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ZL1ANM > OLDSET 16.07.09 01:15l 24 Lines 832 Bytes #999 (0) @ WW
BID : ZL1ANM-568
Read: GUEST
Subj: Re: Interest in vintage radios
Path: IZ3LSV<IK2XDE<DB0RES<ON0AR<GB7YKS<ZL2BAU<ZL1AB
Sent: 090715/2233Z @:ZL1AB.#06.NZL.OC #:31436 [AUCKLAND] FBB7.00i $:ZL1ANM-568
From: ZL1ANM@ZL1AB.#06.NZL.OC
To : OLDSET@WW
>Who remembers when the magnetising current for
>the speaker came from it being the smoothing choke in the radio's HT
>supply?
>Cheers ... Ray
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.
73 de Neil ZL1ANM
T4 1.5à24
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