[TenTec] balanced feedline light bulb test

[AC5E at aol.com]

Another discussion that brings back memories! 

No, a single lamp no matter how coupled, won't show balance. That takes two 
lamps, one for each side of the transmission line,  at the same time. And at 
that the difference must be considerable ( I keep thinking 15% or more, but I 
have no idea where that came from out of the dust of ages) for the eye to tell 
the difference. 

It's been better than a half century since I used one in any form,  homebrew 
bare open wire was the norm,  most of us had Windoms or random wires,  and we 
were darn careful not to come in contact with the feedline. Twice at any rate, 
and if you did you handled RF very carefully thereafter. In fact, I still 
don't trust the stuff and the scars are right there, and there, and there. 

Usually, there's no difference in lamp brightness no matter where on the 
feedline you couple to it - unless you get  the very odd situation where the 
standing waves are actually standing. With the drift we had that usually didn't 
last long. 

In that situation the variations in light intensity with an incandescent bulb 
are quite dramatic, with maximum brightness at a current maxima. A neon bulb 
coupled to the feedline will also light - but at voltage maxima.  

And yes, current is usually considered before voltage. I don't remember that 
being because of RF ammeters or light bulbs, but because the high current 
portion of an antenna is the part doing the bulk of the radiating. So we naturally 
wanted as much current in our antennas as we could get from our "one tube 
wonders,"  ARC5's, Stancors,  UTC's, or whatever we had. QRP was the norm because 
few of us could afford more.

73  Pete Allen  AC5E