Why would reception improve - and noise drop - when the chassis
ground to the receiver is removed? This is noticeable on SW, but *very*
noticeable on MW.
Ground connection is to faceplate screw of a (verified) grounded 3-prong
outlet, the best grouond I can muster, at the moment. Should I try a
simple length of "counterpoise" wire as a ground?


Tony


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"Tony Meloche" wrote in message
...
Why would reception improve - and noise drop - when the chassis
ground to the receiver is removed? This is noticeable on SW, but *very*
noticeable on MW.
Ground connection is to faceplate screw of a (verified) grounded 3-prong
outlet, the best grouond I can muster, at the moment.

Most likely picking up common mode noise from your household wiring. Those
grounds are great for 60 Hz, not so great for 1 MHz. Grounds often don't
make a lot of difference for SW reception, but in some cases can make a
world of differene (short run directly to an earth ground).

Please, DO ground your devices. Here in Finland, the BBC on shortwave
19 metres comes in at S=9 without grounding and S=9+40dB with grounding.
Also weaker stations on so called tropical bands are not audible without
this "counter part" to the antenna.

Matti Ponkamo, 33 years of experience, Naantali, Finland


"Brenda Ann" kirjoitti viestissä
...

"Tony Meloche" wrote in message
...
Why would reception improve - and noise drop - when the chassis
ground to the receiver is removed? This is noticeable on SW, but *very*
noticeable on MW.
Ground connection is to faceplate screw of a (verified) grounded 3-prong
outlet, the best grouond I can muster, at the moment.

Most likely picking up common mode noise from your household wiring. Those
grounds are great for 60 Hz, not so great for 1 MHz. Grounds often don't
make a lot of difference for SW reception, but in some cases can make a
world of differene (short run directly to an earth ground).

In article ,
Tony Meloche wrote:
Why would reception improve - and noise drop - when the chassis
ground to the receiver is removed? This is noticeable on SW, but *very*
noticeable on MW. Ground connection is to faceplate screw of a
(verified) grounded 3-prong outlet, the best grouond I can muster, at
the moment.

Two possible explanations come to mind:
1. Local radiating noise sources are mostly "e" field, as you are very
close to them ("in the near field"). So connecting a ground may improve
your reception of the noise more than it does the signal.
2. You may have noise on your wiring's Green Wire. EVERY PC I've ever
opened has used the Green Wire as its operating ground, as the electrical
code forces it (the metal enclosure, being a conductive object the user
can touch, MUST be so grounded). So you may have digital hash on your
ground, being conducted into your receiver with you antenna acting as a
counterpoise.

Should I try a simple length of "counterpoise" wire as a ground?

Sure. Also, see if you can't rig up some sort of 'extension' to your
original antenna, so you can have a 'balanced' antenna that doesn't need
to work against ground. I say that knowing a chorous of voices will
immediately arise, saying "That will work better with an
impedance-matching balun." True, but just connecting with a piece of
twinlead or even zip cord will still work.

--

R F Wieland Newark, DE 19711-5323 USA 39.68N 75.74W
Icom R75 Heathkit GR-81 Inverted-L in the attic
Reply to wieland at me dot udel dot edu

Tony Meloche wrote:

Why would reception improve - and noise drop - when the chassis
ground to the receiver is removed? This is noticeable on SW, but *very*
noticeable on MW.

AC power in the US is at an extremely low frequency of 60
Hz, which has a wavelength of around 5000 kilometers! This
means it takes a 5000 km long length of wire before you see
just one full cycle. 360 degrees in 5000000 meters, or about
0.000072 degrees of phase shift per meter! The voltage at
all points along a 10 meter length of wire at 60 Hz is for
all intents and purposes, exactly the same at both ends, and
it's an excellent ground.

Not so at 10 Mhz (10,000,000 Hz), where the wavelength is
just 30 meters. You'll see a whole RF wave across only 30
meters of wire. 360 degrees in 30 meters is 12 degrees per
meter of phase shift. That means the voltage and current at
each end of the wire will be significantly different, and
it's NOT an excellent ground. In fact, it's more like a 1/3
wavelength antenna that's grounded on one end, than an RF
ground. **** poor ground, it is.

You didn't mention whether you live on the ground floor. If
not, you're already doomed for having a good quality
electrical ground at *RF* frequencies.

Also, your results are poor with the ground, probably
because AC power system noise is coming in through your
ground wire. At RF frequencies, an AC power ground may be
very poor, because a length of wire becomes an antenna, even
if one end is grounded. Once you have 20 or 30 feet of wire
before it goes to an actual earth ground, I think all bets
are off.

The best ground for an antenna system is probably the
shortest and most direct to earth, independent of and as far
away from noisy wiring as possible. In this case, it would
be better to ground the antenna and feed your signal in via
coax cable, than attempt to ground the receiver chassis.
(Unless it's an old tube radio with a screw terminal for the
ground. These may provide a measure of electrical safety.
But otherwise... avoid.)

Ground connection is to faceplate screw of a (verified) grounded 3-prong
outlet, the best grouond I can muster, at the moment. Should I try a
simple length of "counterpoise" wire as a ground?

Given how noisy AC wiring can be, it can't hurt to
experiment. Try running the counterpoise wire so it's as
low to the ground (or floor) as possible. It may well
outperform your AC "ground", which probably is feeding in
massive amounts of electrical noise directly into your
radio. If it turns out to work better one way over another,
don't argue with results. :-)

This, of course, is all my opinion. Please accept it as
such.

-- Ross





Tony

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Ross:


I really appreciate your response to this (now aging) post, and the
final result was that I ran a ground wire a total of 30" long to a
galvanized steel rod sunk 6' in the the ground right outside my ground
floor window. Problem solved. It is most noticeable on MW, where it is
*much* quieter. Again, appreciate your response.

Tony


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TM,

Household Electrical Ground and a 'good' RF Grounding Point often are
two different things. IOW: "Good" Electrical Wire Code and "Good"
Radio RF Reception are not necessarily the same thing.

YDTRT: What you did is the right thing to do.
- - - Try It and If It Works: Use It / If Not Don't Use It.

?Q? What Radio? Type of Radio? Were You Using ?
- Direct A/C Powered ?
- - A/C Adapter to DC Power ?
- - - Battery Power ?


GROUNDING a Process of Alternatives:

1. If you can install a Ground Rod and a short(est) Ground Wire to
connect to you radio then: Try This First.
- - - IMHO: A Ground Rod and Grounding Point at the Antenna with Coax
Cable as a FeedLine to the Radio would be Better.

2. Try a Cold Water Pipe if you have metal piping in your
house/building.

3. If the above does not work for you: Then try using a counterpoise
vice an actual ground.

4. Household Electrical Ground at the A/C OutLet is usually the Last
Option in Today's High "Man Made Noise" (RFI/EMF) Household
Environments.


TIP: If this is a Stand-A-Lone Battery Powered 'portable' SW Radio
that is simply using the built-in WHIP Antenna:
- You may wish to try a "Place Mat" ground plane reflector.
- - Plastic Place Mat (12"X18") or Paper Desk Blotter (24"x36") with
some Aluminum Foil under it connected to a 'good' ground (or not).
- - - With some 'portable' SW Radios in some locations this is the
Magic That Works. (No Theory Required - Hey, Simply It Works! -
SomeTimes )


iane ~ RHF
..
..
= = = Tony Meloche
= = = wrote in message ...
Why would reception improve - and noise drop - when the chassis
ground to the receiver is removed? This is noticeable on SW, but *very*
noticeable on MW.
Ground connection is to faceplate screw of a (verified) grounded 3-prong
outlet, the best grouond I can muster, at the moment. Should I try a
simple length of "counterpoise" wire as a ground?


Tony

Ross I agree 100 percent with your suggestion to experiment. I installed a
12-gauge wire directly from my receiver down to a 6-foot ground rod. Total
length of ground wire about 8 feet. At the low end of the receiver, around
100kHz, the ground is a definite improvement. At the high end near 30MHz it
actually introduces more noise. My solution was to put a switch in the
ground wire near the receiver. When I do a major frequency change I simply
flip the switch back and forth for the best position and, as you said, not
argue with the results. When I'm not using the receiver I leave the ground
hooked up, it makes for a nice static discharge path.

Al KA5JGV



"Ross Archer" wrote in message
...
Given how noisy AC wiring can be, it can't hurt to
experiment. Try running the counterpoise wire so it's as
low to the ground (or floor) as possible. It may well
outperform your AC "ground", which probably is feeding in
massive amounts of electrical noise directly into your
radio. If it turns out to work better one way over another,
don't argue with results. :-)
-- Ross