> 4 H is a bit low; 8 would be better. Choke input filters are good for
> power supply loads that are fairly constant, i.e. modes like AM, FM,
> and RTTY. Take a look at the designs used in earlier amps like the
> Heathkit HA-10 as something to work off of, also the power supply
> sections of 1 KW vacuum tube AM broadcast rigs. Don't forget old
> handbooks, West Coast and ARRL from the '40s and '50s. if you are in
> the UK perhaps RSGB has old handbooks with design criteria. You could
> start with an 8 uF oil cap. Let's assume you are going with 3.5 KV.
> Look for a cap rated for over 4; 4.5 KV or more is a good idea.
> Follow that with the choke and another oil cap like the first one at
> the input. Don't fool around with electrolytics that will need to be
> replaced some day--this is a filter that will last as long as you do.
> Use the ratings of the choke as your guide. Make sure the v. rating
> of the caps is working volts DC. Stay away from energy discharge
> caps--a genuine filter cap will be bigger with sizable insulators on
> the contact lugs.
> 73
> Rob
> K5UJ
19/12/2012 14:03
Thanks for the reply Rob. Is there a way to check the inductance of
another choke I have? The other one is bigger, and is from a 3 phase
supply for a Henry RF Generator. It gave just under 5kV at 1.5 amps.
Henry use the same part number in both the 3 and single phase versions
of the HV supply, but the single phase version uses 2 off 0.1uF
resonating capacitors, and a 4uF filter cap, with fairly low value
bleeder resistors. I believe these are to keep off load voltage in
check? The Henry schematics show both supplies using the same part
number of choke, but the 3 phase uses no resonance caps. The
schematics don't give the inductance though.
I believe an HV choke needs measuring for inductance with DC on it,
for the purposes of use as a resonant choke, and making it resonant at
twice the mains frequency (100Hz in this case, after a full wave
bridge).
--
Best Regards,
Chris Wilson.
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