Question about grounding
Fred Cole
connected through my MFJ Versa Tuner II. From what I've noticed, I can
transmit ssb on 10M with one antenna but I don't seem to be able to
with the other antenna.
One antenna is an indoor 2m ( I know I shouldn't even consider using
it for TX ) the other is a longwire. It's the two meter antenna that
works for ssb. When I use the longwire on 10M I hear a screetch like
feedback when I use higher than about 10 watts on CW. Also, when using
the longwire, I can't even get the alc meter to even twitch, no matter
how high or low I turn the mic gain.
Is this problem caused by a lack of a ground? Or is it just the
operator? Since the power supply has a 3 wire plug, the connector to
the rig is 3 wire, and the ground lug on the tuner is connected to the
ground lug on the rig, doesn't that mean that they are already
grounded? Do I need a ground in addition to the apparent house ground?
Since I live in a trailer park, with no nearby trees, I figure that
the longwire is my best bet, unless someone else can give me a
suggestion on homebrew antennas, I heard about an underground type but
haven't found anymore info on them.
Tnx
Fred Cole - N2NRV
Bubba
10 meters is the first band that will exhibit those problems.
you should ground your rig to groundrods outside the shack.
The electrical ground (3rd wire) is not a good RF ground.
Get a copper 8' stake from ratshack at the minimum, and drive it in the
ground just outside your window. Use as big a wire as you can get -- copper
braid or 1'' copper strap is best, but #10 house wire will work in a short
run and connect that to the transmitter AND the tuner's ground
The 2meter ant should be just about useless at 10 meters unless you want
local cb type service.
As far as underground -- the rule of thumb for antennas is "bigger and
higher is better".
Try a vertical -- should work fine in your situation -- you say it is a long
wire, but that really is a multiple wave length antenna so for 10 meters
your wire would need to be 60-100 feet long. What you probably have is a
random wire.
Get yourself a vertical ant -- use the metal roof of your trailer for a
ground plane and it should: A) work quite well, and B) fix your RFI
problems. I lived in an apartment that had a metal roof -- put a vertical
in the middle of it and worked the world.
cheers
Fred Cole <emer...@twcny.rr.com> wrote in message
news:20000222...@KIRK.twcny.rr.com...
Mark Keith
>
> I have an IC-701 with the IC-701PS power supply. My two antennas are
> connected through my MFJ Versa Tuner II. From what I've noticed, I can
> transmit ssb on 10M with one antenna but I don't seem to be able to
> with the other antenna.
>
> One antenna is an indoor 2m ( I know I shouldn't even consider using
> it for TX ) the other is a longwire. It's the two meter antenna that
> works for ssb. When I use the longwire on 10M I hear a screetch like
> feedback when I use higher than about 10 watts on CW. Also, when using
> the longwire, I can't even get the alc meter to even twitch, no matter
> how high or low I turn the mic gain.
>
> Is this problem caused by a lack of a ground? Or is it just the
> operator? Since the power supply has a 3 wire plug, the connector to
> the rig is 3 wire, and the ground lug on the tuner is connected to the
> ground lug on the rig, doesn't that mean that they are already
> grounded? Do I need a ground in addition to the apparent house ground?
You need a complete antenna. The longwire you are using requires an rf
ground to function correctly. I would put up a dipole, vertical,
whatever that is complete and has it's own rf ground system. A dipole is
complete in itself and needs no ground. A vertical needs a ground radial
set, or at the least a connection to a ground rod at the base of the
vertical. With the longwire you are using , you are feeding the whole
thing from the tuner on, so you have loads of rf in the shack. This is
the antennas fault, not really from a lack of grounding at the rig, but
a lack of an rf ground for the antenna. You really don't want the rf
ground for the antenna to be at the shack. You want it at the antenna.
So switch to a dipole, or a vertical with grounding, and your problems
should go away. With the right antenna, a ground at the shack is really
unnecessary as far as rf grounding, but you could use one if you feel
compelled. I don't use a shack ground anymore. And have no rf problems
on any band. Mainly because rf in the shack is an antenna/feedline
problem, not from lack of grounding. Grounding is a "bandaid" commonly
used to try to fix other problems. One example is camping and running
portable, I've never once used a ground ever, and have never ever had rf
problems portable, because I use complete antennas. Usually dipoles
strung from trees. MK
Fred Cole
>>>>>>>>>>>>>>>>>> Original Message <<<<<<<<<<<<<<<<<<
On 2/24/00, 4:11:32 PM, Mark Keith <nm...@wt.net> wrote regarding Re:
Question about grounding:
> So switch to a dipole, or a vertical with grounding, and your problems
> should go away. With the right antenna, a ground at the shack is
really
> unnecessary as far as rf grounding, but you could use one if you feel
> compelled. I don't use a shack ground anymore. And have no rf problems
> on any band. Mainly because rf in the shack is an antenna/feedline
> problem, not from lack of grounding. Grounding is a "bandaid" commonly
> used to try to fix other problems. One example is camping and running
> portable, I've never once used a ground ever, and have never ever had
rf
> problems portable, because I use complete antennas. Usually dipoles
> strung from trees. MK
I do have an antenna that can be used but it would need to be strung
from a tree. The problem is that the nearest tree is on the other end
of the trailer park from me. I do have an aluminum mast attached to
the trailer, if I use that I can make a sloping dipole and simply deal
with it becoming directional, or the neighbor mowing over one end of
it during the summer. My only other option of mounting material is
hanging a dipole from 2x4's in the middle of my yard. Which is also
why I was looking for information on underground or on ground
antennas. Making the antenna is the easy part, it's putting them up in
the air that is difficult. I'm going more for ability to hide rather
than coverage.
Fred - n2nrv
Mark Keith
>
> >>>>>>>>>>>>>>>>>> Original Message <<<<<<<<<<<<<<<<<<
>
> I do have an antenna that can be used but it would need to be strung
> from a tree. The problem is that the nearest tree is on the other end
> of the trailer park from me. I do have an aluminum mast attached to
> the trailer, if I use that I can make a sloping dipole and simply deal
> with it becoming directional, or the neighbor mowing over one end of
> it during the summer. My only other option of mounting material is
> hanging a dipole from 2x4's in the middle of my yard. Which is also
> why I was looking for information on underground or on ground
> antennas. Making the antenna is the easy part, it's putting them up in
> the air that is difficult. I'm going more for ability to hide rather
> than coverage.
>
> Fred - n2nrv
I'm wondering if you couldn't mount the apex of a dipole on the mast and
run eash leg way from it in different directions, instead of a sloping
dipole. Can be about any angle as long as not less than 90 degrees. I've
used alot of inv vees that were a vee on their side, as well as to the
ground. Doesn't hurt them much, and still pretty omnidirectional. Or on
the low bands anyway. Not sure which band/s you want , so length would
vary. A good vertical could work out ok, but would tend to favor dx over
regional stuff. A ground mounted butternut is fairly good, even with
fairly limited ground radials and would work all bands. You mention 10m,
a good cb antenna on your mast would probably do about as good as
anything for that band. Say a 5/8 GP or a 1/2 wave, or 1/4 GP Can be
easily homebrewed from scrap tubing. MK
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