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Old July 28th 08, 07:55 PM posted to rec.radio.amateur.antenna
826[_2_] 826[_2_] is offline
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First recorded activity by RadioBanter: Jul 2008
Posts: 5
Default Vertical problem

Hi,
Here is some more info. The depth of the coax is 6". Its length is 75 foot
of RG-213. The ground here is below sea level (3 ft). It was reclaimed from
salt water by wind driven pumps in the 14th and 15th century. The
conductivity of the ground is great for antennas. But not sure about buried
feed lines.
I tested the antenna with the MFP-259 and 6 ft of cable on the ground. Yes
the first thing I checked was if the reading changed if I backed off from
the instrument and antenna.
I have tried buried coax one other time with a 2m vertical and thought the
coax was bad because it was used before. It also gave bad reading but can
remember the details. Do remember running another peace of coax back to the
shack overhead and everything was OK.
Now I wondering if it is something to do with the installation. The coax is
new and inside of a garden hose for protection. I did check the hose to make
sure it was dry before it was used.
I know that the antenna is adjusted correctly and have taken an FT-817 and
SWR meter to the antenna and it also indicated good readings.
Now something tells me not to tune the antenna with the instruments locate
in the shack because it will not be curing the problem. It will just hid it
until I start running some power. Then I would think something would start
to get hot in the field. Like the traps.
Because the antenna no longer wants my power because its no longer tuned to
the ham bands.
Regards
Vern

"Ed" wrote in message
92.196...
...
About as well as it flows up the center conductor, possibly. You
don't think that just because the cable is buried that RF flow on the
shield conductor is prevented, do you?

Ed


I sure can imagine one heck of a "capacitive load" on that outer
conductor to ground! What, thousands/tens-of-thousands of pf?

Regards,
JS



I was not aware of the depth, length, and other specifics of the
buried coax installation as I jumped into the thread a bit late. Sorry.
Here where I'm located we have nothing but sand, which doesn't really
provide much of a ground. I forget other people have real dirt! :^)

Ed