[TenTec] Re. [Ten Tec] Grounds and balanced fed verticals

Joel Hallas jrhallas at optonline.net
Fri Jan 27 09:17:57 PST 2012


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

-----Original Message-----
From: tentec-bounces at contesting.com [mailto:tentec-bounces at contesting.com]
On Behalf Of Steve Hunt
Sent: Friday, January 27, 2012 11:45 AM
To: Discussion of Ten-Tec Equipment
Subject: Re: [TenTec] Re. [Ten Tec] Grounds and balanced fed verticals


I'm giving some thought to how I would replicate your experiment to 
satisfy my own curiosity, and I have a couple of questions about the 
technique you used.

 From your article I gather that when you changed the line conditions - 
made it wet, dropped it onto the ground etc - the characteristic 
impedance changed, and that you compensated by adjusting the tuner to 
ensure that the line remained matched; however as far as I can see there 
was no corresponding change in matching at the signal generator end. 
That would mean the generator was "seeing" a different impedance for the 
differing line conditions; consequently there would be a changing source 
mismatch-loss and the generator would deliver different powers to the 
line under the different line conditions.

I'm wondering:
1) When adjusting the tuner, how did you know when the line was matched?
2) How did you take account of the changing generator mis-match loss 
when calculating the line loss?

Please don't think I'm trying to "challenge" your technique, I'm 
genuinely trying to unravel some of the issues!

Steve G3TXQ

On 27/01/2012 13:52, Joel Hallas wrote:
> Steve,
> Thanks, yes I agree that it is important to be as correct as we can.
> I have confidence in our observations.
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