I bought this antenna on a 30 day trial, and just got it about 12 hours ago.
So far I'm not at all impressed. I live about 150 miles from an AM station,
at 810, in the SF/SJ Bay Area, which has a marginal signal, but usually
listenable. Putting a new PSU in a PC about a month ago increased the noise
in AM radios 70-100' from the PC to an almost unacceptable level. I had
hoped the antenna would boost the signal enough to knock down the noise.
There are times when I can get a good signal from the station, but certainly
less frequently than before.

The antenna consists of three parts: a 600-1800 KHz control dial, a ferrite
antenna and something called the antenna element. The latter is about 8"
long by 3" by 1.5" (high). The idea is that one puts the ferrite antenna
very near the radio and the antenna element in some other spot, then adjusts
the control dial to the max strength. I detect zero change in any AM
signal from the (C. Crane) radio anywhere on the dial. The antenna element
can be grounded. I modestly did this by hooking a wire (alligator clips)
from the element to the ground socket of an AC outlet (nail in the socket).
No change. BTW, when I was doing the experiment last evening, the signal was
pretty decent during that period. In fact, quite listenable. All this
without the device though.

I'll continue to experiment, but so far not so good. Comments?
--
Wayne T. Watson (Watson Adventures, Prop., Nevada City, CA)
(121.015 Deg. W, 39.262 Deg. N) GMT-8 hr std. time)
Obz Site: 39° 15' 7" N, 121° 2' 32" W, 2700 feet

Traveling in remote places in the winter. What's the best
tool to carry with you? An axe.
-- Survivorman, Discovery (SCI) Channel

Web Page: home.earthlink.net/~mtnviews

On Tue, 29 Nov 2005 11:36:09 GMT, "W. Watson"
wrote:

excerpted...

I'll continue to experiment, but so far not so good. Comments?

You've already got an 8" ferrite bar antenna in the C.Crane radio;
perhaps the twin-doozie deal just doesn't add that much.

bob
k5qwg

W. Watson wrote:
Putting a new PSU in a PC about a month ago
increased the noise in AM radios 70-100' from the PC to an almost
unacceptable level.

Why do you think that's a radio problem? :-)
--
73, Cecil http://www.qsl.net/w5dxp

W. Watson wrote:
I bought this antenna on a 30 day trial, and just got it about 12 hours
ago. So far I'm not at all impressed. I live about 150 miles from an AM
station, at 810, in the SF/SJ Bay Area, which has a marginal signal, but
usually listenable. Putting a new PSU in a PC about a month ago
increased the noise in AM radios 70-100' from the PC to an almost
unacceptable level. I had hoped the antenna would boost the signal
enough to knock down the noise. There are times when I can get a good
signal from the station, but certainly less frequently than before.

The antenna consists of three parts: a 600-1800 KHz control dial, a
ferrite antenna and something called the antenna element. The latter is
about 8" long by 3" by 1.5" (high). The idea is that one puts the
ferrite antenna very near the radio and the antenna element in some
other spot, then adjusts the control dial to the max strength. I detect
zero change in any AM signal from the (C. Crane) radio anywhere on the
dial. The antenna element can be grounded. I modestly did this by
hooking a wire (alligator clips) from the element to the ground socket
of an AC outlet (nail in the socket). No change. BTW, when I was doing
the experiment last evening, the signal was pretty decent during that
period. In fact, quite listenable. All this without the device though.

I'll continue to experiment, but so far not so good. Comments?

I'd change the power supply to a better brand.

Generally if you have atmospheric or man-made noise increasing the
antenna efficiency is just going to increase the noise along with the
signal.

You could try to make a directional antenna; this would increase your
desired signal more than your noise.

The antenna would have to be big, however. The wavelength at 800kHz is
somewhere around 370 meters and you'd need to use around 1/4 of this.

You could try to feed power supply noise to the radio antenna at just
the right amplitude and phase to null it out. This would be a good
subject for an undergraduate or even a Master's thesis in EE but
probably not a good thing to do in practice.

You could attempt to shield it. Rat Shack has some clamp-on ferrites,
you could put one of these on your power cord close to the end that
plugs into the power supply. You could also make sure that the PC case
is well shielded.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

On Tue, 29 Nov 2005 11:36:09 GMT, W. Watson wrote:
I bought this antenna on a 30 day trial, and just got it about 12 hours ago.
So far I'm not at all impressed. I live about 150 miles from an AM station,
at 810, in the SF/SJ Bay Area, which has a marginal signal, but usually
listenable. Putting a new PSU in a PC about a month ago increased the noise
in AM radios 70-100' from the PC to an almost unacceptable level. I had
hoped the antenna would boost the signal enough to knock down the noise.

The 'noise' is _also_ a signal -- just one that nobody wants to receive.
The "C. Crane's Twin Ferrite Antenna" happily 'improves' the reception
of the noise -- in addition to the signal(s) you desire.

Let me guess: That PSU was "Made in China".

Jonesy
--
Marvin L Jones | jonz | W3DHJ | linux
Pueblo, Colorado | @ | Jonesy | OS/2 __
38.24N 104.55W | config.com | DM78rf | SK

W. Watson wrote:

I bought this antenna on a 30 day trial, and just got it about 12 hours
ago. So far I'm not at all impressed. I live about 150 miles from an AM
station, at 810, in the SF/SJ Bay Area, which has a marginal signal, but
usually listenable. Putting a new PSU in a PC about a month ago
increased the noise in AM radios 70-100' from the PC to an almost
unacceptable level. I had hoped the antenna would boost the signal
enough to knock down the noise. There are times when I can get a good
signal from the station, but certainly less frequently than before.

Any rf noise put out by the computer ps is going to be picked up by
your antenna as well as the radio station you are trying to hear. So a
better antenna (if your new one is indeed better) wil just pick up
stronger power supply noise. It's moslty a null situation.

What you need to do is get that power supply fixed or replaced

- 73 de Mike KB3EIA -

"Tim Wescott" bravely wrote to "All" (29 Nov 05 09:16:58)
--- on the heady topic of " C. Crane's Twin Ferrite Antenna"

TW From: Tim Wescott
TW Xref: core-easynews rec.radio.amateur.antenna:220543

[,,,]
TW Generally if you have atmospheric or man-made noise increasing the
TW antenna efficiency is just going to increase the noise along with the
TW signal.

TW You could try to make a directional antenna; this would increase your
TW desired signal more than your noise.
[,,,]


I wonder if it would help putting up a short vertical and summing its
signal with such polarity that it cancels the noise from the main
directive antenna? This on the theory that most man-made noise is
by its nature vertically polarized.

A*s*i*m*o*v

.... If you're not making waves, you're not rowing the boat

W. Watson wrote:

I'll continue to experiment, but so far not so good. Comments?

As others have said, you should try to attenuate the noise at its
source. If it is radiated, you need a better PSU. If it is coming out
on the PCs AC line, line filters might help.

If the PC and KGO are not in the same direction, some sort of
directional antenna might help.

Of course, the ultimate solution would be to move to SF and get a really
big signal. But there are problems with that, too: I live abt 3-4 miles
west of KNX (50 KW, 1070 KHz) and my problem is avoiding it, not making
it stonger

Phil

"Tim Wescott" wrote in message
...
W. Watson wrote:
I bought this antenna on a 30 day trial, and just got it about 12 hours
ago. So far I'm not at all impressed. I live about 150 miles from an AM
station, at 810, in the SF/SJ Bay Area, which has a marginal signal, but
usually listenable. Putting a new PSU in a PC about a month ago increased
the noise in AM radios 70-100' from the PC to an almost unacceptable
level. I had hoped the antenna would boost the signal enough to knock
down the noise. There are times when I can get a good signal from the
station, but certainly less frequently than before.

The antenna consists of three parts: a 600-1800 KHz control dial, a
ferrite antenna and something called the antenna element. The latter is
about 8" long by 3" by 1.5" (high). The idea is that one puts the ferrite
antenna very near the radio and the antenna element in some other spot,
then adjusts the control dial to the max strength. I detect zero change
in any AM signal from the (C. Crane) radio anywhere on the dial. The
antenna element can be grounded. I modestly did this by hooking a wire
(alligator clips) from the element to the ground socket of an AC outlet
(nail in the socket). No change. BTW, when I was doing the experiment
last evening, the signal was pretty decent during that period. In fact,
quite listenable. All this without the device though.

I'll continue to experiment, but so far not so good. Comments?

I'd change the power supply to a better brand.

Generally if you have atmospheric or man-made noise increasing the antenna
efficiency is just going to increase the noise along with the signal.

You could try to make a directional antenna; this would increase your
desired signal more than your noise.

The antenna would have to be big, however. The wavelength at 800kHz is
somewhere around 370 meters and you'd need to use around 1/4 of this.

The ferrite antennas are already directional. That is one of their
advantages.

You could try to feed power supply noise to the radio antenna at just the
right amplitude and phase to null it out. This would be a good subject
for an undergraduate or even a Master's thesis in EE but probably not a
good thing to do in practice.

These devices are well known and sold at least by 2 ham manufacturers- MFJ
and Timewave(?).

Dale W4OP

Cecil Moore wrote:
W. Watson wrote:

Putting a new PSU in a PC about a month ago increased the noise in AM
radios 70-100' from the PC to an almost unacceptable level.


Why do you think that's a radio problem? :-)
When I turn the computer off, the radio station noise drops dramatically. It
doesn't matter if I use AC or DC. I can detect the large noise change in my
car from the garage.

--
Wayne T. Watson (Watson Adventures, Prop., Nevada City, CA)
(121.015 Deg. W, 39.262 Deg. N) GMT-8 hr std. time)
Obz Site: 39° 15' 7" N, 121° 2' 32" W, 2700 feet

Traveling in remote places in the winter. What's the best
tool to carry with you? An axe.
-- Survivorman, Discovery (SCI) Channel

Web Page: home.earthlink.net/~mtnviews