Re: [IRCA] C. Crane Twin Coil Ferrite AM Antenna (further comments)

[satya@xxxxxxxxxxxx]

Hey Dennis:

I looked at the patent for it, and the "twin coil" means that they take
the coil and split it in two halves, one on either end. So, you have the
same number of turns of wire, and therefore it does makes sense that it
works about as well as a standard single-coil loopstick, as Steve
mentions.

However, the ability to remotely orient it may be great for you, since if
there is a quiet spot somehwere in the RF jungle in which you live, you
could leave the loopstick portion there and DX in leisure in a chair
several feet/yards away. In fact, I wonder if more than one 25-foot
extension cord can be used: at such low frequencies, I bet there isn't
more than a decibel or two of loss, which is probably easily made up by
the RF amp in the base unit.

Kevin



> 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
>>
>
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