[TowerTalk] Steve Best's Forward/Reflected Voltages

[Jim Reid]

Steve, you wrote,  in part,  to explain   the series
of waves on the line:

> This process continues until the steady state conditions are reached.  The
> total forward traveling voltage delivered to the transmission line in the
> steady state is simply the sum of all of the forward traveling voltage
terms
> at the input to the transmission line.  Yes, this is a geometric series
that
> can be represented in the form of 1/1-a.  In this case, a = rhoS rhoA
> e^-2GL.  The total steady state forward traveling voltage is given by
>
> Vforward = Vi 1/(1 - rhoS rhoA e^-2GL)

So today I rechecked  and took some more numbers,  hi!
They may be of no added value to you at all,  but I am
"into"  this whole project now,  hi!

Maybe the voltages I measured would be of some use.

Realized that my RF Applications P-3000 set up can also
record the voltages on the transmission line.  Using the
exact set up as reported before,  power,  frequency,
2.9 vswr line/antenna system,  etc.

Again,  with 1000 watts constantly monitored into the
tuner input  terminal,  found the following:

1.  P-3000 meter read 1.6 kW forward power;  387 to 400 watts
reflected power;  forward voltage of 292 to 302 volts,
reflected voltage of 132 volts.  P-3000 meter indicated a
vswr on the line throughout the tests of 2.9 to 3.0:1.

1.1 Replaced P-3000 coupler on the output transmission line
to the antenna with the Bird 43 wattmeter.

a.  With the 2500 watt Bird slug,  read 1200 watts forward power,
340 watts reflected.

b.  With the 5000 watt Bird slug,  read 1200 watts forward power,
260 to 270 watts reflected.

c.  With the 500 watt Bird slug,  read 250 watts reflected.

Conclusion:  Bird readings are certainly within tolerances
just as before.  However the RF Apps.  P-3000 readings
of power are higher;  don't know why as the meter and
coupler were both checked out at the RF Apps plant in
Mentor,  Ohio back in March of 1999.  However,  they
calibrate the set up at 14100 to within plus or minus
10%,  plus or minus the analog to digital converter
resolution,  which in my case is 256 power steps
(8 bit resolution) from zero to 5000 watts (I have put
in the optional 5 kW chip).  Were I to take the time,
I could recalibrate the unit at the test frequency,
7.088 mHz,  but still would be the same error window.
Perhaps this all adds to the higher numbers read,
seems as if there must be something else.

Just more of the same,  I guess.

73,  Jim,  KH7M


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