>One question I have been meaning to ask........
>
>Can someone please clarify "Loading" ??
>
>When I turn my LOAD counterclockwise (CMDR HF2500), the grid current drops
>quickly with little drop in output pwr (as recommended). Am I increasing or
>decreasing the loading of the antenna ???
>
Increasing the load setting [less C2] beyond that which produces
optimal power transfer decreases the step down transformation ratio of
the tank, which means that the 50 ohm load now look too low for the way
the tank has been adjusted. .
>I think I am increasing the loading (even thought the dial is going to a
>lesser #), However, I think I read somewhere (maybe an Ameritron AL800H
>manual) that seemed to contradict this (or their var. cap works in the
>opposite direction - increased loading shows higher dial #) .
>
In most amps, the max. indication on Load is min. C.
>I interpereted an earlier post as saying not to drop the grid by adjusting
>the load, rather decrease the drive from the exciter.
>
>Sometimes I wish I was born 20 years earlier so I could have been taught
>tubes rather than solid state when I was in school .
Tubes work pretty much like TMOS FETs. Murphy's Law applies equally to
both. Some things you can not learn in school. In the college I
attended for 3 years before I got booted, electronics engineering majors
were taught zero about parasitic oscillation.
later, Eric
cheers
Rich...
R. L. Measures, 805-386-3734, AG6K
--
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
|