[Elecraft] Slightly Unbalanced dipole?

[Jim Brown]

On 1/14/2019 9:02 AM, Barry wrote:
> The simple answer is that the common mode chokes available to hams are 
> of the unbalanced type.

Huh? We're hams -- we're not limited to products we can buy! And we can 
build far better than we can buy. In 2010, I published the design for a 
common mode choke to cover the HF bands using a pair of #12 THHN wound 
on a 2.4-in o.d. #31 toroid.  k9yc.com/2018Cookbook.pdf has dozens of 
designs using THHN, teflon pairs, and RG400. These chokes are fairly 
easy to wind, and all can be built for less than about $35, including 
connectors.

A member of our contest club is building a serious contest station, and 
asked me to measure a "balun" from a well-known manufacturer. It came in 
a nice weatherproof non-metallic enclosure, and was nicely made. But it 
looked NOTHING like the data sheet that WAS on the website at the time 
(and which has been removed since I showed my data to a few engineering 
colleagues, one of whom obviously asked the mfr about it.)

The problem with choking a two-wire feedline is NOT one of balance -- if 
it's a good choke, the choke takes "balance" out of the equation. What 
matters is dissipation in the choke due to excessive voltage or current 
that is present because the antenna is not matched to the line.

73, Jim K9YC