On Fri, 4 Dec 1998 10:40:34 +0000, Steve Thompson
<amps@txrx.demon.co.uk> wrote:
<snip>
>Should do - Often the accuracy on Z meters goes out a bit at 1000's ohms
>so it's also worth doing it the other way round - replace the tubes with
>equivalent R/C combinations and look for 50 ohms looking into the
>antenna socket.
>
>Steve
______________________________________________
The MFJ-259 antenna analyzer works very well for this. With the amp
off, connect a 1/2 watt resistor equivalent to the tube's impedance
from plate to ground, then connect the MFJ to the output connector and
set it to the frequency desired. If there is a relay in there, either
activate it or bypass it. Tune the input and load caps until the MFJ
is seeing 50 ohms and there you are. Works like a charm. Don't
forget to remove the resistor before you turn on the amp or you'll get
a demonstration of how well a 1/2 watt resistor dissipates a couple
thousand watts... :-)
73, Bill W7TI
--
FAQ on WWW: http://www.contesting.com/ampfaq.html
Submissions: amps@contesting.com
Administrative requests: amps-REQUEST@contesting.com
Problems: owner-amps@contesting.com
Search: http://www.contesting.com/km9p/search.htm
|