[AMRadio] Ground(Or Lack Of)?


Bob Macklin macklinbob at msn.com
Wed Feb 16 21:40:21 EST 2005


Thanks to everyone for their comments on this subject.

My apartment is 20' by 20'. A RETIREMENT CLOSET! My desk with the station is
in the SE corner of the livingroom. That's where the center of the antenna
is. The antenna is on the wall about 6" below the ceiling. One leg goes west
almost 20' then turns north for the remainder. The other leg starts in the
same corner and goes north about 18' then turns west for the remainder.

The antenna tuner will be on a shelf directly below the feedpoint. There
will be no transmission line. The antenna will connect directly to the
balanced line terminals on the back of the matchbox.

There will be RF in the shack. I have put the DX-60 on the single leg and
have barely noticable heringbone on some TV channels. And I have no TVI
supession on the TV yet. I am not going to mess with it until I get the full
antenna/matchbox system working.

What ground there is will only be for safety purposes. I don't think the OLD
LADIES can see well enough to see the heringbone.

Thanks again for you comments.

Bob Macklin
K5MYJ/7
Seattle, Wa.

"REAL RADIOS GLOW IN THE DARK"

----- Original Message ----- 
From: "Jim candela" <jcandela at prodigy.net>
To: "Discussion of AM Radio" <amradio at mailman.qth.net>; "Bob Macklin"
<macklinbob at msn.com>
Cc: "GlowBugs" <glowbugs at piobaire.mines.uidaho.edu>
Sent: Wednesday, February 16, 2005 6:17 PM
Subject: RE: [AMRadio] Ground(Or Lack Of)?


>
>
>    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"
> > ______________________________________________________________
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> >
>
>
>
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