Hello Bob,
A big concern of mine would be the RF. Your 20X20 shack, is it in
a retirerment home? If it is, are there alot of people with electronic
medical devises.
I was told at a seminar, that the pace-makers, varges nerve
stimulatars, and automatic drug dispensers are highly subseptible to
RF. I wouldn't want to get blamed for killing some of these old people
with a QSO!
Tnx,
Tony
>From: "Bob Macklin" <[EMAIL PROTECTED]>
>Reply-To: Discussion of AM Radio <[email protected]>
>To: "Jim candela" <[EMAIL PROTECTED]>,"Discussion of AM Radio"
<[email protected]>
>CC: GlowBugs <[EMAIL PROTECTED]>
>Subject: Re: [AMRadio] Ground(Or Lack Of)?
>Date: Wed, 16 Feb 2005 18:40:21 -0800
>
>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" <[EMAIL PROTECTED]>
>To: "Discussion of AM Radio" <[email protected]>; "Bob Macklin"
><[EMAIL PROTECTED]>
>Cc: "GlowBugs" <[EMAIL PROTECTED]>
>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: [EMAIL PROTECTED]
> > [mailto:[EMAIL PROTECTED] Behalf Of
[EMAIL PROTECTED]
> > 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 <[EMAIL PROTECTED]>:
> >
> > > 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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