Towertalk
[Top] [All Lists]

Re: [TowerTalk] re Radials

To: Dave Tipton <dave@lodave.org>
Subject: Re: [TowerTalk] re Radials
From: Jim Lux <jimlux@earthlink.net>
Date: Fri, 16 Jun 2006 11:12:27 -0700
List-post: <mailto:towertalk@contesting.com>
At 10:16 AM 6/16/2006, you wrote:
>Well.. I have an old 5BTV (Hustler) that I'm going to put up this 
>weekend...  It is spec'd for 1/4 wave radials on each band, telling me 
>that I need to have 3 on each band...

I believe that is for resonant radials, suspended some way above the ground.

>
>MY question...  If I were to lay down 8 radials on 80, 80 on 40 and 8 on 
>20 (The only 3 bands I'm really interested in), do you think this would 
>give me sufficient performance to rely on it for some medium distance work?


Lay down, as in put on the surface of the ground or close to it?  If so, it 
doesn't matter what length they are... they're non resonant.

>  I'm not going for big DX here, but I'd take it if I heard it.. I now 
> have an 800 watt amp in the mix too, so I'm going for as near resonant as 
> I can get.


Have you got a tuner?  Just throw out your radials, tune the sucker up and 
go for it.  I have a set of 6BTVs in my back yard that I fool with. The 
radials are just lengths of AWG12 insulated wire stretched out in various 
directions on the surface until I hit an obstacle (like the fence or the 
house). When I put the first one up, I measured the feedpoint Z on all the 
bands, and darned if some weren't resonant too high, and others too 
low.   Worse than that, it changed depending on how recently the lawn had 
been watered. I was not looking forward to tediously readjusting it.

So, I loaded everything into XLZIZL and calculated what the (additional) 
loss would be from the mismatch, figuring in a tuner (at the Tx end of 75ft 
of RG213 type coax), and discovered that the WORST case was <0.5dB.

Subsequently, I have thrown out a few more (untuned) radials, and the 
effect is more that the Z doesn't change as much depending on soil moisture.
Jim, W6RMK 


_______________________________________________



_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk

<Prev in Thread] Current Thread [Next in Thread>