[Amps] original thread: Peter Dahl transformers, remark about capacitors for switching supplies

[Vic K2VCO]

In a conventional 3.2 kV HV supply that I've built for my new amplifier, I bypassed each 
of the electrolytics with an 0.01 uf disc ceramic capacitor. My thought was that there 
will undoubtedly be RF leakage back to the power supply, and especially on 160 meters the 
regular bypassing of the HV line might not be adequate to keep RF out of the capacitors. 
RF would be another source of heat that could shorten their life.

It didn't occur to me that it might be possible to 'resonate' the capacitors at some RF 
frequency and make the problem worse! I'm interested in the answer to this, too.

On 4/1/2013 4:45 PM, Gene May wrote:
> 1.  I've read conflicting recommendations about adding a cap that presents a low impedance to RF, such as a .01 uF disc ceramic, in parallel with the MF filter electrolytics (in "switchers").  This would be to shunt out the RF components of power from the switching circuitry.  I've heard  some say "yes" to this cap, and others say "no" because it can form a resonant circuit at some RF and overheat or cause instability in the switching circuit, and others say it is a good idea but only if you use a cap that will handle the probably high RF currents.  What do you think about this practice -- paralleling the electrolytics with disc ceramics for the RF?  Would this advice vary depending on whether the ripple frequency was 120Hz or 20 KHz?

-- 
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco/