[AMPS] SB-200 & 10MHz++

Peter Chadwick Peter.Chadwick@zarlink.com
Mon, 17 Dec 2001 14:35:02 -0000


Alex says;

>Why is it that I hear somewhere between your lines:
>"Why did I not think about it?"
 
Sorry Alex, don't quite follow you. Are you suggesting that I'm wondering why I
didn't think about getting rid of the tuner and going to a pi tank instead of a
Pi-L?

If that is what you are suggesting, I would have thought the answer was obvious
-

Because you won't get the rejection of harmonics that is required to meet the
FCC requirements from a Class AB amplifier followed by a pi tank on its own.

With the combination of a pi tank and a tuner, you may do so, but with a vast
range of possible load impedances, and thus working Q in the tuner, it can't be
guaranteed. Anyway, the way the FCC rules are written, the amplifier itself
without a tuner needs to meet the 40dB requirements.

If you could, why would the manufacturers all use Pi-L networks?

Back in the 'good ole days' 40 years ago, on 160, when we had a 10 watt DC input
limit here, a many rigs did just as you suggest. A lot of people on 160m AM
could be well heard outside the 80m amateur band, radiating nicely on their
second harmonic......

73

Peter G3RZP

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