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Re: [TowerTalk] CMC-230-5K

To: towertalk@contesting.com
Subject: Re: [TowerTalk] CMC-230-5K
From: Jim Brown <jim@audiosystemsgroup.com>
Reply-to: jim@audiosystemsgroup.com
Date: Thu, 21 Apr 2016 00:50:05 -0700
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
On Wed,4/20/2016 6:29 AM, Jim Thomson wrote:
###  By the time I buy 4 x torroids from one vendor PLUS shipping, then a pair 
of
those special one off  SO-239s  he uses, no Z bumps,  silver /teflon 
/gold...PLUS shipping,
then double shielded teflon coax, with silver braids + silver center 
conductor...PLUS shipping,
then a UV /water proof enclosure... PLUS shipping, then 4 of the one off nylon 
tie downs, that
are machine screwed down...PLUS shipping....and assuming I have the SS hardware 
on hand
plus the required gear to silver solder and terminate the ends, I decided I 
will save next to nothing.
In fact, I would save nothing.

You would save a lot if you did what I recommended about 8 years ago -- get together a group purchase and buy in quantity. I've been part of at least half a dozen, two of which I've organized. Appendix One of my tutorial lists Fair-Rite part numbers of some useful parts and lists several good industrial vendors who sell in quantity at great discounts. Remember - we need these parts not only for feedline chokes, but also to kill the many RFI sources that most of us have in our homes, and that are in the homes of our neighbors.


##  sometimes mucking about, dealing with in this case, at least FIVE  
different vendors, and shipping
on all FIVE, assuming no screw ups, and  hoping it all arrives intact,  I spend 
more time  rounding this stuff
up vs  building it. Shipping from USA to canada is not cheap.

I've also organized several group purchases of Amphenol 83-1SPs, and assorted audio connectors of the type we use around the shack. I'd be very surprised if there are no distributors of Fair-Rite and Amphenol in Canada.


##  I don’t see any  plug and play  cook book designs  by anyone, that  covers 
the 2-30 mhz
spectrum, with a sky high  8-12k Z, that  fits into a very compact 6 long x 
4.375  wide  x 2  tall box,
that weighs exactly 1.8 lbs.

Don't you recognize an advertising claim when you see one? I'm not trying to sell you anything, I publish measured data on the chokes, AND tell you exactly what's in them and how I measured them. Do you see ANY of that in the magic boxes you're buying?
##  he offered FREE shipping to Canada on a completed, plug and play unit.  It 
was here real fast.
I wish I had the megabuck worth of test gear to do my own experimentation on 
CMC chokes.
Nobody has managed to overheat a CMC-230-5k....yet.

It's a brand new product, Jim! And you really believe a mfr is going to tell you about his failures?

You will literally  melt the traps in any
Mosely pro-96 yagi long b4 the cmc heats up.   Ditto with the xfmr inside the 
stepir yagi.


##  To increase power handling capability of a CMC, there is a few ways to do 
it, and that depends on
how much spectrum it has to cover. More cores + less turns is one technique.

WRONG!

Cascaded CMCs is another technique.... or a combo of both techniques.    Sky 
high Z + RS is another concept.

I published my take on this 6 years ago, and what I wrote about it was not smoke and mirrors. I also have written about specific single core chokes that failed at high power.

73, Jim K9YC
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