Hi Bob:
I think you miss-read my e-mail. I do not have any problem with RFI or
RF in any of my equipment with my set up. Computer, Telephone or TV using my
present grounding system. No hot spots.
I was replying to a posting asking for help on RFI in a Pegasus.
The RF in my shack is direct from Antenna Radiation and there is no way
to get rid of that except into a dummy load and not transmit it out of the
antenna. Thanks for your comments. They all make sense.
--
73's
Jack, W7EJJ
----- Original Message -----
From: "Bob & Linda McGraw K4TAX" <RMcGraw@InfoAve.Net>
To: "Jack Malone" <malonej@c2i2.com>
Sent: Sunday, April 22, 2001 3:09 PM
Subject: Re: [TenTec] I'm getting reports of RF in my Pegasus ssb audio.
> Jack:
>
> In response to several inquiries, here's my thoughts on ground.
>
> There's 3 basic types of radio system grounds.
>
> (a) DC ground:
> Best described as a conductor running from the radio to a driven ground
> rod. It is better than nothing in most cases but can be quite
> troublesome due to the length and inductance contained therein.
> Sometimes one is better off with out this system. In many cases the 3rd
> pin on the AC wiring serves this purpose better and thus provides a
> safety ground.
>
> (b) Lightening protection ground:
> Very heavy conductors (I use 1/2" soft copper water pipe) running from
> the base of the tower to several (4 or more) driven grounds (1/2" dia
> copper clad, 8 ft long), preferrably in a 8 ft or greater radius from
> the base of the tower. Also, the house AC mains ground must be
> connected to this system via a #6AWG or larger wire. Failure to do this
> will most surely produce a ground system potential difference,
> especially during a nearby lightening strike, leaving the radio
> connected in between the two grounds. Due to a difference in ground
> potential, most likely damage will occure to the radio.
>
> (c) RF ground:
> A very short, heavy, low inductance conductor running from the radio to
> the lightening protection ground. A 2" wide to 6" wide copper strap is a
> good example here. Keep in mind that the length of a conductor, and its
> inductance, becomes some part of a wavelenth. At certain lengths and at
> certain frequencies thus approaching 1/4 or 3/4 wavelength, this
> combination will put a radio at the maximum voltage point above ground.
> Not a good thing. Remember that long grounds electrically will
> radiate.....into house wiring, TVs, VCRs telephones and a host of other
> things......namely the neighbors stuff.
>
> And finally......add more grounds.....not necessarly better. Ideally
> each piece of radio equipment should be connected to a central ground
> point. One station PSU is a good starting point. That ground point is
> then connected as in (c) above. This is referred to as a "star" ground
> system. Multiple ground paths will produce "ground loops" i.e. current
> flowing in the ground system. These are especially troublesome where RF
> is involved. Ground loops are oftem times the cause of audio humm and
> buzz in many applications. Different ground potential between the
> computer and the radio will cause humm or buzz problems in modes like
> PSK-31.
>
> I've found that crimp type connectors are very convenient. However,
> I've found better results when they are of proper size for the wire and
> are crimped with a proper crimping tool........and then soldered.
> Should one not use a proper crimping tool.......I then call 'em "mash
> on" connectors, most likely to fall off when least expected.
>
> If you have specific questions or concerns.......ask.
>
> 73
> Bob K4TAX
>
>
>
>
>
>
> Jack Malone wrote:
> >
> > I have RF floating all over my shack. Monitor it on a home built
Field
> > Strength Meter with 200 micro amp meter and a 2 inch ant on it. With
meter
> > located at op position I have full scale RF from my roof mounted dipole
with
> > 500 PEP out. I have NO RF in any of my equipment or cables. All
equipment
> > goes direct to a common ground bus which then goes to two 8 foot ground
rods
> > in XYL's flower bed (which gets watered daily) then to 300 feet of
Cattle
> > Fence, with all this tied to electrical power ground. From ground bus I
use
> > #00 stranded electrical wire to rods & fence with #6 to electrical power
> > ground. Also all my antenna coax cables have current chokes (10 turns
coax
> > of 10 inch in diameter) before entering the shack. All RF in my shack is
> > coming from my antenna radiation. With the 500 watts going into a dummy
load
> > I can find no RF on any equipment or in the shack.
> > --
> > Jack, W7EJJ
> >
> > ----- Original Message -----
> > From: "Carl Hyde" <cshyde@yahoo.com>
> > To: "Ten Tec" <tentec@contesting.com>
> > Sent: Friday, April 20, 2001 5:52 AM
> > Subject: Re: [TenTec] I'm getting reports of RF in my Pegasus ssb audio.
> >
> > >
> > > One of the best tools I have used to chase down RFI problems (besides
> > burning
> > > your lip on a microphone putting out a hundred watts) is the el-cheapo
> > Radio
> > > Shack SWR/field strength meter. In the field strength mode you can
sniff
> > around
> > > cables and radios for RF presence. There is no substitute for a good
RF
> > ground.
> > > I have one of the Ten Tec RF counterpoise kits that I used in a second
> > floor
> > > apartment a few years ago and it made a tremendous difference in
keeping
> > the
> > > RFI at bay. The arrangement of the Pegasus with the computer, monitor
and
> > radio
> > > is critical. You may have to try different locations and some snap-on
> > torroids
> > > on the connecting cables. Last night I looked back at the reflector
> > archives
> > > since the debut of the pegasus, I found that most of these problems
are
> > monitor
> > > and switching power supply noise being coupled into the Pegasus. Some
> > monitors
> > > seem to put out more noise than others and some owners have had to
replace
> > > noisy monitors. Other owners re-arranged their computer and monitors
in
> > > relation to the radio to cure the problem.
> > >
> > >
> > > =====
> > > Carl H.
> > > Remember, the opposite of PROGRESS is CONGRESS
> > >
> > > __________________________________________________
> > > Do You Yahoo!?
> > > Yahoo! Auctions - buy the things you want at great prices
> > > http://auctions.yahoo.com/
> > >
> > > --
> > > FAQ on WWW: http://www.contesting.com/FAQ/tentec
> > > Submissions: tentec@contesting.com
> > > Administrative requests: tentec-REQUEST@contesting.com
> > > Problems: owner-tentec@contesting.com
> > >
> > >
> >
> > --
> > FAQ on WWW: http://www.contesting.com/FAQ/tentec
> > Submissions: tentec@contesting.com
> > Administrative requests: tentec-REQUEST@contesting.com
> > Problems: owner-tentec@contesting.com
>
>
>
--
FAQ on WWW: http://www.contesting.com/FAQ/tentec
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Administrative requests: tentec-REQUEST@contesting.com
Problems: owner-tentec@contesting.com
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