[ARC5] Back to basics: Capacitor breakdown voltages

[Dennis DuVall]

True, but the capacitors at issue here are upstream from that point.  The radio here is a BC-375 and the apparent function of the 
three-section HV capacitor under discussion was to suppress dynamotor hash.

Three section unit here, one section bypasses the HV feed to the RF circuits, a second section bypasses the HV feed to the modulation 
transformer and a third section bypasses the HV feed to the speech amplifier and is connected at the low tension end end of a 
voltage dropping resistor string.   The failed section here was the one bypassing the HV feed to the RF section.  Jim reports that 
the radio appears to function normally with this section cut out of the circuit (no surprise) and the set is likely to work OK with 
the other two capacitor sections removed as well considering the fact that he is using an AC, well filtered high voltage power supply 
with the radio.  Back on a dynamotor, results TBD……

Dennis D.  W7QHO
Glendale, CA

*******************

> On Jan 24, 2016, at 11:33 PM, spr at earthlink.net wrote:
> 
> From: Dennis Monticelli 
> Sent: Jan 24, 2016 11:28 PM 
> To: "WA5CAB at cs.com <mailto:WA5CAB at cs.com>" 
> Cc: ARC-5 Maillist 
> Subject: Re: [ARC5] Back to basics: Capacitor breakdown voltages 
> 
> Let's not forget that the voltage at the plate of the final can exceed twice the HV rail under certain load load conditions (i.e. SWR).  This is true whether the rail is steady (CW) or time varying (AM peaks).  This is one the big reasons why arcing sometimes occurs in tubes, var caps, and switches. 
> 
> Dennis AE6C

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