What does this statement really mean Jim? You say to stay away from copper
coated aluminum, but then say there is no increase in loss at 1MHz.
Please clarify.
73
Jim W7RY
Q: What about copper coated steel and copper coated aluminum?
A: For frequencies below 10 MHz, avoid copper-coated steel. At higher
frequencies, skin
effect takes over, and all the current is in the thin coating, but at lower
frequencies, the
steel increases the resistance (and the loss). Measurements of LMR400, which
has a
copper coated aluminum center conductor, show no increased loss due to the
higher
resistance of the aluminum, even as low as 1 MHz.
--------------------------------------------------
From: "Jim Brown" <jim@audiosystemsgroup.com>
Sent: Friday, July 22, 2011 11:54 AM
To: <towertalk@contesting.com>
Subject: Re: [TowerTalk] DX Engineering DXE400MAX Cable?
> On 7/22/2011 5:28 AM, Mark Robinson wrote:
>> I would call DX Engineering and ask them who makes their DXE cable for
>> them
>> and how it compares to the Davis equivalent.
>
> YES. Also, there is NO good reason for a foil shield at HF, and several
> authorities have noted long term aging issues with contact between the
> braid and foil. W2VJN noted this in the latest edition of his excellent
> book on Managing Interstation Interference with respect to the stability
> of stubs made with LMR400.
>
> I suggest that you study my tutorial on Coax and Stubs.
>
> http://audiosystemsgroup.com/Coax-Stubs.pdf
>
> IMO, the Davis stuff hits the sweet spot for HF operation, based on
> performance specs and cost.
>
> 73, Jim K9YC
> _______________________________________________
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