Topband: 1000 feet 5/8" hardline or 600ohm True Ladder line.

[Carl]

----- Original Message ----- 
From: "Jim Brown" <jim at audiosystemsgroup.com>
To: <topband at contesting.com>
Sent: Tuesday, April 29, 2014 2:28 PM
Subject: Re: Topband: 1000 feet 5/8" hardline or 600ohm True Ladder line.


> On 4/29/2014 10:08 AM, Richard (Rick) Karlquist wrote:
>> The ARRL Antenna Handbook shows about 0.4 dB for 420
>> feet of 75 ohm 1/2 inch hardline.
>
> I suspect they are talking about 75 ohm heliax, not the typical CATV hard 
> line. The CATV hard line I've seen has an Al shield, so I would expect 
> loss to be a bit greater than heliax, which has a much heavier copper 
> shield.
>
>> Paralleling two
>> runs of line does not decrease the insertion loss.
>
> That depends. Given the same source and load Z as with the single run, it 
> does decrease the loss, because the current divides between the two lines. 
> The condition that does not reduce the loss is the use of two runs of coax 
> wired in series to raise their impedance, so that the center conductors 
> are parallel wire line.
>
> 73, Jim K9YC


1/2" CATV hardline is about .085 dB/100' at 2 MHz and increasing to a hair 
under .4dB at 30 MHz.

The 3/4" chart is well below .1 dB at 2 mHz and doesnt show on the chart 
until 5MHz at .11dB/100' and .26dB at 30 MHz.

Carl
KM1H