[AMPS] Reading Reflected and True (?) Power

[Jim Reid]

> Jim Reid wrote:
>
> >Conclusion:  More drive power is required to yield a given
> >power into a load which differs from 50 ohms

>Jon:

> I have to think a little about your statements.  While I don't doubt your
> experimental results, I would have thought that you would not see that
> variance in drive power.

More fiddling will follow,  hi.

I have just,  early this morning been reading in Walter Maxwell's
book,  "Reflections".  In Chapter 7,  section 7.5 he discusses
what is required to match a mismatched antenna "system" using
only the output circuit of the amplifier, he calls this the "tank";
however he uses a Pi output circuit in his discussion.

In any case,  he points out that with a non-conjugately matched
situation,  the amplifier tank will be faced with reactance.  If
the tank is not retuned to compensate,  the amplifier "will have
higher than normal disspation" and will also be either over or
under loaded depending upon whether the apparent R of
the antenna system at the tank terminal is greater or lower
than the tank R.  To set correct,  the amplifiere output circuit
must be retuned and the load capacitor readjusted!

I didn't do that in yesterrday's tests!  I left the tuning/loading as
set when loading into the Bird dummy load.  Maxwell also feels
that an RF ammeter in the output transmission line should be
used as well as the meters for forward and reflected power
to reach the correct match to the antenna system.  I have
a couple of RF ammeters,  will see what I can "rig" up to
handle the power levels of interest here.

More to follow.

73,  Jim,  KH7M



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