[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [IRCA] C. Crane Twin Coil Ferrite AM Antenna (further comments)
Hi,
The yahoo Loopantennas group a year or so go had a thread about the Twin
Coil antenna, with reference to its Patent drawings, and how it actually
worked and what the "Twin Coil" really did. I bought a Twin Coil antenna
from C Crane, from their "returned" section on the webpage. The unit was
like new but less cost than the new price. Along with the patent info I
played with the antenna on the bench, taking it apart and deriving the real
circuit diagram (not the same as on the patent drawings). The patent was
full of deliberate misleading, outright wrong, and "obfuscating"
descriptions. One might think they were patenting something to be used in
the space program or some other secretive government agency instead of a
basic consumer product. At any rate I had fun learning about the Twin Coil
antenna.
But what I found out was it didn't work any better than the traditional
single coil tuned ferrite rod antenna. It is a good product, however, and as
someone noted, you can buy an optional extender cable to put the ferrite
tuning head away from local noise or even outdoors, and still tune it from
the base section by your radio. And it works as well or better as any 7.5
inch tuned amplified ferrite rod antenna that I've tried. I think it's a
good buy even at full price from C Crane. I wasn't aware until now that
Fry's sells it, and at an even better price, and no doubt it could be
ordered online, though you'd pay shipping--for those of us in areas where
there are no Fry's Electronics stores. And C Crane almost always has a
couple for sale as returned units for lower cost.
(Incidentally, "twin coil" means C Crane uses two pickup coils, mounted at
each end on the ferrite rod, with an RF transformer to combine their outputs
going to the amplifier. Varactor tuning is used, so the ferrite tuning head
can be tuned remotely. I was able to breadboard my own "twin coil" antenna,
and compare it with a traditional single coil asntenna, and thus find that
there was no advantage that I could see to using the twin coils as far as
giving an improvement in sensitivity. But the circuit was easier for a
manufacturing tech on an assembly line to adjust, using a twin coil
arrangement, for the particular circuit they used.)
Steve
----- Original Message -----
From: "Dennis Gibson" <wb6tnb@xxxxxxx>
To: "Dennis Vroomski" <vroomski@xxxxxxxxxxx>
Cc: "Steve Ratzlaff" <steveratz@xxxxxxxxxxxx>
Sent: Tuesday, January 06, 2009 6:49 PM
Subject: Re: [IRCA] C. Crane Twin Coil Ferrite AM Antenna
Dennis - thanks for your comments. Unfortunately the noise level outside
isn't much better than indoors. I've heard that under some circumstances
it can null noise and produce a signal than was previously unlistenable
due to the noise. In any case I'm sure it can do things that passive loops
can't.
What's nice is that including sales tax it will only cost me around
$25.00. Fry's sells it for $79.90; C. Crane sells it for $99.95. I have
two $30.00 Fry's gift cards. I'll get one Saturday; the closest Fry's is
about 40 miles away.
Maybe Steve can go into more detail.
73
----- Original Message -----
Date: Wed, 07 Jan 2009 01:58:26 +0000
From: vroomski@xxxxxxxxxxx
Subject: Re: [IRCA] C. Crane Twin Coil Ferrite AM Antenna
To: Mailing list for the International Radio Club of America
<irca@xxxxxxxxxxxxxxxx>
--
Dennis,
I have the Terk and the Twin Coil ferrite AM antenna. What's
nice about the Twin Coil is that you can place it outside to get
away from local noise inside the house. C Crane has a 25'
extension cable that they sell.
I used the Twin Coil in England out in the country. We stayed
in an old brick estate and I placed the antenna head outside
and it worked well. Also used it at Westport, WA and heard
some TP's on it.
If mounted outside it needs to be sealed from the weather.
I believe Steve Ratzlaff bought the twin coil. He could give
you a more detailed technical report than me.
Dennis,
Salmon Creek, WA
_______________________________________________
IRCA mailing list
IRCA@xxxxxxxxxxxxxxxx
http://montreal.kotalampi.com/mailman/listinfo/irca
Opinions expressed in messages on this mailing list are those of the original contributors and do not necessarily reflect the opinion of the IRCA, its editors, publishing staff, or officers
For more information: http://www.ircaonline.org
To Post a message: irca@xxxxxxxxxxxxxxxx