[Antennas] Rotary Joints for Ladder Line

2002年4月28日 11:52:35 -0400

I have never heard of this kind of system. I wonder if anybody has such an old
handbook and can make a copy for me. I will pay copy and mailing costs or fax
costs.
73, Joe
Karl Kanalz wrote:
> The ARRL "Handbook" (older editions, say prior to 1950) had construction
> projects for a three-element
> 20M beam, mounted on a "stub tower" on top of a house roof (made of wood!)
> and using a "rotary joint" for open-wire feedline.
>> Essentially, it was two large loops of copper tubing - one mounted (fixed)
> on the tower (with insulators, of course), and the other coupled *just above
> it* on the rotating part of the antenna mast assembly. As the antenna was
> rotated, r.f. energy was coupled from the (fixed) lower "loop" (about 12
> inches in diameter as I recall) to the upper (moveable) loop which then fed
> the driven element (balanced feed) of the Yagi.
>> The loops were un-tuned, too, so it should work for a tri-band system such
> as your KT-34
>> -----Original Message-----
> From: [email protected]
> Sent: Saturday, April 27, 2002 10:17 AM
> To: Pat W
> Cc: [email protected]
> Subject: Re: [Antennas] VSWR on Log Periodic.
>> Wow!
>> No problem on transmit, just crank up the power, but that is a pretty
> heavy hit on the recieved signal.
>> Guess I will stick with my KT-34. It is very close to 1:1 on all three
> bands at the antenna.
>> Or does someone have a good design for a rotary joint for use with
> ladder line?
>> Thanks Pat,
> Frank Kamp
> K5DKZ
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