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

[Bob McGraw - K4TAX]

I totally agree.  Your measurements are "real world" and correct!

I've used ladder line of various types for years and very successfully. 
Even at one time I used it, actually the open wire version,  to feed the 144 
MHz EME array.  Even in a matched condition, it beats the pants off of coax 
line in terms of lower loss and higher power handling ability.

It is as Will Rodgers once said;  "Its not what folks know that concerns me, 
it's what folks know that isn't correct that gives me concerns".   There is 
a LOT of incorrect information, published, written and said about these 
lines that IS NOT correct.

Thanks, I'm with you on this one!

73
Bob, K4TAX


----- Original Message ----- 
From: "Steve Hunt" <steve at karinya.net>
To: "Discussion of Ten-Tec Equipment" <tentec at contesting.com>
Sent: Saturday, August 03, 2013 9:50 AM
Subject: Re: [TenTec] OT: Openwire/Window Line and Bad Wx


> 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
>>
>
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