the losses are fairly significant alright.
I think these are sort of opposite ends of the loss spectrum though.
that said, I did see some specs from a website not long ago that showed
losses of around 1DB at 30MHZ with LMR400 and beldon 9913.
there are so many different kinds of coax these days though...there are so
many different varieties of 213, RG8, lmr400 and 9913 as well as all the
different kinds inbetween. Each one of the major types of coax have at
least 5 varieties to choose from within their own categories.
There is flex, various types of foam dialectric, double shielded, heliax,
solid center and multi-strand center conducters and on and on.
They all have slightly different loss ratings bassed on frequency and
length.
a rule of thumb, just like nearly anything else in this world, is the more
you spend, the better quality and performance you will get.
72 cents a foot will get you a feedline that will certainly work, but $2.65
a foot will get you something that will be far less lossy and will handle
more power and so on.
go to $5 a foot and it'll be about as good as your going to get it.
that said, the difference between a coax that has a loss rating of 1.5DB at
100 feet at 30MHZ, and a coax that has a loss rating of 2.2DB at 100 feet at
30MHZ could be quite significant as far as cost goes. And, not very
significant as far as performance goes...you really wouldn't notice the
difference...and the lossier stuff may well be half the price or better.
obviously 5.5DB loss at those specs is something to steer clear from, but 1
or 2 db of difference won't be observable without test equipment.
where you really start to see major losses is in the VHF and UHF spectrum.
73
Colin, V A6BKX
----- Original Message -----
From: "Howard Kaufman" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Tuesday, July 20, 2010 4:38 AM
Subject: Fw: Need some input on HF wire antennas for the Michigan house
>I forwarded the feedline comparison page to a friend of mine. I have no
> idea if it is speech friendly, but here are the surprising results of his
> test data.
>
> I put the first Wireman ladderline in. 100 feet. SWR 10 to 1. Power 100
>> watts. Frequency 30 megahertz. Loss is 1.33 dB. 74 watts is still
>> radiated.
>>
>> Then I put in Belden RG 58. Same parameters otherwise. Loss is 5.5 dB.
>> 29
>> watts radiated on 10 meters.
>>
>> Is coax that more convenient than ladder line???
>>
>> Thanks for the reference.
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