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

[Bob McGraw - K4TAX]

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


----- Original Message ----- 
From: "Steve Hunt" <steve at karinya.net>
To: "Discussion of Ten-Tec Equipment" <tentec at contesting.com>
Cc: "Phil Sussman" <psussman at pactor.com>; "Bob McGraw - K4TAX" 
<RMcGraw at Blomand.net>
Sent: Saturday, August 03, 2013 8:01 AM
Subject: Re: [TenTec] OT: Openwire/Window Line and Bad Wx


> We're talking here about reported changes in loss that - if true - would 
> be equivalent to a 5dB change between dry and wet on a 100ft of ladderline 
> feeding a doublet on 10m.
>
> Are you folks trying to tell me that 5dB makes "little to no difference"?
>
> Steve G3TXQ
>
>
>
>
> On 03/08/2013 13:27, Phil Sussman wrote:
>> Bob is right! In the end, propagation will dictate. External
>> conditions have more of an effect than the subtle differences
>> over which we have control.
>>
>> Sure we can increase efficiency, yet the results are subtle.
>> It all depends upon whether the band is open, eh?
>>
>> Well said, Bob!
>>
>> 73 de Phil - N8PS
>>
>> ------
>>
>> Quoting Bob McGraw - K4TAX <RMcGraw at Blomand.net>:
>>
>>> As I said in my closing remark in an earlier post:
>>>
>>> "I realize that we'd like to eak out every dB we can, but in the end, it
>>> makes little to no difference on HF."
>>>
>>> If one can match the load, using what ever means and equipment, then 
>>> energy will be transferred.  On receiving, atomospheric and man made 
>>> noise will overtake any losses in the antenna system and will over ride 
>>> most all receiver noise.
>>>
>>> 73
>>> Bob, K4TAX
>>>
>>
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