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G0TEZ > OLDSET 18.07.09 15:30l 26 Lines 855 Bytes #999 (0) @ WW
BID : FA0078G0TEZ
Read: GUEST
Subj: Re: Interest in vintage radios
Path: IZ3LSV<IK2XDE<F8KFY<ON0AR<GB7YKS<GB7SYP<GB7FCR
Sent: 090718/1246Z @:GB7FCR.#16.GBR.EU #:29742 [Blackpool] FBB-7.03a $:FA0078G0
From: G0TEZ@GB7FCR.#16.GBR.EU
To : OLDSET@WW
You mean you never found a hum bucking coil,Neil.
....don't know why we always found that amusing :-)
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I remember pulling old radios to pieces for spare parts in the mid-60's
when I was a teenager, and yes, the early models did have a winding on
the loudspeaker through which the B+ was fed. It served a dual purpose
as you say: B+ filter choke, and magnetising current for the speaker's
iron core. Hum would become a problem if the winding's leads or speaker
audio leads happened to become reversed by a careless serviceman, since
it was intended that the hum induced in the magnet core would negate
any hum present in the audio output.
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73 from Ian, G0TEZ...
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