[AMPS] A look underneath the Ugly amp. chassis.

[Jon Ogden]

on 11/3/99 09:59, measures at measures@vcnet.com wrote:

> During the Great Debate,
> there were many stern warnings from critics of "The Nearly Perfect
> Amplifier" (Jan., 1994 *QST*) -  to the effect that manufacturers don't
> use rheostats to control filament voltage (as per the article) because
> rheostats simply do not last in this application.    The rheostat still
> works after a dozen years of service.
> 
WHY?  Why would a rheostat stop doing what a rheostat is supposed to do???


> One should keep in mind that above its self-resonant frequency, a
> capacitor looks like an inductor.  For example, your typical 0.01uF
> disc-ceramic universal "bypass" capacitor looks like an inductor on 20m -
> 10m.  

I agree with your comment.  I am surprised though that the caps are that
poor.  I know even most "quality RF" caps (mica or otherwise) begin to look
really bad above 30 MHz, but I am surprised things look bad above 14 MHz.

73,

Jon
KE9NA


--
FAQ on WWW:               http://www.contesting.com/ampsfaq.html
Submissions:              amps@contesting.com
Administrative requests:  amps-REQUEST@contesting.com
Problems:                 owner-amps@contesting.com
Search:                   http://www.contesting.com/km9p/search.htm