[TenTec] G5RV

Frank Holladay holladayfd at multipro.com
Sun Feb 1 16:23:07 EST 2009

There is a LOT of difference between 100 feet and 199 metres!
Frank, K4VMO

----- Original Message ----- 
From: "Steve Hunt" <steve at karinya.net>
To: "Discussion of Ten-Tec Equipment" <tentec at contesting.com>
Sent: Sunday, February 01, 2009 2:50 PM
Subject: Re: [TenTec] G5RV

> Jerry,
> Yes, I'm sure. According to the VK1OD on-line calculator, at 3.8 MHz 
> 100m of RG213 with 14-j1 as a load has a loss of 1.9dB; 100m of Wireman 
> 551 with 14-j1 as the load has a loss of 3.1dB. I'm not saying the 
> difference is particularly significant - I'm just pointing out that 
> ladderline is not always lower loss than coax - it depends on the load 
> impedance.
> Incidentally, be wary of those ARRL charts which tell you what the 
> "excess loss" is for a particular VSWR - they are approximations. There 
> are some particular situations where a 1:1 VSWR produces more loss than 
> with a higher VSWR. here's an example:
> Take 15ft of RG213 with a load of 100+j100. At  3.8 MHz the loss with 
> this 4.3:1 VSWR is 0.025dB, whereas the matched loss is over twice this 
> at 0.055dB. I know these are ridiculously small losses, but I'm just 
> illustrating the fallacy of thinking you can add a fixed "extra loss" 
> figure for some particular VSWR value.
> 73,
> Steve G3TXQ
> Dr. Gerald N. Johnson wrote:
>> Are you sure? Using data and formulae in the 1994 ARRL Antenna Book, I
>> see 100' of RG213 has 0.6 dB loss at 4 MHz when matched, and 1.066 dB
>> with a 3.6:1 SWR. 1" spaced window line has 0.027 dB (had to stretch the
>> loss chart by a factor of ten for that line) per 100' matched and 0.41
>> dB loss with the SWR of 32:1.
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