[TenTec] SLIGHTLY OT

[Steve Hunt]

Mike,

Yes, it's a very popular "Ham Myth" - not helped by various articles in QST.

TLW is the software supplied by ARRL with the Antenna Book. It 
calculates the losses and impedance transformations for various types of 
feedline, given the load impedance. It typically underestimates losses, 
and I would normally use the VK1OD on-line calculator in preference to 
it, but that doesn't include a model for 600 Ohm line whereas TLW does.

Here are the calculated losses for various types of line - all 110ft 
long and at 1.9MHz - when terminated in 11-j930 Ohms:

TLW, ARRL "generic" 600 Ohm line: 2.6dB
VK1OD, Wireman 551 ladderline : 6dB
VK1OD, Wireman 551 ladderline (wet): 8.2dB

Remember this is all at 160m !!!!

If you'd like to know more, take a look at this review of the QST 
article "The Lure of Ladder Line":
http://vk1od.net/transmissionline/LOLL/

73,
Steve G3TXQ



On 08/04/2011 20:58, Mike Bryce wrote:
> Don't shoot me!
>
> But I always read that open line feed was lossless.
>
> Mike
>
>
> Sent from my iPhone
>
> On Apr 8, 2011, at 3:42 PM, Steve Hunt<steve at karinya.net>  wrote:
>