[Amps] Henry 2KD-5 120 Hz Hum

[Leigh S. Jones, KR6X]

Henry amplifiers use resonated chokes to achieve their normal high 
attenuation of HV power supply hum rejection.   If the resonating capacitor 
has broken down, or if there has been a short across the turns of the 
inductor, the hum level would increase with a few attendant symptoms.  The 
symptoms might include an increase in the unloaded plate voltage and reduced 
stability of the HV.

----- Original Message ----- 
From: "hamguy2" <hamguy2 at fuse.net>
To: <amps at contesting.com>
Sent: Sunday, August 06, 2006 11:56 AM
Subject: [Amps] Henry 2KD-5 120 Hz Hum


>I have a Henry 2KD-5 that I am using on AM running 300 watts.
> There is a low level but noticeable 120 Hz hum on the unmodulated
> carrier in CW mode.  The hum is super imposed on the AM signal
> amplitude.  Local stations can hear the hum.  I have tried two
> exciters and they are not the source.  I have recapped the filter
> capacitors to 250 mF without change in symptoms.
>
> Is there something else to check or do I just live with the hum?
>
> ----------------------
> Ron Schuster N9RC
> ---------------------- 
>
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