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
>>
> _______________________________________________
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>
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