----- Original Message -----
From: Vic Rosenthal <rakefet@rakefet.com>
To: Steve Lawrence <smlx@earthlink.net>
Cc: <amps@contesting.com>
Sent: 16 November 2002 17:11
Subject: Re: [Amps] LP filter effects
> Steve Lawrence wrote:
> >
> > I have an old Drake 1KW LPF in line running 1500w output from an Alpha
87A
> > to a TH7DX. It's worked fine for several years. I've pulled the LPF out
of
> > the line. At 28000 with 1500W out, the reflected power dropped from 200
to
> > 100 watts. There is also an improvement on 20 and 15.
> >
> > Comments appreciated.
>
> The extra 100 watts of reflected power could be harmonic energy above the
filter
> cutoff. In other words, the filter is doing its job. Or some components
have
> changed value and the filter's characteristic impedance isn't 50 ohms any
more.
If we are looking at 100W of harmonic energy in 1500W output power, that's
only 12dB down. I'd expect the amp to be a lot cleaner than that.
Steve
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