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Re: [TowerTalk] RG-304 for CMC ?

To: towertalk@contesting.com
Subject: Re: [TowerTalk] RG-304 for CMC ?
From: Jim Brown <jim@audiosystemsgroup.com>
Reply-to: jim@audiosystemsgroup.com
Date: Sun, 24 Apr 2016 22:44:40 -0700
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
On Sun,4/24/2016 9:35 PM, Jim Thomson wrote:
##  Bunched up loops  lowers  res freq.
Right.

   Depending on choke  config, it can narrow the range of the choke,

Not if the core material is #31 or #43.


to the point where it covers 80m  with high  5-6 k RS... but not 40m.
Lousy on 40m, like 650 ohms.    This appears to be the case  when  Binoc
config is used in some cases.   With binoc config, with torroids at the 9 +
3  oclock positions, the turns all end up bunched  together for the entire 
loops.
Bad news  if  LMR-400 /213-U /393  coax used.   A LOT more C  between turns
with the .405 OD cables...vs  58-U / 303 etc.

This is nonsense.


##  One  advantage to binoc config, is you can then wind in 1/2 turn 
increments, like
4 -  4.5 – 5  - 5.5  etc.

This is also nonsense. Chokes wound for the HF bands using #31 and #43 material have VERY low circuit Q, typically on the order of 0.4. This makes them broad as a barndoor! Their tuning is NOT critical.


## 12 inch diam loops is a trick to maintain spacing between each loop.   With 
loops
equally spaced around the cores, now you end up with a mess that is almost 2 
foot in diameter,
which is exactly what I dont want for a cmc...esp on a 80m rotary dipole, 
mounted 10 ft up
the mast.     8.5 K in a little box, on 80m, with the CMC-230-5K is a more 
elegant solution.

## 12 inch diam loop = 3 ft in circumference.  7 turns = 21 ft of  
LMR-400..which is a lotta
weight,bulk,windload, etc.  But it does provide outstanding high Z / RS  across 
80+ 40m..and
160m.

I don't know where you get this stuff, but it's nonsense.

73, Jim K9YC

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