Bob, KB8TL wrote:
"Anyone have any thoughts on why this might not work?"

I`ve worked in several medium wave broadcast stations which used buried
coax to feed the towers. No problems..

I worked in a shortwave broadcast plant where we needed a 100 KW dummy
load. So we constructed a parallel wire 600-ohm line only about 2 feet
above the earth using Copperweld wires a few hundred feet long. It could
boil the dew on the groud and bring earth worms to the surface. It also
did a great job of dissipating the 100 KW.

Anytime parallel line such as twinlead or ladderline approaches ordinary
earth, loss soars. Direct burial is impractical even inside fairly large
conduit. Use one or two lengths of waterproof coax as buried line.

Best regards, Richard Harrison, KB5WZI

Could you not create low loss "coax" by using concentric pipes?
Might be easier than all this hacking around..

That, or run heliax in the buried section, and convert to balanced in a
little box on the other end.

"Dave VanHorn" wrote in message
...

Could you not create low loss "coax" by using concentric pipes?
Might be easier than all this hacking around..

They call that hard line, as in Heliax etc.

W4OP

And I thought it were only Black pudding that came from Bury...

Richard Harrison wrote:
Anytime parallel line such as twinlead or ladderline approaches ordinary
earth, loss soars. Direct burial is impractical even inside fairly large
conduit. Use one or two lengths of waterproof coax as buried line.

A ham I know uses parallel runs of buried RG62 as a compromise.
That gives him a characteristic impedance of 186 ohms for his 30
foot underground section. It was interesting to model that setup
using MicroSmith.
--
73, Cecil http://www.qsl.net/w5dxp


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Cecil, W5DXP wrote:
"A ham I knpe uses parallel runs of RG 62 as a compromise. That gives
him a characteristic impedance of 186 ohms for his 30 foot underground
section."

Yes. It`s balanced to ground and has twice the characteristic impedance
of a single run of coax. In the case of twin runs of RG 82, that is
twice a value of 93 ohms, or 186 ohms, center conductor to center
conductor.

I recall analog microwave radios which had their baseband signals wired
with twin runs for each direction of transmission like that to obtain a
shielded and balanced baseband system. It must have been good for the
coax business and it made for a quiet radio too.

Best regards, Richard Harrison, KB5WZI