver, in order to squeeze optimum performance out of it. I assume that X helped to even up coupling effectiveness across the band and that Y neutralised space-charge coupling within the heptode, optimising noise performance and minimising "pulling". Components of virtually zero cost but with sound technical justification for their presence, the essence of good production engineering.
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