[TenTec] OT: Openwire/Window Line and Bad Wx

[Steve Hunt]

Bob,

Perhaps I had better explain clearly why I am carrying out these 
ladderline tests.

I believe that the "wet" ladderline losses reported by Wes Stewart, and 
those predicted by at least two of the popular on-line calculators, are 
sufficiently high that some folk could be put off using the stuff. It 
seemed to me important to understand: how Stewart arrived at his 
figures; why Stewart's figures are so different from the ARRL 
measurements; what sort of losses can be expected in practice.

That's all :)

73,
Steve G3TXQ





On 03/08/2013 14:37, Bob McGraw - K4TAX wrote:
> Steve et al:
>
> I'm not saying that loss does or does not change with the vinyl type 
> window line between wet and dry.  I do agree with your results in that 
> loss does increase with a wet line as opposed to a dry line.  I also 
> agree that loss is greater per unit at 28 MHz vs. the same length of 
> line at 1.8 MHz or 3.8 MHz regardless if the line is wet or dry.
>
> My point, with today's receivers, in most all cases the atmospheric 
> noise and man made noise will mask any receiver internal noise and 
> will easily overtake any loss in the transmission line.  However, the 
> loss in the transmission line will affect the NF of the receiver, 
> which on HF is of little significance.   In many cases, we worry about 
> 2 or 3 dB loss in the transmission line but run the attenuator of 10 
> dB to 20 dB at the input of the receiver.  Now on transmit, that point 
> makes a different in the power arriving at the antenna.  Again, 
> typically less than 1 S unit on the other end.  To that point, most of 
> the time I run the Argonaut VI at 10 watts and can work about any 
> station I hear, regardless of line loss.
>
> True open wire line, by definition, is two conductors supported only 
> at the source end and the termination end, drawn taught, and without 
> any spacers. This of course is a real challenge to make work reliably 
> in practice unless one uses large conductors and spaced at 6" to 18" 
> and used at lower frequencies and typically with very high power in 
> the near megawatt range. We used this feed line approach in some of 
> the commercial SW stations to which I attended.  Some of these feed 
> lines were each several thousand feet in length.  All of this is far 
> beyond the scope of most ham installations.
>
> I would like to see more data on dry line vs. wet line from natural 
> cause as opposed to "wetted" line.  I use the vinyl covered line with 
> 66% of the  web spacers removed.  {Remove 2, leave 1, remove 2, leave 
> 1.} I see little change from wet to dry on HF.
>
>
> 73
> Bob, K4TAX
>