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
On Mon, Dec 17, 2012 at 11:36 AM, Chris Wilson <chris@chriswilson.tv> wrote:
>
>
> 17/12/2012 17:34
>
> Having built a big 5kV 1.8 amp supply that seems to work safely and
> well, I want to build a lesser one for a single GS35B 2 meter amp. I
> have a suitable transformer with a good range of taps to be able to
> vary the output voltage through a fair range, and have acquired a 4
> Henry 2 Ampere choke (not a swinging choke, a "normal" one). I am
> wondering if I should attempt to use it rather than a capacitive input
> filter? What design criteria can I follow to check if it's suitable,
> and if so, to choose a suitable cap and bleeders to go with this? It's
> from a dismantled and parted out Hirschmann 3500V DC supply. My supply
> will be run off single phase, 50Hz UK 240 volt mains. Thanks.
>
> --
> Best Regards,
> Chris Wilson.
> mailto: chris@chriswilson.tv
>
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