[Lowfer] a thought on coils

Thu, 14 Feb 2002 16:57:30 -0500

The questions I have are: 1) no knowledge of what ferrite; 2) where can
I get some/a lot of, litz wire; and, finally: 3) what was the freq?

73  Ed Tanton  N4XY  <[email protected]>

Ed Tanton  N4XY
189 Pioneer Trail
Marietta, GA  30068-3466

website:   http://www.n4xy.com

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-----Original Message-----
From: [email protected] [mailto:[email protected]]
On Behalf Of john hoopes
Sent: Thursday, February 14, 2002 2:15 PM
To: [email protected]
Subject: RE: [Lowfer] a thought on coils

Bill, although I have never personally experimented with ferrite loaded
coils, I have read various articles with the data claims you mention. It
seems pretty discouraging at first, and had it not been for my visit to
Walt's, I would have never given ferrite loaded coils a second thought.

Walt went into some detail about his coil but the only thing I can
remember is that the PI windings were jumble wound. That struck me as
rather odd, but who am I to argue with success. I know Walt was a
stickler for efficiency. He told me "If it isn't efficient, I'll rip it
out."

From what I can remember, the coil was enclosed in what appeared to be a
4" piece of PVC with end caps. Total length seemed to be 4" or so but it
was hard to tell because the coil was mounted at the top of his antenna
just underneath the top hat. I must admit I was a little disappointed at
first because I expected to see a huge coil at the base of his tower.
Instead there was a small aluminum box that housed a matching network
from the transmitter to the low Z of the antenna.

BTW, Walt used a home brew transceiver for both transmitting and
receiving that was a beautiful piece of work. It is too bad that Walt is
no longer in the hobby because his contributions are truly missed.

73
John/AB4MS/JDH

 -----Original Message-----
From: 	[email protected]
[mailto:[email protected]]
On Behalf Of Ashlock,William
Sent:	Thursday, February 14, 2002 12:15 PM
To:	'[email protected]'
Subject:	RE: [Lowfer] a thought on coils

Hi John,

>The simplest coil I ever encountered was made by Walt
>Glazar, W3WI. His beacon WI was heard all over the East coast as well 
>as
the
>mid west and it consisted of nothing more than a PVC form with two pi 
>wound litz sections over a small ferrite rod. Walt was a stickler for 
>efficiency and if it didn't perform, it didn't stay in his beacon. 
>Ferrite is very useable if you don't saturate it with too much power 
>provides an easy way
to
>tune a coil to resonance.

I have spent many hours trying to design loading coils using various
types of ferrite cores because they appear to offer reduced size and
ease in construction. The best Q I have been able to obtain is approx
100 at 150ma of current. Turns out it is very easy to saturate ferrite
cores. I have seen boasts of transmitting performance for these coils
from many sources, but when it comes to the actual coil Q, at the
typical 150ma antenna current, there's always a conspicuous lack of
data.

Speaking of simple coils, using Litz on a 4" PVC pipe (preferably with
slots) a Q of >300 is no problem at all. Not sure why the 'bucket
brigade' approach is so popular, except for the lower cost of the house
wire. The Rac for #14 copper wire at 185k is not really that good
because of the 'skin effect' losses.

BTW: Do have or can you get some more details about WI's loading coil?

Bill

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