>From the comments received, the success of the ANC4 is *highly* dependent
on noise source(s), noise type, and the availability of a sufficiently
strong noise signal on the sense antenna.
Novel uses include nulling out a local loud station and avoiding the use
of the rig's internal noise blanker.
A particularly good-to-know caveat was that the unit can overload with BC
energy.
My decision - I'm going to have Santa bring me one and use it in
conjunction with some other techniques (shielded loop, low dipole, etc.)
for the Stu Perry. I'll report anything useful learned. I don't expect
it to be The Answer.
Comments follow and thanks to all the responsders.
73, Ward N0AX
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I have not found mine to provide a worthwhile improvement in real
operating, but I have seen it work in testing. I think the trick is
to get the noise antenna picking up the noise but not the signal with
an amplitude within the range of the gain adjustment, which is small.
An external amp and/or attenuator may be needed.
---
I am blessed with a pretty quiet QTH, as well as having visited the same, but
on a few occassions, my ANC-4 took a very un-welcomed s 5-9 noise out of
the picture. A few times at the farm and a couple of times at VP5. They do
a nice job on cleaning out a noise before the receiver sees them. They can
be a little touchy on the nulling out of the noise/interference, but usually
not. It really works on one signal/noise, but can cover a whole band for some
of the wide band noise problems. I think it works great for DXing, but too
much of a hassle for most contesting, except maybe single band types. I'm very
glad I have mine. It helps here at the apartment from time to time, at the
farm on a few occassions and I take it with on trips, for sure! Very few
noises that I have encountered couldn't be helped, but there were a few.
---
IF you have done everything else, then yes. I found mine useful for
'stuff' that nothing else would touch.
Would I try EWEs/short beverages/BIG beverages/loops first, YES ...
those would be less $, THEN go the ANC route ...
---
For those problems (i.e., minor power line noise & BC harmonics) not worth the
money or effort!
----
It was moderately helpful on the few spotty noise problems that occurred
during the period. Most of my noise is broad-based, ambient-level (local
Amtrak line, and adjacent HV power line) with their constant buzz all up and
down the line -- no specific point source. This didn't help with those at
all, as expected..
I found some overload problems, apparently from local BC station, and
perhaps because I was using too large a "sense" antenna (my 40m Delta Loop
up 90 feet). Anyway, I set the jumper to activate the low-pass filter
(supposed to cut off BC band) and also the BC notch filter which I adjusted
to null out the 1150 khz station a mile and a half away. It only knocked it
down about 10 db, didn't really solve the overall overload problem of the ANC.
I think for the specific-point noise sources it does help, from what I've
heard from others and for the limited experience I had with it. But my
DSP59+ made more of dent in my overall noise problems than the ANC4.
----
The ANC-4 is excellant on and was designed for power line noise.
---
I just got mine up and running about a month ago. The jury is still
out but overall its proven its usefullness. I use it to phase two EWEs and it
"seems" to help. I have used it on 6 meters to reduce line noise to the West
and it works as advertised.
---
Yes, they are. See attached file, plus I have one -- the day I unpacked
it and put it on the shelf, my power line noise disappeared. And stayed
gone. Then, a couple weeks ago, I loaned the ANC-4 to a friend who had
noise problems. Result . . . MY noise is back; HIS is GONE. Go figure, huh?
---
I don't have the ANC-4 but a hombrew version I constructed
from a QST article several years ago. Essentially what the unit does
is take a signal from a "sense antenna", vary it's amplitude and
phase, and combine it with the signal from the main antenna. In essence,
it makes a 2 element directional array. My experience is that the box
is very effective on ground wave signals because they have stable phase
and amplitude characteristics. I can null local BC stations into the
noise and copy other stations on the same channel. It is also very
effective on power line noise if there is only one source.
Unfortunately, not the situation at my last QTH! I also had good results
on 160m during nightime (after sunset variations died down). I was able
to get 20db of attenuation on some of the big multi-multi's during
contests which allowed me to hear a lot of DX that I otherwise could
not. The null on these skywave signals varies considerably. Sometimes
deep stable nulls other times I had to fiddle with the controls a lot to
get even a minimal null. The only downside is that occassionally you
can put a null in the direction of the desired station. Careful sighting
of the sense antenna (It must be able to hear the undesired noise) and
a little practice made mine a very useful accessory.
---
I bought one about a year ago and have used it from time to time but I
dont use it "constantly". From my personal experience here are the some
"tricks" in making the item useful
1) You should have a couple of different noise antennas. The trick is to
get as much manmade noise and not atmospheric noise into the "noise
antenna" as possible. If you use too good an antenna you can actually
end up introducing extra atmospheric noise into your receiver while
trying to tune out the man made crap. In general small antennas close to
the noise source work better.
2) The ANC4 can only cancel out 1 noise source at a time. If you have
two noises (or more)...This is because it basically feeds the noise
signal back into the frontend at an equal amplitude and EXACTLY 180
degrees put of phase, thus cancelling. In my case I can choose to take
out the monitor birdie at 1822.5 or the power line noise but not both at
the same time.
3) If your noise antenna is too good you can actually introduce BCI
products..again smaller noise antennas are better.
4)It can be very tricky to tune especially on abnd that has a lot of
atmospherics as well as manmade noise. The noise null when right is
quite sharp and requires jockying the noise gain and phase controls
quite a bit.
Is it worth $150 not really it has less than $30 worth of parts in it
and they wont give you a schematic so you can trouble shoot it yourself
which tells you how simple it would be to "knock off" if you had the
schematic. Does it tune out the noise....in some cases....but its no
panacea....
Because of their policy of not providing a schematic so you can repair
it yourself I would recommend that you not buy it ..but for that reason
alone. I have not tested this policy recently so you may want to ask
before you buy, maybe thats changed.
---
I've used an ANC-4 for the last year or so, almost exclusively on TB. It is
effective for severe power-line noise. I can't say abt BC harmonics, as I have
none here. I first borrowed an ANC-4 from ******, as he could never get his
to work at his QTH. He had tried using both the small collapsible whip antenna
provided with the unit, as well as a short vertical made from hookup wire.
Neither worked for him.I use a shielded loop, tuned to 1.9 MHz for the
noise-sense antenna. It is built from an old ARRL handbook article on miniature
rx loops. It's 5 ft on a side, in a square configuaration. I have it mounted
inside my garage, above the shack. My main tx antenna for 160 is a FW loop, in
the vertical plane, abt 100 ft at the top and 40 ft up for the bottom leg. It's
closest oint to the sense-ant is abt 40 ft. With this setup, I find the ANC-4
will reduce an S-9 or slightly more local power-line noise to approximately S-
0. That's slightly misleading tho, since the attenuation of the ANC-4 is abt 6
dB or one S-unit by itself, even with no noise present. I find it's greatest
advantage to be when the band is both vy noisy (from power line type noise) as
well as very crowded (from other loud DXers chasing the guy I need). The ANC-4
will allow you to forgo the use of the dreaded noise-blanker in the rig, which
as you know, will produce terrible problems with ANY close-by, strong signals.
The best combination, as far as overall noise reduction is the use of BOTH the
ANC-4 and the rig's noise blanker, but as noted above, I can seldom stand to
use the NB in pileup situations. Based on my good experience with the borrowed
ANC-4, I returned it to ******, and purchased my own. ******* has continued
problems trying to get enough noise form his noise-sense antenna in order to
cancel the noise from the main tx ant. He and I have had many talks at ham
conventions with Tom Jacks, of JPS, the maker of the ANC-4. abt ******'s
problem with the unit. Mr. Jacks' opinion is that ******* is just not getting
enough of a noise signal yet. So bear this in mind: you may have to experiment
with several (many perhaps) diffferent combinations of sense antennas before
finding one that is entirely effective for you use. I have found the ANC-4 to
be absolutely no use in reducing or eliminating the general band "hiss" or
thunderstorm crahses. And although they claim it can fllow QSK, it does not.
But the rare times when I get extreme, local power-line "snot", the ANC-4 has
really made the difference in making the Q and missing it.
---
I couldn't see paying for one of these, especially
since you can only cancel one noise source at a time.
I've been playing with homebrew versions, which are both
cheaper and more versatile, especially when used with remote
active antennas and loops. No one method is the total
answer, I guess.....
---
I got one, but haven't played with it very much at all. I have some
pretty hefty line noise, but the noise antenna wasn't adequate for
it. I need to play with the noise antenna some.
However, I had some computer noise at a couple of spots on 10m that I
tried the box on, and it went from s-7 to absolutely zero after a
little fiddling with the controls.
I think the box has potential.
---
My ANC-4 does not null out most noise. I suspect that the unaffected noise
is either from multiple sources such as that big power line to the south or
the noise is being propagated in. I say this because there is some noise
that the ANC-4 eliminates, and it works on TV birdies. Still, the best use
I find for it is to null out ***** who is 6 miles away and really loud. If
you have a point noise source or a local who overloads your Noise Blanker,
the ANC-4 will null it if as long as both the main and noise antennas can
hear it.
---
Kinda late on this but wanted to say mine is worth the $100 I spent on
it. It really SAVED my butt the first night of CWSS. I had a terrible
noise on 80m....s9. Showed up 4hrs before the start of the contest. I
ended up stringing an 80m dipole as the noise receiving antenna but it
nulled it to nothing and 80m turned into my "money" band this year.
**** used it during CQWW SSB and it saved him from electric fence
noise.
So, it works for me and has helped. I bought mine used for $100 bucks.
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I have had one for about a year and i relly works on local interference. I
gets rid of computer birdies and TV birdies., CD hash and local power line
stuff. The secret in a variety of noise pick up antennas. I built a 5 position
switch and have serveral different polarity and lenghts of noise antennas
(inside on outside the house).
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