[R-390] capacitor analysis

[John Saeger]

Helmut Usbek wrote:

> If you change the caps to 1.0uf you might end up with some motorboating at
> higher volume settings.  This happened to me when I did my audio mod.
Switched
> back to .1 uf and everything was back to OK.  The real bottleneck is the
> response of the output transformer. (among a couple of others)
> Try www.zorkler.com for an audio mod in the local part of the deck.
> regards,
> Helm.  WB2ADT

This is very interesting information.  It could explain some interesting
behavior I got with an old Transoceanic that I did *preemptive surgery* on.
It was one of the old ones with the waxy gooey capacitors and I was not too
careful about replacing capacitors with the same values.  I was fairly
cavalier about replacing capacitors with larger values which usually does
little harm with decoupling capacitors, but I think I did the same with the
audio coupling capacitors.  Although the radio worked when previously it did
not, there was a little motorboating from time to time.  Maybe I should go
back and have a look at what I did there.  Cool web site.

Thanks,  John