[TowerTalk] Open Wire Line

[donald.s.tucker@exgate.tek.com]

Spreader source?

Don W7WLL

> -----Original Message-----
> From:	w8ji.tom [SMTP:w8ji.tom@MCIONE.com]
> Sent:	Thursday, October 22, 1998 10:13 AM
> To:	towertalk@contesting.com; topband@contesting.com
> Subject:	[TowerTalk] Open Wire Line
> 
> 
> This might be of general interest to people with long feedlines.
> 
> I'm installing a very tall tower for an expanded 160 system 1400 feet back
> from my shack. I needed a low-loss feeder to get RF back there, so I
> decided to pull an open wire line made from number 8 copper wire spaced
> just under three inches. That makes it about 450 ohms.
> 
> My matching transformers using 61 Ferrite Material (9:1 balanced to
> balanced) and baluns (1:1 choke baluns) have a single unit loss of .17 dB
> at 15 MHz, immeasurable loss at 2.5 MHz. They are designed to handle a
> 10:1
> VSWR at 2 kilowatts CCS. Applying 2000 watts CCS for 1/2 hour, they remain
> stone cold.
> 
> The total measured loss of this system really shocked me. I knew open wire
> line was good, but not this good. Matched power loss on 2.5 MHz was 0.33
> dB, including transformers! 15 MHz loss was only 1.3 dB. That means
> feedline loss was about 0.3 dB on 2.5 MHz and just under 1 dB at 15 MHz.
> 
> Apparently there is a lot to be said for using true open wire line. Loss
> in
> 1400 feet of line is about the same as loss in 100 feet of RG-213/U. Not
> only that, I can run my tower light power through the same wires. 
> 
> 73 Tom
> 
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