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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
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Default Philco 444 coupling wires "X" and "Y"

Hi,

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

Ewan
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Old 27th Jul 2021, 12:55 pm   #2
Cobaltblue
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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.

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Mike T
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Old 28th Jul 2021, 10:07 am   #3
turretslug
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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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