[Amps] How much C in PS is too much ?

[Jim Thomson]

Date: Mon, 22 Mar 2010 09:51:52 -0700
From: "Bill, W6WRT" <dezrat1242 at yahoo.com>
Subject: Re: [Amps] how much C in PS is too much?

ORIGINAL MESSAGE:

On Sun, 21 Mar 2010 12:11:21 -0800, "Zeitler, Lane LT, FST-1"
<zeitlel at cpr3.navy.mil> wrote:

>at more or less
>1250uF total capacitance. Is this too much?.

REPLY:

>From a good engineering point of view, you should use just enough
capacitance so that adding more makes no audible difference at the
receiving end. This is a subjective judgment of course, but for a
typical 3 kV, 850 mA supply, that is about 50 uF. Some commercial maps
(Command) use as little as 35 uF so the value is not really critical,
obviously. But I wouldn't stray too far from those values. 

73, Bill W6WRT

##  after actually doing it now for 3 yrs... I'd say you want a MAX of 1% ripple.
To pull that off on a typ 3 kv @ 800 ma supply, requires 8 x 600 uf caps..or 
75 uf.   Now if the supply is a FWDoubler, I'd use even more.  The caps in 
any doubler have to hold their charge twice as long as a FWB. 

##  I wouldn't be holding Command or anybody else up as any kind of 
'standard of engineering excellence.'  If these ham amps  were built right,
they would all have individual, adjustable bias  for each tube, plus mating
metering, real bandswitch's and real tank coils, and plate xfmrs... and maybe 
toss in a real tube..... and not something with a floozy 4 watt delicate grid.

Jim   VE7RF