With that being said, a T network works well with one adjustment on the
input. I use one on my 6 meter amp. Remember, you still have that amplifier
tube that is going to generate its own distortion. So all the filtering in
the world will not work before the final amp unless you filter just before
the antenna. You generally have no control of phase---that's why you have
the Pi-Net following the tube for matching and harmonic reduction.....and
the antenna after that which is another broadband filter but not a very good
one.
I just wish AM broadcast band stations were required to bandpass their
emissions. But that is another subject.
My 2 cents.
N7RT
----- Original Message -----
From: "Larry Benko" <xxw0qe@comcast.net>
To: <amps@contesting.com>
Sent: Sunday, March 21, 2010 5:46 PM
Subject: Re: [Amps] Tuned Input for G-G 50Mhz amp
> We generally think of PI networks as "low pass" and Tee networks as
> "high pass" but there are PI networks and Tee networks of both "low
> pass" and "high pass" topologies. A low pass PI network (CLC) and a low
> pass Tee network (LCL) have different values of components but can be
> identical for input impedance, output impedance, and transmission at
> EVERY frequency. Having to absorb external components into the network
> may preclude the use of one topology or may restrict the range of Q. A
> low pass PI network and a high pass Tee network can be made identical at
> only one frequency.
>
> Larry, W0QE
>
> Carl wrote:
>> Ive used the T on a few conversions such as when I drove a low impedance
>> such as a 3 hole Alpha 76. The Pi is more forgiving when going from Eimac
>> to
>> Chinese 3-500's as an example
>>
>> I also use a T on the 2M 3CX1000A7 and 222 8877 as the operating range is
>> so
>> small its a set and forget and I wanted a high Q for selectivity to keep
>> the
>> unwanted transverter products way down.
>>
>> Carl
>> KM1H
>>
>>
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