[TowerTalk] Balun question

[Jim Brown]

On Thu, 14 Jun 2007 15:07:59 -0400, jeremy-ca wrote:

>I last looked.
>Since many hams tend to be cheap their view of ordinary coax would give 
>excessive leakage from the center conductor and possibly creating all sorts 
>of non linear problems with the ferrite.

Anything is possible, of course, but coax would have to be pretty awful for 
enough field from the differential signal to cause significant heating. You can 
convince yourself of this by winding some chokes with lousy coax, transmitting 
through them, and feeling the heat (or lack thereof). If more people did this, 
there would be a lot more weeping and knashing of teeth about dissipation in 
chokes. I can imagine crummy coax on a 100 w transmitter, but that's a lot less 
likely with the ham is running QRO. 10% leakage is a LOT of leakage, and that's 
only 10 watts with a 100 w transmitter. 

In the tutorial, I described a simple series of experiments that any ham can do  
with some toroid cores, some twinlead, some coax, and a 100W transmitter. The 
results are quite instructive. 

73,

Jim Brown K9YC