16/04/2013 23:32
Thanks for the replies so far. I have taken a backward step and
decided to use the AIM 4170 to scan the stock factory 27.12 MHz Pi
input circuit. As I did not get the exciter with the RF Generator, I
cannot say for sure if it expects a 50 Ohm match, but assume it did.
I took some screen shots of various scans. The long file names are
pretty self explanatory. One scan is the the stock 27.12 MHz input Pi
network disconnected totally from the de-coupling caps on the valve
base. One is with a 50 ohm carbon composite resistor across the output
cap of the stock Pi network, with the network disconnected from the
rest of the RF deck. One is with this resistor still connected *AND*
the output of the Pi network connected back up to the de-coupling caps
on the valve base, with the valve in place. To be frank, I don't
understand what I am seeing. The cursor is around about 21.12 MHz in
each screen shot. The only one that seems to make any sense to me is
the one with the Pi network open at the output side....
I have added a screen shot of a page from the Eimac spec sheet to the zip
file. This makes me assume I should be aiming for a 50 Ohm match.
I feel I am doing something wrong, or expecting something
I shouldn't be! Thanks. Files are at:
http://www.chriswilson.tv/pi/Pi_scans.zip
Thanks!
--
Best Regards,
Chris Wilson.
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