[TowerTalk] Type 31 baluns

[Jim Brown]

On Tue, 01 Jun 2010 19:36:40 -0700, Kevin Normoyle wrote:

>We started this saying the baluns at balundesigns could be outdone. I've 
>not seen the one true answer that makes me believe that yet.

One true answer? Gee, I've published measured data and showed exactly what 
I measured and how I measured it. Have you gotten that from any mfr of any 
balun or similar product? 

>What I think i see is a little bit of a cheat: tuning baluns so you say 
>they're "better" for restricted ranges within 3.7-30mhz?

3.5-30 MHz is hardly a restricted range -- it's all but one of the HF 
bands. How many hams have antennas that cover that much range?  I don't 
have any. 

One BIG difference is that I've published designs and shown them to be 
superior to the published specs of vendors like CalAV, and I've shown 
mueasured performance of several DXE products. These designs, WHICH I HAVE 
GIVEN AWAY FOR FREE, are quite superior to virtually anything you can buy 
for more than $100. Look at the mfr data for the CalAV chokes, and at my 
measured data for the DXE chokes. NONE of those products covers more than 
half of the spectrum that my designs cover, and cover far better!  

A cheat?  Heck no, I'm simply being honest about my designes, with no false 
marketing claims! And I'm also FAR more demanding about performance. Most 
choke mfrs think 500 ohms is enough. Both W1HIS and I have shown that 5K is 
what's needed. And that number is what the DoD paper came up with in 1966. 
Their design was for three chokes to cover that range. 

If you READ what I posted yesterday, you should have noted that I said that 
the bifilar chokes wound with enameled wire are close to 50 ohms, while 
those wound with THHN are close to 100 ohms. The THHN chokes will add a bit 
of mismatch above 7 MHz (where the length of the line in the choke is 
enough for the transmitter to see some mismatch). Is this a big deal? It is 
if your amp can't tolerate some modest mismatch. If there's a tuner between 
the amp and the choke, it doesn't matter. 

Traditional W1JR chokes, which are wound on #61 material, cover only one 
ham band, and the band that they cover isn't specified, and the builder 
doesn't know what it is, because he doesn't know how measure it. But the 
mfr of these chokes claims that they cover the entire HF spectrum. 

73,

Jim K9YC