[Amps] Pi network tuning

[Mike(W5UC) & Kathy(K5MWH)]

Thanks Tom.  The next question is;  Does it matter which side of the 
blocking capacitor I attach the termination to ground.  This is a 50 mHz 
amp, and to attach to the anodes would mean long leads. If I hang the 
resistor at the input to the pi-network, (across C1) the leads can be short.

73,
Mike, W5UC
http://members.cox.net/w5uc

----- Original Message ----- 
From: "Tom W8JI" <w8ji at w8ji.com>
To: "Mike(W5UC) & Kathy(K5MWH)" <w5uc at cox.net>; "AMPS" <amps at contesting.com>
Sent: Sunday, July 23, 2006 9:10 PM
Subject: Re: [Amps] Pi network tuning


>> Please try this question on for size.  With the pi-network built, and the 
>> tubes in the sockets and AC coupled to the pi-network, is it possible to 
>> determine that the pi-network values are correct by using a Grid Dip 
>> Meter to determine resonance of the network?  I have a 50 Ohm resistor 
>> hanging across the output capacitor.
>
> You won't know the impedance transformation, just resonance.
>
> The normal procedure is to terminate the anode to ground with the expected 
> tube operating load impedance and check for 50 ohms at the output port 
> with a low power SWR measurement device. You would also have to know at 
> least one component value reasonably close and not touch that component to 
> verify you are close to planned loaded Q.
>
> 73 Tom
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