[R-390] Paper Capacitor Replacement II

[Perry Sandeen]

List,

Wrote: As an aside, I did my R-390A with Orange Drops, and then discovered the Illinois Capacitor axial-lead caps at www.tubesandmore.com.  I've recapped four or five pieces of gear with them and have had great success.  That's my first choice for axial-lead caps to replace the old paper caps; others choose differently, of course.

While any modern film capacitor will be decades better than the film caps that they replace. It is still the wrong choice.  No personal offense to anyone, but this is a case of the blind following the blind.

Here’s why.  (IIRC, this has been brought up before on the list.)  When our BA’s were designed, good ceramic bypass capacitors had not been developed, so wax paper and foil capacitors were used.

As a result and urban myth of using OD’s has developed.  OD’s and their film equivalents are fine for AUDIO only.

Ceramic bypass capacitors have a much lower ESR at RF for any given capacitance.  It is well documented in many amateur and professional electronic books. 

Additionally, they are far less expensive and much smaller.

There are those on the list who vehemently disagree with me.  But where is their documented scientific proof?  All I remember hearing were opinions.  Well opinions are like eyeballs.  Everyone has one, two, or three of them.

As further proof, for about the last 40 years or so ceramic bypass capacitors have been used exclusively for RF bypass by commercial equipment manufacturers. 

Yes, I’m a bit testy about the subject but that is a reaction to those who just keep re-posting over and over their favorite urban legends while ignoring the facts.

I don’t care if these individuals recap their radios with whatever they fancy.  That is their choice.

Ceramic are for RF ONLY and film capacitors are for AUDIO ONLY.

Deviation results in much lower than-can-be-obtained performance on any given BA on any given day.

Regards,

Perrier