[Amps] Ceramic capacitor ratings

[Robert Bonner]

Boy exactly Peter...  I've always thought the same thing.  Pop the top off
an amplifier rated at such and such and go, whoa, these guys are dreaming.

Every amplifier I've built after the first few were built to make POWER.
All components have been CCS or larger.  I've found the amp will define the
weak links with time... I don't have the time to be fixing.

It's a different story when producing a product for sale.  There they want
to shave every cent out of the product they can.  My personal philosophy has
always been to spend a buck to save a buck.

There was a long standing joke back in the 60's regarding MAGNAVOX TV Sets.
You were meant to understand the engineers would build a fantastic TV set...
The Bean counters would then start clipping parts out of the TV until it
stopped working and then solder that part back in.  That's the set they'd
produce...

All through the 60's and 70's Magnavox TV's were nothing but TVI receivers.
They were popular because they were cheap...  A few of them in my near
neighborhood sure made my life miserable growing up.

BOB DD

-----Original Message-----
From: amps-bounces at contesting.com [mailto:amps-bounces at contesting.com] On
Behalf Of Peter Chadwick
Sent: Sunday, April 15, 2007 12:44 AM
To: amps at contesting.com
Subject: Re: [Amps] Ceramic capacitor ratings

Manfred said:
>By the way, we can get even more peace of mind if we consider that an 
amplifier in ham use will run in ICAS, and typically in SSB, with an 
average much below the peak. So it turns out that those 100pF caps in 
practice will just be loafing along!<
I would have supported this view until recently, when I started a rebuild of
a 45 year old amplifier where the capacitors were rated on that basis. There
I found definite signs of overheating, with presumably some loss of
metallisation, as the measured capacity was only 50% of what it should have
been in one case. So although the concept is true, I'm not too sure about
long term reliability. Of course, you could question quite what you want in
terms of life from an amplifier!! It's the sort of thing you can get
probably get away with if you're 60 years old, but you may not want to if
you're only 20.
73
Peter G3RZP
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