"Richard Harrison" wrote in message
...
Crazy George wrote:
"---do a bibliographic search of Engineering Index, or Scientific
Abstracts, or whatever that school has access to."

Excellent advice from George. Motorola`s Extender usually included a
switch on the radio control head to enable or defeat Extender operation.
The only reason I can think of to defeat Extender operation is to
demonstrate its effectiveness, which can be compelling.

Richard:

One of the problems with the first production Extenders was no limit on the
total duration blanking. Since the individual pulse length was fixed, it
was possible to get 100% blanking on a readable signal, with the right noise
pulse length and rate. Motorola figured this out about the same time we
did, and quietly modified the circuitry to limit total blanking percentage.
On the other hand, the salesmen with one noisy spark plug in their demo
vehicles loved the switch. But, that's been 40+ years ago, and the details
are hazy.

--
Crazy George
Remove NO and SPAM from return address
snip

Best regards, Richard Harrison, KB5WZI

Tarmo Tammaru wrote:

Randy,

Speaking of the horse's mouth! I am concerned that Jason might have too high
an expectation of what the noise canceler can do. See if the below is right.

1. It can cancel out the noise from a single stationary noise source that is
received via groundwave, and will in general do nothing for atmospheric
noise as you would have on 75m.

Correct!


2. For an automated adjustment method to work, and keep it within his means
and time frame, he will have to tune to a frequency where there is no signal
present. He should then be able to retune to a differenr frequency within a
few KHz, and still have the nulling.

Correct!


3. Consistent with 2, the receiver's AGC voltage is as good an indication of
noise amplitude as any. In fact, it can't be measured AFTER the AGC, as for
instance the audio output.

Correct!


Tam/WB2TT
***********************************************
"Randall R. Gawtry" wrote in message
...

One of the other people noted that it was important to do a lot of

reading,

research and analysis of your own - I'll second that!

If you haven't run across it yet, start with the term "Null Steering".

'nuff said for now,

Randy Gawtry
Timewave Technology Inc.

Randy,

Thanks for your response. The obvious thing you would like to do is to have
the software be smart enough to distinguish between signal and noise. But
then the hardware becomes moot, and you have invented a better DSP noise
reduction circuit.

BTW, I am considering getting an ANC4 to get rid of power line noise on 6
meters. Fortunately, the noise is coming from the North, a very seldom used
beam heading.

Tam/WB2TT

Dave,

Thanks for the info. In my case, the source seems to be a bank of 4
transformers on a pole about 300 feet away. Weirdest thing I had was S9
white noise from about 40 to 55 MHz with about 50% amplitude modulation at
around 50 KHz. Turned out to be a 60 amp cartridge fuse in my fuse box about
to go bad. I think the 50 KHz was a mechanical resonance in the fuse.

I don't know about the 746, but my 756 has dual watch capability, which lets
you listen to two frequencies at the same time. It would be interesting if
they would let you vary the phase of the secondary channel..

Tam/WB2TT
"Dave Shrader" wrote in message
et...
My ANC-4 is sitting on top of the ICOM 746. I have a short piece of
coax, 7 to 8 feet, to a doublet with a total length of 8 feet on the
floor against an outside wall.

Works Great!

I've used the ANC-4 for almost two years. While in Massachusetts the QTH
was 100 meters from the New England Power Grid with three sets of high
tension [ 67,000 volts] three phase power lines [nine wires total].
The power lines were generally quite quiet but during summer humidity
and/or thunderstorms they would get 'noisy'. The ANC-4 reduced the noise
to S1 typical levels.

Here in New Hampshire, my local noise source is the local LAN where the
router is four feet from my receiver. Similar results with the ANC-4.

BTW, it was given to me as a gift by W1KSZ who picked it up on e-bay for
about $60.00. Thanks many times over, Dick.

DD, W1MCE

Tarmo Tammaru wrote:

Dave,

Thanks for the info. In my case, the source seems to be a bank of 4
transformers on a pole about 300 feet away. Weirdest thing I had was S9
white noise from about 40 to 55 MHz with about 50% amplitude modulation at
around 50 KHz. Turned out to be a 60 amp cartridge fuse in my fuse box about
to go bad. I think the 50 KHz was a mechanical resonance in the fuse.

...

There are lots of weird noise sources. As a kid in the 40s, I was part
of a family visit to an old farm west of Bethlehem Pa., in what was
definitely "fringe area" TV reception. The man of the house was telling
my father about the strong zig-zag pattern that sometimes showed up on
the screen, blanking out the video and often lousing up vertical synch.
He wanted to know if the FCC would track down the interference; he
thought it was a ham about half a mile away. Just then, the interference
started, and right after, his son came downstairs to join us. A little
while later, his daughter went upstairs, and the interference cleared
when she got to the top. Without saying anything, I went over to the
stairway switch and turned it on and off a few times. "On" caused the
interference. When we swapped the bulb with one in a floor lamp, the
floor lamp caused the same interference. It has been one of my enduring
regrets that I didn't ask to keep the bulb. It was probably thrown out.

Jerry
--
Engineering is the art of making what you want from things you can get.
¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯ ¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯ ¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯

Tam- never had much luck with one got (also 6 meter op), but , also, BEWARE
if into weak signal stuff - has 6 dB LOSS on recieve (DC bands, who cared,
background noise worse than that, but at VHF ???) If you want one, make
you good deal! Jim NN7K



Tam wrote:
Randy,

Thanks for your response. The obvious thing you would like to do is to
have
the software be smart enough to distinguish between signal and noise. But
then the hardware becomes moot, and you have invented a better DSP noise
reduction circuit.

BTW, I am considering getting an ANC4 to get rid of power line noise on 6
meters. Fortunately, the noise is coming from the North, a very seldom
used
beam heading.

Tam/WB2TT

On Fri, 08 Aug 2003 13:31:25 -0400, Jerry Avins wrote:

Tarmo Tammaru wrote:

Dave,

Thanks for the info. In my case, the source seems to be a bank of 4
transformers on a pole about 300 feet away. Weirdest thing I had was S9
white noise from about 40 to 55 MHz with about 50% amplitude modulation at
around 50 KHz. Turned out to be a 60 amp cartridge fuse in my fuse box about
to go bad. I think the 50 KHz was a mechanical resonance in the fuse.

...

There are lots of weird noise sources. As a kid in the 40s, I was part
of a family visit to an old farm west of Bethlehem Pa., in what was
definitely "fringe area" TV reception. The man of the house was telling
my father about the strong zig-zag pattern that sometimes showed up on
the screen, blanking out the video and often lousing up vertical synch.
He wanted to know if the FCC would track down the interference; he
thought it was a ham about half a mile away. Just then, the interference
started, and right after, his son came downstairs to join us. A little
while later, his daughter went upstairs, and the interference cleared
when she got to the top. Without saying anything, I went over to the
stairway switch and turned it on and off a few times. "On" caused the
interference. When we swapped the bulb with one in a floor lamp, the
floor lamp caused the same interference. It has been one of my enduring
regrets that I didn't ask to keep the bulb. It was probably thrown out.

Jerry

I think that one may have been intended for an embassy somewhere...


Eric Jacobsen
Minister of Algorithms, Intel Corp.
My opinions may not be Intel's opinions.
http://www.ericjacobsen.org

Without saying anything, I went over to the
stairway switch and turned it on and off a few times. "On" caused the
interference. When we swapped the bulb with one in a floor lamp, the
floor lamp caused the same interference. It has been one of my enduring
regrets that I didn't ask to keep the bulb. It was probably thrown out.
================
That bulb was probably an old coiled 'Edison' type . They were /are known to
form a tuned circuit resonating in the old TV band 1 ( about 48 - 62 MHz)
acting as a TX when power is applied.

Frank GM0CSZ / KN6WH

Eric Jacobsen wrote:

On Fri, 08 Aug 2003 13:31:25 -0400, Jerry Avins wrote:

... It has been one of my enduring regrets
that I didn't ask to keep the bulb. It was probably thrown out.

Jerry

I think that one may have been intended for an embassy somewhere...

About a year later, I read about such a bulb in QST. The author believed
that Edison-effect electrons excited a self broad-band resonance in the
doubly coiled filament, sustaining oscillation by a mechanism I forget,
but that seemed reasonable at the time. Incandescent lamps are filled
with low-pressure nitrogen to avoid damage from the Edison effect, and
interaction with the gas figured in his explanation. It was that
explanation that led me to build an open-air triode. I was surprised as
anyone when that worked, and I took it as a confirming instance for the
now-forgotten explanation.

Jerry
--
Engineering is the art of making what you want from things you can get.
¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯ ¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯ ¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯

Frank Dinger wrote:

Without saying anything, I went over to the
stairway switch and turned it on and off a few times. "On" caused the
interference. When we swapped the bulb with one in a floor lamp, the
floor lamp caused the same interference. It has been one of my enduring
regrets that I didn't ask to keep the bulb. It was probably thrown out.
================
That bulb was probably an old coiled 'Edison' type . They were /are known to
form a tuned circuit resonating in the old TV band 1 ( about 48 - 62 MHz)
acting as a TX when power is applied.

Frank GM0CSZ / KN6WH

Thank you thankyouthankyou! I've been called a crazy liar more than once
over that bulb. There was no channel 1 when that incident happened, but
I suppose that a small change of geometry could raise the frequency. The
explanation in QST had it that the frequency was swept over a fairly
large range as the voltage varied during a cycle.

Jerry
--
Engineering is the art of making what you want from things you can get.
¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯ ¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯ ¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯