[AMPS] Input pi-net

[Rich Measures]

>
>Hi all,
>
>I designed a switchble input pi-net for my 'two-holer' (a pair of 8877's). 
>The
>calculated Z  is aprox. 23 ohms. The circuit is located close to both input
>blocking caps and tubes. I tested this circuit with both tubes connected to
>the sockets and a 23 ohms resistor cross to both blocking caps. I tuned this
>pi-net for all bands. As source generator I used the MFJ Antenna Analyser 
>259.
>All settings was nearly SWR 1:1 and I was satified. Later, under real power
>conditions all values are away up to 2:1 and higher. 

€  The best load is the real one.  

>I know my first test was
>made under static circumstance and in the real world it works under dynamic
>conditions. But I do have no chance to tune the network under operation
>conditions (no possibilities).
>Is there to go another way to fix it right under 'could conditions'? 
>Otherwise
>I have to make a new metal design to operate the input pi-net parts under
>power conditions.
>Maybe it would be better to test this circuit with more r.f. power than the
>MFJ 259 produces???

€  The cathode Z of a GG amplifier is unlike a resistor.  

-  cheers, Werner
>
>
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>



Rich...

R. L. Measures, 805-386-3734, AG6K, www.vcnet.com/measures  


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