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[AMPS] Re: HV Power Supply questions

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Subject: [AMPS] Re: HV Power Supply questions
From: (Rich Measures)
Date: Fri, 19 Feb 1999 20:20:38 -0800

>Hi Rich
>Thanks for the info on the capacitors. 

ur welcome.

>I've decided to cc a copy of this
>exchange to the amps list to let everyone hang an ear. In terms of mounting
>these caps like you said I'm not planning to use metal clamps. What I'm
>looking to do is use 2 pieces of plexiglass. The top piece will be machined
>out to accomodate the capacitors with the caps being secured to the buttom
>with silicone. Then mounting the bottom pieces to the chassis view
>conventional hardware.
What is the purpose of the machined piece of plexiglass?

>Now for a couple of more questions.
>1) On the return side of the HV line. Over the years I've seen many designs
>that tie the B- straight to the chassis. Others have allowed it to float by
>connecting it to a low value high wattage resistor which is then connected
>to the chassis. I think it's purpose was for metering but I don't remember.
>What's your take on this? Is this necessary or a good idea?

In order to measure the grid current on a tube with a grid-grounding 
collet, the grid current meter shunt resistor must be the only current 
path between the chassis and the neg hv.  Glitch diodes should be 
connected across this resistor.  
>2) In the rectifier circuitry, I'm using a string of 1N5408s, years ago
>convention required equalizing resistors and transient suppression caps
>across each diode. I understand that equalizing resistors do more harm than

Yea, verily.  .  Amateur radio's old wives' tales die an exceedingly slow 

> and thus not employed. But I'm not clear about transient suppression
>caps across each diode. 

Not needed in transformer operated supplies. 

>Are these passe in the age of Transient Suppressors
>used in the Primary of the transformer?
With a C-filter,  +/- transients simply get rectified and stored in the 
filter cap.  Thus, no mov  is needed in the transformer primary.  With a 
resonant-choke filter, I would use a mov in the primary.  
-  later, Bob


R. L. Measures, 805-386-3734, AG6K,  

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