Re: [IRCA] Antenna Projects (Crate Loop)

["Chris Knight" <chris@xxxxxxxxxxxxxxx>]

Hi Dave,

My strategy for the pickup loop "sense coil" will be a wire loop of one-turn
(possibly two turns like Kevin did) around the crate. For the connecting
cable, I plan on using a small length of 300-ohm TV lead-in wire (like this,
but smaller (10 feet)
http://www.radioshack.com/search/index.jsp?kwCatId=&kw=tv%20lead%20in%20wire
&origkw=tv%20lead%20in%20wire&sr=1 ). The pickup loop can be the same kind
of wire you used to string around the crate. After winding the pickup loop,
strip about an inch of insulation off each end of the pickup loop. Next,
take one end of the TV lead-in wire and strip it back about an inch exposing
both wires. Connect both sides of the pickup loop to the each of the 2 wires
on the end of the TV lead-in wire, one for one. Soldering these together is
a good idea. Then strip an inch of insulation off the other side of the TV
lead in wire, exposing the two wires on that end. That side will plug into
your radio (Drake R8 in my case). One side will plug into the 500-ohm
antenna terminal and the other side will plug into the Ground terminal. It's
a good idea to tin the ends going into the radio with a little bit of
solder, especially since each of the two conductors consists of strands.

What radio do you have? If your radio doesn't have plug-in antenna terminals
like mine, you will need to use 50-ohm coaxial cable instead of TV lead-in.
The only problem with that is the impedance mismatch, which even occurs with
the TV lead-in, but might not be enough to worry about. The tuned loop which
is a tank circuit has very high impedance. Matching using a toroidal
inductor is possible. Has anyone tried that with success?

Hopefully this explanation wasn't too confusing. If you have any more
questions, please let me know.

73 and good luck!

Chris

-----Original Message-----
From: HASCALL, DAVID CIV DFAS [mailto:DAVID.HASCALL@xxxxxxxx]
Sent: Friday, January 02, 2009 2:03 PM
To: irca@xxxxxxxxxxxxxxxx; chris@xxxxxxxxxxxxxxx
Subject: RE: Antenna Projects (Crate Loop)


Hi Chris - I had asked about "direct coupling" of the Crate Loop to a
receiver's antenna terminals and Kevin graciously replied and mentioned
it needing a "sense coil" (as you also noted).  He stated that he may
have to try that in the future.  This seems to be one of the easiest
loop plans that I have seen and maybe there is hope for me - a "tech
dummy."

73,
Dave in Indy


------------------------------

Message: 5
Date: Fri, 2 Jan 2009 13:34:28 -0700
From: "Chris Knight" <chris@xxxxxxxxxxxxxxx>
Subject: [IRCA] Antenna Projects
To: "Mailing list for the International Radio Club of America"
	<irca@xxxxxxxxxxxxxxxx>
Message-ID: <MDELJBGOEGKHBKJNEBBFKEFOCAAA.chris@xxxxxxxxxxxxxxx>
Content-Type: text/plain;	charset="iso-8859-1"

The Crate Loop looks like a great project and I'm going to start
building
one this weekend to use with a Sony ICF-SW7600GR (light, but not
ultra-light) and perhaps with the Drake R8 (using a pick-up turn of
wire).
The only problem here is the computer hash (5 computers at this QTH).

The helically-wound vertical posted by Craig Healy may be the answer to
the
computer noise. The plan is to build a scaled-down version to go next to
the
computer in the shack as a noise sense antenna and attempt to phase out
some
of the hash.

Thanks guys for the great ideas/designs and for posting them! 73.

Chris Knight
Fort Lupton, CO


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