The pi network used in amplifiers is more than a low pass filter and
impedance matching device.
Due to its Q it has a resonant peak at the operating frequency which is much
greater than its low
pass characteristic. The same is true with the L-C-L pi network and its high
pass characteristics.
Much more that just low pass or high pass filters. In fact any time you try
to match two very differing
impedance with LC networks you end up with a resonant peak.
73
Bill wa4lav
________________________________________
From: Amps [amps-bounces@contesting.com] on behalf of Larry Benko
[xxw0qe@comcast.net]
Sent: Friday, July 10, 2015 12:30 AM
To: amps@contesting.com
Subject: Re: [Amps] L-C-L vs C-L-C
Ron,
There are 2 types of both networks (lowpass and highpass).
*C-L-C Pi* is a lowpass with the ability to ground one side of the
capacitors
*L-C-L Pi* is a highpass with both sides of the capacitors hot
*C-L-C Tee* is a highpass with both sides of the capacitors hot and this
is the common Tee tuner topology
*L-C-L Tee* is a lowpass with the ability to ground one side of the
capacitor
Larry, W0QE
On 7/9/2015 9:26 PM, Ron Youvan wrote:
>> -----Original Message-----
>> From: Amps [mailto:amps-bounces@contesting.com] On Behalf Of
>> chris@chrishays.com
>> Sent: Thursday, July 09, 2015 6:54 PM
>> To: amps@contesting.com
>> Subject: [Amps] L-C-L vs C-L-C
>
>> Another reason I suspect is the C-L-C pi network allows both the
>> variable
>> capacitor rotors to be at ground potential. This lets the shaft be at
>> ground potential making for a safer control that is not affected by the
>> proximity of the human operator's hand. No insulated shaft required
>> either!
>
> I am having a lot of trouble visualizing a C-L-C (usually called a
> "T" not a Pi)
> network where any part of either capacitor is grounded, please explain
> more.
>
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