It’s a thick walled plastic nema box.... and toroids are type 31, not type
33.
7-17 female connectors on each end. Existing chokes consist of 4 turns of
393
through 4 x type 31 cores. Steve, G3TXQ tried 4 x turns of 213 through 4 x
cores and
found the Z was a little over 3 k ohms from 13-27 mhz. I need to use one
box for 15m,
and the 2nd box for 20m. Without mucking it up too much, I believe I can
add at least
one more core, perhaps 2 cores to the 15M box....and possibly 2-4
additional cores
to the 20m box.
I also need to build two more boxes, one for 80m, and the 2nd for 40m.
These are all monoband
chokes, so they only have to work good one one band. I think the max turns
that can be stuffed through
these 1.4 inch ID cores is aprx 5-7 ? 393 coax is is bit smaller OD vs
213. .391 inch vs .405 inch.
Something else I cant fathom is the use of cores on both sides of the coax
loop. IE: 3-5 x cores
at 9 oclock position...and 3-5 at the 3 oclock position...... vs 6-10 cores
all stacked on one side.
K9YC sez the binocular format is not optimum. I just don’t understand why.
I only have so much
room in these nema boxes... so cant have huge loops on the outside of the
cores. I also cant
have loads of space between the loops on the outside. I can only cram so
many torroids in there
and only on one side. Think it was like 6-7 max. Im also trying to
extrapolate K9YCs info, plus factor in
tight turns, with no space between em. 6-7 x cores + 5-7 turns might do
the trick for either, or 80
and 40m. I need to optimize for 80 and also 40m, separate chokes, the
best I can, with the
constraints I have.
Jim VE7RF
-----Original Message-----
From: Ian White
Sent: Monday, February 09, 2015 11:42 PM
To: 'Jim Thomson' ; towertalk@contesting.com
Subject: RE: [TowerTalk] Cutting a FT-240 type 33...in half ??
Hold on, Jim -
Please say that <isn't> a metal NEMA box with flange connectors at both
ends?
73 from Ian GM3SEK
-----Original Message-----
From: TowerTalk [mailto:towertalk-bounces@contesting.com] On Behalf Of
Jim Thomson
Sent: 10 February 2015 05:56
To: towertalk@contesting.com
Subject: [TowerTalk] Cutting a FT-240 type 33...in half ??
Ok, I have a requirement where an additional one or two x 2.4 inch
OD,
type 33 cores needs to be added to an existing choke balun.
Since each end of the RG-393 silver plated + teflon coax is already
silver
soldered to a 7-16 DIN connector at each end of the nema box,
I would rather not have to take the entire assy apart. Major pita.
393 coax
has TWO silver plated braids, and in this case, each of the braids has
been
carefully
separated at each end, and each braid is silver soldered to a lug,
that is
bolted to the 7-16 din connector flange, via the SS 8-32 machine
screws.
IE: 2 of the 4 corners of each 7-16 din female coax connector gets a
braid
attachment.
Can a 2.4 inch OD, 1.4 inch ID, type 33 toroid be cut in half, edges
sanded,
then placed around the existing 4-5 turns of 393 coax, then
held together via glue, ty-raps, both, or some other method ??? I
have an
excellent H-V bandsaw, made for cutting steel, hard steel, and AL.
IE: 80-120-200 ft per minute. It would slice through a toroid very
quickly.
If what I propose is feasible, it would save me a lot of grief.
I already checked, and the big, type 43 snap on types will not fit,
since they
only have a 1 inch ID.
Tnx...... Jim VE7RF
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