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KB2VXA > OLDSET 21.07.09 12:19l 29 Lines 1082 Bytes #999 (0) @ WW
BID : 309_VK2TV
Read: GUEST
Subj: Re: ZL1ANM > hum bucking
Path: IZ3LSV<IK2XDE<F8KFY<F1ZNR<F4BWT<ON0BEL<CX2SA<N9PMO<KB2FAF<KD4YAL<
VK2TV
Sent: 090721/1012Z @:VK2TV.#MNC.NSW.AUS.OC #:309 [Kempsey, QF68JX] $:309_VK2TV
From: KB2VXA@VK2TV.#MNC.NSW.AUS.OC
To : OLDSET@WW
Hi Neil and all,
The hum bucking coil was a winding on the speaker electromagnet that was
fed from the filament line, exactly how I don't remember. "In an
unrelated incident" I had a hi-fi amp with a wire wound pot across a
floating heater line, that is to say neither side was grounded, rather
the wiper was.
Er, make that "heater line" in the first sentence, it just crossed my
mind that earlier sets had tubes/valves with directly heated filaments
that operated from an A battery and permanent magnet speakers or
headphones. When electricity came to town battery eliminators that often
dropped into compartments inside the radio sets became popular thus
saving people from lugging heavy batteries out to the old jalopy and
hauling them to the town garage for charging.
I vaguely remember a thread about "farm chargers" or something like that,
maybe someone could elaborate.
73 de Warren
Station powered by JCP&L atomic energy, operator powered by natural gas.
Message timed by NIST: 10:12 on 2009-Jul-21 GMT
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