[Premium-Rx] Super ferrite rod aerials

[John Reed]

For those of you interested in really monstrous ferrite loops, a good friend 
of mine built one that consisted of 112 bars of 12"X3/4" rods.  It was 16 
feet long and could be rotated with some effort since the ferrite alone 
weighed about 100 pounds.  The performance was on a par with smaller 
monsters of about 4' length however. Sadly the 16' loop was destroyed by a 
tornado in 2000 here in Oklahoma.

John Reed

----- Original Message ----- 
From: "Ben Dover" <quixote2 at ix.netcom.com>
To: "Rick Warnett" <servicemgr at prosec.com.pg>; <premium-rx at ml.skirrow.org>
Sent: Wednesday, August 03, 2005 2:57 AM
Subject: Re: [Premium-Rx] Super ferrite rod aerials


> Funny you should mention monster ferrite antennas.
>
> After working with air core loops for a number of years, I've been working
> with a monster ferrite design of my own here for the last six or eight 
> months.
>
> I've been going for LF and VLF coverage, and the air core design model 
> hits
> a brick wall re. practical dimensions for amateur designing at about 100 
> KHz.
> The additional permeability of a big ferrite core makes things a whole lot
> easier mechanically, and makes very efficient VLF recieving antennas a 
> quite
> practical proposition.
>
> I won't go into a whole lot of detail here, but my designs are based on a 
> LOT
> of toroid cores stacked to make a BIG ferrite rod...   say, 3 to 8 feet in
> length and over an inch in diameter. The basic loop design uses a low 
> noise
> FET preamplifier (perhaps 25 - 30 DB of gain). A lot of it's structural 
> design
> is based on PVC plumbing fittings and pipe. Except for the tedium of 
> winding,
> construction from scratch is easily done with hand tools, plus the usual 
> PC
> board work to build the preamplifier.
>
> So far, I've built two of them successfully. With a 60 - 2200 pf variable
> cap for tuning, the first went 20 - 100 KHz, and the second (still in the
> late stages of construction) tunes roughly 7.5 - 24 KHz.
>
> If anyone is interested in them, my Yahoo group, LF / VLF HANGOUT, has 
> some
> messages from me with detailed information on the antennas, as well as a 
> lot
> of pictures made during construction as well as the finished product.
>
> If you don't want to join Yahoo groups, E-MAIL me off the list and I'd be
> happy
> to send you the picture files, and answer any questions you might have.
>
>
> 73's,
>
> Tom, W9LBB
>
>
>
>
> At 10:26 AM 8/3/2005 +1000, you wrote:
>>I recall seeing a monster ferrite aerial in the LWCA magazine pages some
>>years ago, made of "a lot" of smaller rods glued together. It was rotated 
>>on
>>a small trolley and was reported to work quite well. It was several meters
>>long and I think about 2" in diameter. You might need to find a closeout
>>sale to match this !!
>>I have made several smaller composite rods and they all exceed single rod
>>performance.
>>Rick
>>
>>
>>
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>
>
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