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IK0VNQ > OLDSET 22.07.09 14:49l 51 Lines 1875 Bytes #999 (999) @ WW
BID : M7JIK2XDE03R
Read: GUEST
Subj: Re^2: KB2VXA > hum bucking
Path: IZ3LSV<IK2XDE
Sent: 090722/1336z @:IK2XDE.ILOM.ITA.EU [Italy] obcm1.07b3 LT:999
From: IK0VNQ @ IK2XDE.ILOM.ITA.EU (Filippo)
To: OLDSET @ WW
X-Info: Sent with login password
From: KB2VXA@VK2TV.#MNC.NSW.AUS.OC
To : OLDSET@WW
>Hi Filippo and all,
>
>Sorry OM, you have your coils confused. You're talking about the
>energizing winding which carried the DC + AC ripple power supply current,
>the topic has already been covered. Now we're talking about a separate
>winding that carried AC which induced a magnetic field of it's own having
>equal amplitude and opposite phase of that induced by the main winding,
>"bucking" it out.
>
>If you remember how to connect transformer windings to obtain a voltage
>unavailable from one alone you're familiar with additive and subtractive
>voltages depending on phase. When windings are connected out of phase
>they are said to buck each other, a portion of the voltage is bucked out.
>The very same principle was used in the design of the speaker, without
>the second coil the ripple current would produce a nasty hum, AC current
>was used to buck it out hence the name hum bucking coil.
>
>73 de Warren
>
>Station powered by JCP&L atomic energy, operator powered by natural gas.
>
>Message timed by NIST: 20:36 on 2009-Jul-21 GMT
>
.....................................................
Hi Warren and all,
thank you Warren, you are perfectly right, I was confused on the topic.
Even though I started to play with radio sets in the Jurassic Era (HI), let say
around 1950, I don't remember if there was any tecnique you mention to
suppress hum in sets built at that time. Maybe it was applied in sets built
before WW II ? I dunno.
What I remember is that those receivers with wooden cabinet and big speakers
sounded great, no hum, no nothing!
Thanks for the technical informations anyway.
Best regards
73 de Filippo
IK0VNQ @ IK2XDE
>>> GREETINGS FROM THE ROMAN CASTLES, LAND OF WINES <<<
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