[AMRadio] Ground(Or Lack Of)?


Jim candela jcandela at prodigy.net
Wed Feb 16 21:17:15 EST 2005



   Bob,

    I do something that is a bit out of the ordinary, and on occasion has
helped. My shack usually runs off a 10 outlet power strip with three prong
120 v 15 amp jacks. I have found that making a common mode choke for the
three wires in the power strip helps keep my RF from conducting into the AC
power in my home. I do this with a suitable ferrite rod similar to a G-G
linear filament choke. This gives me a good and safe 60 hertz ground for my
equipment, and discourages the Rf from going into your power line as a
common mode signal. I would then direct any RF floating on my equipment
chassis's to a close-by ground rod, and use 1" wide braid.

    In your case, you could try the 1/4 wave ground wire concept tied to
your rig (or MFJ equivalent), and use the common mode choke on your shack
power strip. I'm not too sure how much this might help since the proximity
of the antenna to all sorts of building wiring (door bell, phone wires,
cat-5, catv, ac power, gas pipes, furnace ducts, plumbing, re-bar, I-Beams,
etc) will most likely unbalance an indoor dipole antenna. You might try to
force the balance with a current balun as well, and maybe change the lengths
a little due to varying detuning on each end.

    Another thought (from Dr. Evil) would be to go around your apartment
with a impedance bridge, and look at the impedance between any two points,
like the CATV shield, and the furnace ducts. You might find a combination
that is easily tuned to 50 ohms resistive on a frequency you want to operate
on. I know this sounds crazy, but realize that every FCC part 15 device in
the complex is likely to go nuts with your transmitter on anyway... I can
see the whole complex blinking on and off to your CW CQ...Aliens on another
planet might see your CW from the visual blinking! If you cannot get the RF
out of the wiring, heck use the wiring for your antenna, and operate VERY
infrequently. :-)

Regards,
Jim Candela
WD5JKO


-----Original Message-----
From: amradio-bounces at mailman.qth.net
[mailto:amradio-bounces at mailman.qth.net]On Behalf Of k0ng at inebraska.com
Sent: Tuesday, February 15, 2005 6:42 PM
To: Discussion of AM Radio; Bob Macklin
Cc: AM Radio; GlowBugs
Subject: Re: [AMRadio] Ground(Or Lack Of)?



Bob: Dont expect any problem with your dipole (unless you are right under
it, then things might get hot). A dipole does not need any ground to
operate.
The "3rd wire" should only be used as a safety line to the radio chassis.
It would be best if you checked the 3rd wire continuity all the way back to
the building entrance ground but I realize this is probably impractical.

Good Luck,  DE Charlie,  K0NG  ..

Quoting Bob Macklin <macklinbob at msn.com>:

> Back to my 4th floor apartment problem. This building has plastic
> plumbing(which seems to leak at tleat once a month). This morning I pulled
> the plate off one of the wall plugs. The building has plastic conduit
also.
>
> So the only ground is the third wire and who knows where or how it runs.
>
> The antenna will be made to a full 40M dipole. What kind of problems
should
> I expect from the crappy ground?
>
> Bob Macklin
> K5MYJ/7
> Seattle, Wa.
>
> "REAL RADIOS GLOW IN THE DARK"
> ______________________________________________________________
> AMRadio mailing list
> Home: http://mailman.qth.net/mailman/listinfo/amradio
> Help: http://mailman.qth.net/mmfaq.html
> Post: mailto:AMRadio at mailman.qth.net
>



______________________________________________________________
AMRadio mailing list
Home: http://mailman.qth.net/mailman/listinfo/amradio
Help: http://mailman.qth.net/mmfaq.html
Post: mailto:AMRadio at mailman.qth.net
--
No virus found in this incoming message.
Checked by AVG Anti-Virus.
Version: 7.0.300 / Virus Database: 265.8.8 - Release Date: 2/14/2005

--
No virus found in this outgoing message.
Checked by AVG Anti-Virus.
Version: 7.0.300 / Virus Database: 265.8.8 - Release Date: 2/14/2005




More information about the AMRadio mailing list

This page last updated 21 Oct 2017.