Joel,
Thank you for that explanation.
I was puzzled because neither in the text nor in the block diagram of
the test setup is there any mention of a tuner at the signal generator
end, and I can only see one tuner being used for the back-to-back tests
in the Figure 4 photograph.
I see some practical difficulties in adjusting the two tuners: the tuner
at the generator end will need to be adjusted whilst watching the
microvoltmeter at the load end 95ft away; and because the settings of
the two tuners will be interdependent it will necessary to iterate the
adjustments several times - not easy when they are 95ft apart.
73,
Steve G3TXQ
On 27/01/2012 17:17, Joel Hallas wrote:
Steve,
Good questions, and this goes back some time, as I remember it, we had the
line going into a 9:1 balun at each end. On the distant end, where the
microwattmeter was, we had the 50 ohm termination of the wattmeter. At the
generator end, on the coax side of the balun, we had a pi-network tuner (my
old 100 W tentec, appropriate for this forum). For each test at each
frequency, I adjusted the tuner for maximum response at the far end. My
conclusion is that the line was thus matched to the generator at each test
point. Whatever the transformed impedance of the far end (meter load) was at
the generator was matched for maximum power transfer to the system at
whatever impedance it was.
I hope that makes sense, and makes you more comfortable with our technique?
Regards, Joel Hallas
Westport, CT
|