Joel,
I had an experience at Field Day in OKC concerning openwire that completely
surprised me.
I have always run openwire as you say, "in the clear", but at FD something
funny happened which had curious results.
Due to the heat (over 100 deg. F), we set up in an air conditioned volunteer
fire department which had heavy metal doors.
We ran all coax and the openwire from our vertical dipole and our 135 ft.
doublet through the open door, into the shack.
Both openwire fed antennas were pre-tuned before the FD started and charts
were made with matchbox pre-sets.
At night, somebody closed the door as best he could, to keep the bugs out.
The coax's were laying on the ground, stacked vertically on top of each
other and squeezed by the door, but he shoved the openwire up over the metal
door, pushed them towards the side and closed the door on them.
I was running the CW station on the doublet at the time, but did not notice
the door getting closed AND it did not cause any change to the matchbox
settings, nor any apparent loss in ability to work at least one station per
minute.
I would have expected it to basically short the two wires of the Wireman
Window Line, but apparently nothing changed.
I have not made any attempt to repeat that kind of circumstance but it
certainly made me wonder.
In the past 30 years I've built all kinds of contraptions to enable me to
get the openwire in through metal window frames. Maybe I should have just
closed the window on the line and used it!
73
Rick, DJ0IP
P.S. I think it was one of the boys visiting us from Texas who closed the
door on the window line!
-----Original Message-----
From: TenTec [mailto:tentec-bounces@contesting.com] On Behalf Of Joel Hallas
Sent: Wednesday, August 14, 2013 4:15 AM
To: 'Discussion of Ten-Tec Equipment'
Cc: k9yc@arrl.net
Subject: Re: [TenTec] Wet ladderline
Bob,
Good observations, and I have also seen European HF broadcast curtain arrays
using our friends, the open wire line. It works as well today as it did in
1930.
The key thing about such line is that, unlike coax, the fields are not just
"between" the conductors, but surround them at 2-3 times the spacing. Put
lossy stuff (such as terra firma) within that region and you warm worms.
Both our ARRL measurements (2009) and Steve Hunt's recent data confirm high
attenuation (up to 10 dB/ 100 ft, as I recall) of window (or open wire) line
laying on the ground.
This may come up more at Field Day locations than at other times, but keep
it in mind.
Regards, Joel Hallas, W1ZR
Westport, CT
-----Original Message-----
From: TenTec [mailto:tentec-bounces@contesting.com] On Behalf Of Bwana Bob
Sent: Tuesday, August 13, 2013 10:02 PM
To: Discussion of Ten-Tec Equipment
Cc: k9yc@arrl.net
Subject: Re: [TenTec] Wet ladderline
I like LMR400. We ordered spools of it along with N connectors for the
workplace when we rebuilt our GPS antenna distribution system. We have
preamps built into the antennas and in the splitter, but the coax runs from
the antennas are about 100 ft and at 1.5 GHz, LMR400 works very reliably.
The system we replaced used RG-213, which was marginal. Some hams say that
LMR400 is noisy, and they buy Belden 9913. I think that's an urban myth, and
I hear that water can get into the 9913 because it is mostly air dielectric.
To each his own.
I have to laugh about the idea of burying open wire or window line. The
whole idea of using window or ladder line today is to reduce dielectric
losses by making sure that most of the dielectric between the conductors is
air, so that attenuation under a high SWR will be minimal. Now replace the
air with a lossy dielectric like dirt and see what happens.
In 1991 I found myself in a foreign land. The hotels were in a line on the
beach and a couple of blocks in were several embassies. I amused myself by
walking around spotting antennas. Except for one big log periodic, all of
the embassy rooftops sported dipoles fed with good old
600 ohm ladder line.
73,
Bob WB2VUF
On 8/13/2013 11:41 AM, Mike Bryce wrote:
> You're right, Jim,
>
> I ordered the LMR400 and had a bit of worry about how well the copper
> clad
would hold up to the soldering iron.
>
> seemed to work okay, but that stuff sure is hard to work with.
>
>
> Mike Bryce, WB8VGE
> the heathkit shop
> SunLight energy systems
> J e e p
> o|||||||o
>
>
>
>
>
>
> On Aug 13, 2013, at 3:19 AM, Jim Brown wrote:
>
>> LMR400UF (Ultraflex) has stranded copper center. :LMR400 has copper
>> clad
Al. Two different cables.
>>
>> 73, Jim K9YC
>>
> _______________________________________________
> TenTec mailing list
> TenTec@contesting.com
> http://lists.contesting.com/mailman/listinfo/tentec
>
>
> -----
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