[TowerTalk] Reflections, Tuners and Antenna Forum Talks

[Jim Reid]

Hi,  David was wondering about part of my earlier
post:

> Somewhere between 50 and 150 watts of the RF that the 
> Henry shipped out though the Palstar tuner was eventually 
> lost in the coax or tuner?

Nope,  don't think so.  The 2500 watt Bird slug is only
accurate to be within +/- 125 watts across its power range!
So can easily cover a 50 to 150 watt measurement
with tolerance inaccuracy.  And I had to use that slug
to measure the forward power which was above
1000 watts.  Too bad  Bird does not have a 1500
watt slug;  would sure be neat for us amateurs!
And of course the 1000 watt slug has a tolerance
range of +/- 50 watts  anywhere in its' range.

Must look at a bigger picture when using non-lab
type test gear,  as I was.

There have been a few more posts twix Steve and I
today.  And I have performed more tests/measurements
at his request.  The idea:  to try to chase out some of
the measurement error tolerance problems.  Let's
wait and see what Steve comes up with in his more
complete analysis of the info I have provided him today.

Besides,  I made an error yesterday which I pointed
out to Steve today.  I did not measure the Z presented
by the antenna "system" here in the shack correctly.
That is,  I was too far down line when measuring the
Z at the input end of the shack to antenna transmission
line.  And when that line is NOT terminated in its'
characteristic Z,  as it is not,  since it is connected
to the Force 12 dipole some unknown total line
length away to an antenna which is most certainly
not a 50 ohm pure resistive load at the test frequency
of 7.088 mHz.

Yesterday,  I reported to Steve in my post that the
measured Z here in the shack was R = 52,  X = 58
ohms,  and vswr,  2.8:1.   But moving up by the tuner 
where the line actually connects to the tuner output,  found 
the Z measured there to be R = 17,  X = 11, vswr = 2.9.
But note the relative constant vswr number;  this is
exactly the way a mismatch line operates.  Z varies
constantly along the line;  however,  the vswr
remains constant (to within the measurement error
of the instrument,  in this case an MFJ-259B).

However,  now have numbers which make more sense,
I think based on further measuring going on today, hi.
Will let him use the numbers he requested for whatever
analysis he is doing.

Will await Steve's use of all this and his post to come.

73,  Jim,  KH7M






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