[Top] [All Lists]

Re: [TowerTalk] HF Vee Beam Experience?

Subject: Re: [TowerTalk] HF Vee Beam Experience?
From: "Pat Barthelow" <>
Date: Thu, 13 Sep 2007 10:33:19 -0700
List-post: <>
One method of terminating Rhombics documented in a number of older references, that may eliminate the termination resistor, is to fabricate a long, tapered, unterminated, stainless steel or nichrome transmission line at the far end of the rhombic. The old army manual on rhombics shows this transmission line dissaaptor in their drawings as being dropped from the far vertex, and running back along the center line of the rhombic towards the center supported near the ground on small poles.

The rate of taper (convergence of the transmission line conductors) is what has to be determined, and also the lossiness of the nichrome or SS wire used. Done right, the lossiness of the tapered, terminating transmission line does two things, dissapates power, and provides a lossy return line for the reflected wave which returns from the distant, open end of the lossy line. Same as using a long piece of RG 58, unterminated, as a dummy load for testing of VHF transmitters.

All the Best, 73,
Pat Barthelow
Jamesburg Earth Station  Moon Bounce Team

From: "Chet Moore" <>
To: "Rick Stealey" <>, <>,<>
Subject: Re: [TowerTalk] HF Vee Beam Experience?
Date: Thu, 13 Sep 2007 13:13:51 -0400


OK, I'll bite. How well does it work I used a rhombic up at KL7AIZ that
was 500 feet per leg, terminated at the far end.. That one loaded on all
bands and was dynamite. A rhombic at this QTH is not feasable.

Press on regardless


Chet N4FX
----- Original Message -----
From: "Rick Stealey" <>
To: <>; <>
Sent: Thursday, September 13, 2007 10:11 AM
Subject: Re: [TowerTalk] HF Vee Beam Experience?

>>terminating resistors?
> Hi Henry,
> I homebrewed one a year ago, on the way to building a Rhombic (first half
> of
> my rhombic). It didn't do much for me in the way of excitement so I
> completed the Rhombic project and then only needed one terminating
> resistor.
> I was looking for a 500 watt 600 ohm resistor, and you are right, they
> aren't common items. I checked with a company called Carborundum I think
> it
> was, who make Globar resistors but they wanted something well over $100
> for
> it. Had to get them to "quote" my request, couldn't get a price from
> their
> web site. So I looked for alternatives and an interesting alternative was
> to get a 50 ohm dummy load and use a balun (an un-un in the case of a vee
> beam since you are connecting to ground) like a 9:1 type to match the 50
> ohms up to 450 ohms.
> As to performance... that's another subject, that's not what you asked,
> is
> it?
> Rick K2XT
> _________________________________________________________________
> Get a FREE small business Web site and more from Microsoft® Office Live!


> _______________________________________________ > > > > _______________________________________________ > TowerTalk mailing list > > >


TowerTalk mailing list


TowerTalk mailing list
<Prev in Thread] Current Thread [Next in Thread>