wrote:
mike maghakian wrote:

this seems like a pretty good article on upgrading caps and resistors
in
audio equipment, but I am not sure how far one wants to go in a SW
receiver
!

http://www.bext.com/replace.htm
--------------------------------
Based on what Ihave been finding out in the last month pretty
much correct. I hope this line is a typo:
"For low voltage work, the 50V ECQ-P series from Panasonic
(available through Digi-Key) is excellent, but they only go up to
0.47pF" 0.47pF?? I hope that is 0.47uF.

Eletroclytics sound bad.
They sound wose when improperly biased.
I could hear no significant difference between the normal
unipolar one and the bi-polar units. At the very least shunt
them with 1uF polys.

And metalfilm resistors can be much quiter. I would love to
have the time, and money, to change all th carbon films in
one of my R2000s and compare the result to the other.

Worthwhile for SW? Clearly to some degree. I have found
the distortion caused by junky caps to be very significant.
The typical diode detector is clearly the worst, followed by
the alltoo common **** poor power IC. But caps can cause
the loss of of diffrence between "cofee" and "copy". In
inguistic terms it blurs the "frictive" and "plosive" sounds.
"Terry" and "Jerry" are other examples. Fro a clean, clear
and "strong" signal the diffrence is minimul. But for very weak,
sub S1 or with QRN/QRM it can make the difference beween
undersanding and just telling a voice is there. For non
native language, IE for me Spanish, I had noticed that I
required a much better signal to understand then with
English.

Grabbing the audio before it is so mungled, for the R2000
the Rec out is a good choice, using a good audio amp,
a small tub or MOSFET may be ideal, and using good
speakers or earphones can help. I decided that it was
well worth the considerable effort to use a better detector.
And seperate audio chain.

Distortion is just noise and degrades the audio in strange
and maybe unpredicatable ways. In my outboard ID strip,
synch and product detector, I am using metal film resistors
for all signal pathways. Overkilll? I don't know. A month ago
I would have, and did, scoff at the idea that the "fairly minor"
distrotions and colarations causd by caps power ICs and
diode detector could have ANY real effect. After all by the time
a radio wave makes it to my reciver from around the world,
with multiple hopes through a nasty ionosphere that in itself
does a good job at bluring audio, what is a little more here
going to hurt? Sadly a lot. I now have a higher "fi" post radio
audio chain then our main entertainment system. Of course
when listen to CSN&Y I am not dealing with weak signals
at the lower limits of "listenability".

Terry

An excellent post Terry, solid information on an interesting subject.
Well done.

bill
KC9CS