Whoa, I did that experiment for Slick a month ago. I replaced the short
piece of LMR240 between the transmitter and Kenwood SW2000 meter with a
precisely measured 1/4 wavelength piece of RG59 75 Ohm coax. The loading
changed, as expected, but the SWR reading did NOT change for SWR values of
1:1 and 1.6:1. The transmitter now saw a load of 112.5 Ohms. The Kenwood now
saw a different source impedance.

I don't see any inconsistency. 100W into 112.5 Ohms requires a voltage of
106V RMS. In a transmitter with a fixed ratio output transformer that may
not be doable. It is designed to put out 70.7V RMS into 50 Ohms, with some
margin.

Tam/WB2TT
"Reg Edwards" wrote in message
...
To anybody interested.

We have a HF Transmitter + 50-ohm coax + SWR meter + Tuner + Feedline of
any
Zo + Antenna.


Suppose it is all tuned-up and ready to go. The transmitter is loaded
with
exactly 50-ohms resistive.


Now change the 50-ohm coax to shorter length of 75-ohm Zo.


As everybody agrees (after perhaps a little meter recalibration) the SWR
meter indication will not change. BUT THE TRANSMITTER WILL NOW BE
INCORRECTLY LOADED.


Where does the inconistency lie ? Does it lie in the change in effective
source impedance?

The inconsistency is that the power level changed, the load on the
transmitter changed, but the SWR meter gave no indication of it.

What's wrong ?

Reg Edwards wrote:

The inconsistency is that the power level changed, the load on the
transmitter changed, but the SWR meter gave no indication of it.

What's wrong ?

Nothing's wrong with the equipment. Something's wrong with the operator.
If you want to make the problem even worse, remove the coax entirely.
--
73, Cecil http://www.qsl.net/w5dxp



-----= Posted via Newsfeeds.Com, Uncensored Usenet News =-----
http://www.newsfeeds.com - The #1 Newsgroup Service in the World!
-----== Over 100,000 Newsgroups - 19 Different Servers! =-----