----- Original Message -----
From: "Tom W8JI" <w8ji@w8ji.com>
To: "TopBand" <topband@contesting.com>
Sent: Thursday, June 21, 2012 5:03 PM
Subject: Re: Topband: Chokes for Beverages
>> The subject was LMR-400 which, of course, is not flooded and uses a
>> tinned
>> copper weave over aluminum foil.
>
> Sorry. My mistake.
Its often hard to kep track the way a few go suddenly tangential.
>
> I thought the subject was receiving cables, related to Beverages, and
> common
> mode noise, and that somehow a parallel was drawn to a stb measurement on
> LMR400, which was a "needles in a haystack" change anyway in the
> application
> of stubs when compared to antenna-to-antenna leakage paths.
Thats a long sentence but yeah, thats where we started from yesterday. Ive
been guilty of taking a side trip at times also (-;
>
> There is some real questionable information on stubs, and it doesn't have
> much to do with receiving transmission line behavior anyway.
>
>> If they decided to go with flooding I might even use it outdoors.
>>
>> Of equal concern is the variety of crimp connector vendors as well as off
>> brand 400 "type" cable.
>
> I don't hesitate to use "LMR400" types here, provided the cable is well
> constructed. Some cables are pretty thin copper cladding on the center,
> which can significantly impact loss on lower bands as current moves out of
> the copper and into the core. Small CCS center cables can have much higher
> loss than expected on low frequencies, so far as transmitting applications
> go.
>
> 73 Tom
I thought that the cladding still carried most all of the current since the
RF resistance of the core forced it to. Even the very thin copper on RG-6
steel core loses very little signal at 160 which is where it starts to dip
with about .15dB/100'. Im sure its much higher at 600M and on down but
outside noise is very high down there on a Beverage to be noticable. Its
also still a bit better than 8X; and CATV 11 is still straightlining at 1
MHz.
Carl
KM1H
>
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