[Milsurplus] question re filter caps

[J. Forster]

David Ross wrote:

> folks -
>
>   I am in the process of resurrecting an old aircraft radio & it's
> dynaverter (solid-state dynamotor).  The dynaverter is electrically very
> noisy, and I suspect that it's filter cap has dried out and is no longer
> doing it's job.
>
>   The dynaverter's main filter cap appears to be a single 3uF wet-slug
> tantalum.  What sort of cap should I replace it with?

A 3uF wet-slug tantalum? (It'd have a low ESR) I would check the capacitor
before condeming it. What type tantalum is it?

> The dynaverter puts out 270VDC @ ~70mA, switches at ~2KCs, and space is
> somewhat limited.
>
>   Would it be useful to build in a pi-filter setup with a pair of caps and a
> small choke?

I'd look at your installation and wiring before assuming the original designers
were idiots. Are your DC input wires twisted and/or shielded?

-John

> thanks
> Dave Ross    N7EPI    ross@hypertools.com