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G6XGF > OLDSET 25.07.09 21:17l 19 Lines 640 Bytes #999 (0) @ WW
BID : 1B0379G6XGF
Read: GUEST
Subj: Hum Bucking
Path: IZ3LSV<IK2XDE<DB0RES<DK0WUE<7M3TJZ<ZL2BAU<GB7PZT<GB7MAX<GB7DBY
Sent: 090725/1552Z @:GB7DBY.#23.GBR.EU #:63105 [City of Derby] FBB7.00g25
From: G6XGF@GB7DBY.#23.GBR.EU
To : OLDSET@WW
Hi all interested in this subject.
When a mains energised speaker got it's current from rectified AC it was
found that hum could arise from ripple, particularly if the coil was also
utilised for smoothing.
The problem could be overcome with a Hum Bucking coil. This was tightly
coupled to the speaker energising coil and connected in series with the
speech coil. The object of this configuration was to intruduce a ripple
voltage which was out of phase with the directly introduced ripple
voltage, and, if the number of turns were correct the ripple was cancelled
out.
73 de Dave, G6XGF.
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