75 ohm coax

[Rick Dwight]

If your 75 ohm coax has a steel/copper coated center conductor, be sure to test it for loss on
the lowest frequency band you will use.  I experimented with a steel core 160 meter
antenna and found it had some additional loss and probably due to the inductance
it could be shorter for resonance (10 % perhaps ??) so I abandoned the idea.  Never noticed the effect on higher frequencies.

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[Elecraft mailing list]

I have been using Commscope F660BEF for years for both receive lines and
transmit coax for my 80M 4-sq using F-connectors. The other year I had a
100' piece of RG6 that had a solid copper center conductor and a copper
braid. Compared that to the F660BEF on 1.8 and 3.5 for loss at 100'. I did
not see any difference in power loss. I guess the F660BEF has enough copper
plate to keep losses low on the low bands. Or maybe I just had a bad piece
of copper RG6?
N2TK, Tony

-----Original Message-----
From: [hidden email] <[hidden email]> On
Behalf Of Frederick Dwight
Sent: Friday, April 3, 2020 2:09 AM
To: [hidden email]
Subject: [Elecraft] 75 ohm coax

If your 75 ohm coax has a steel/copper coated center conductor, be sure to
test it for loss on the lowest frequency band you will use.  I experimented
with a steel core 160 meter antenna and found it had some additional loss
and probably due to the inductance it could be shorter for resonance (10 %
perhaps ??) so I abandoned the idea.  Never noticed the effect on higher
frequencies.

Sent from Mail for Windows 10

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[donovanf]

Hi Tony,


Reasonable coaxial cable loss isn't an issue on the low bands unless
you're using an inefficient receiving antenna (e.g. small loop, BOG, or
high impedance short verticals). Most inefficient receiving antennas
use a remotely powered preamp at -- or very near -- the feed point so
even in those cases feed line loss isn't an issue on the low bands


73
Frank
W3LPL

----- Original Message -----

From: "N2TK via Elecraft" <[hidden email]>
To: "Frederick Dwight" <[hidden email]>, [hidden email]
Sent: Friday, April 3, 2020 5:31:45 PM
Subject: Re: [Elecraft] 75 ohm coax

I have been using Commscope F660BEF for years for both receive lines and
transmit coax for my 80M 4-sq using F-connectors. The other year I had a
100' piece of RG6 that had a solid copper center conductor and a copper
braid. Compared that to the F660BEF on 1.8 and 3.5 for loss at 100'. I did
not see any difference in power loss. I guess the F660BEF has enough copper
plate to keep losses low on the low bands. Or maybe I just had a bad piece
of copper RG6?
N2TK, Tony

-----Original Message-----
From: [hidden email] <[hidden email]> On
Behalf Of Frederick Dwight
Sent: Friday, April 3, 2020 2:09 AM
To: [hidden email]
Subject: [Elecraft] 75 ohm coax

If your 75 ohm coax has a steel/copper coated center conductor, be sure to
test it for loss on the lowest frequency band you will use. I experimented
with a steel core 160 meter antenna and found it had some additional loss
and probably due to the inductance it could be shorter for resonance (10 %
perhaps ??) so I abandoned the idea. Never noticed the effect on higher
frequencies.

Sent from Mail for Windows 10

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[Jim Brown-10]

On 4/3/2020 10:31 AM, N2TK via Elecraft wrote:
> I have been using Commscope F660BEF for years for both receive lines and
> transmit coax for my 80M 4-sq using F-connectors.

This is very nice cable -- flooded with a gel that varmints don't like,
very smooth jacket pulls very easily. It's what DX Eng was selling last
I looked. I'm using a lot of it for RX antennas, all the way up to UHF
TV antennas.

73, Jim K9YC


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