I think you're being overly picky. The 75-ohm cable would be at worst a 1.5:1
mismatch. Probably a fraction of a dB loss at most, particularly with foam type
hard line. If you have a source of good, low-loss 75-ohm coax that will safely
handle the power you intend to run, and which will hold up
On 6/13/2014 12:17 PM, Donald Chester wrote:
I think you're being overly picky. The 75-ohm cable would be at worst a 1.5:1
mismatch. Probably a fraction of a dB loss at most, particularly with foam type
hard line. If you have a source of good, low-loss 75-ohm coax that will safely
handle the
Don,
You bring up some good points. I got a couple of hundred feet of Flooded
Commscope 75 ohm RG-11 type at a good proce. I don't have the part number
handy. I've been very happy with it at 100 watts. I'm thinking of running 500
watts. The center conductor is copper clad steel. I'm concerned
Frank,
That is true but a 1/2 wavelenght at 160 meters is quite long, about 260 feet;
shorter with the velocity factor.
Mike N2MS
- Original Message -
From: donov...@starpower.net
To: topband@contesting.com
Cc: j...@audiosystemsgroup.com
Sent: Fri, 13 Jun 2014 20:01:13 - (UTC)
Ive been using that CATV RG-11 since the late 70's as jumpers to the
hardline from wire antennas, in the house, and as phasing lines for 160 and
80M verticals. Never a hint of heat at 1200W but someone with a 3CX15000
might have a different opinion. Measured loss at 2 MHz was .17dB/100'
For monoband use, use an asynchronous transformer to go to 50 Ohms if you or
the equipment is that fussy.
http://www.k1ttt.net/technote/matching.html
Carl
KM1H
- Original Message -
From: donov...@starpower.net
To: topband@contesting.com
Cc: j...@audiosystemsgroup.com
Sent: Friday,
All,
I'll try out the CATV RG-11 before spending my money on 50 ohm coax.
It will also save me the touble of digging another trench.
Mike N2MS
- Original Message -
From: Carl k...@jeremy.mv.com
To: mstang...@comcast.net, Donald Chester k4...@hotmail.com
Cc: topband@contesting.com
Sent:
This does however, slightly narrow the bandwidth of the antenna if the coax
loss is small because as you move away from the perfect 1/2 wave point the
coax will start to show SWR. For monobanders this usually isn't a problem,
but it may be for some tribanders.
This will also work on all the
You bring up some good points. I got a couple of hundred feet of Flooded
Commscope 75 ohm RG-11 type at a good proce. I don't have the part
number handy. I've been very happy with it at 100 watts. I'm thinking of
running 500 watts. The center conductor is copper clad steel. I'm
concerned about
On 6/13/2014 9:51 PM, Tom W8JI wrote:
The worse case SWR of a 50 ohm system with 75 ohm cable isn't 1.5:1
when normalized to 50 ohms. It is 2.25:1. 1.5*1.5 = 2.25
Wrong. If you're using 75 ohm line, it's a 75 ohm system -- the system
impedance is the line impedance. It's the the match of the
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