JPS ANC-4 noise canceller (additional comments)

Mike Meehan mmeehan at
Wed Dec 6 10:06:40 EST 1995

Jay (and others interested in killing noise),

Bottom line report on the ANC-4: Without it I couldn't operate!

I've got a strange (new) noise problem with no set pattern and
when it's there, my station goes down. Possible causes are
electric fences, and during the heat wave last summer, 
we lost our pole pig. They put a new one up having higher 
line voltage and better regulation, but there may have been
a price to pay. There wasn't any noise at first, 
it all started months after the transformer installation, so
I'm just not sure...

I've got an old Signal One which uses RX gating on signals 
within the 8Mhz PB. The first filter is a 6-pole 25kc wide job 
and so if there is a slow signal (like another cw station) 
within this passband, not only the noise gates the RX, but 
also the cw station! The ANC4 works by adding 2 out-of-phase
signals together: the desired signal w/noise and the signal 
from the noise antenna (mostly noise). Thus there is no undesired
gating of the RX...I'm not real hip on the new rigs they have
today (at least I can work on my CX7A), but if they dont
already have rigs with this type of noise blanker in them,
I expect you will see them soon! Meantime, Doug and George
at JPS should be recognized as producing one of the finest,
highest quality station additions to come out in a long time! 
(My rig is 25 years old---you get the idea. A wise old ham 
once told me to put your money in your antennas!)

You do have to fiddle with the 2 knobs (and 2 push-buttons)
on the unit. And the most important part is getting the 
noise antenna right. At my station, I found the best noise 
antenna to be a hunk of RG8 laying on the ground between my 
shack and tower (about 100'). Not much problem with IMD with
this as my noise antenna. On many stations I could still 
"hear them in there" without noise cancelation, but the 
fatigue reduction alone makes this unit valuable for me. 
There are also numerous stations that simply couldn't be 
copied, but came in just fine with the ANC4 enguaged.

Other observations include having to retweak the phase knob
when orienting the beam in a new direction--as you would
expect. I can easily tell when the ANC4's noise amp is 
overloaded---you get more noise than you started with :-D

(A comment on power: Old timers recall the Signal One is 
capable of 250 watts output, so there is no problem with 
the ANC4 bypass realy (even at 2:1 vswr--my loaded 40M 
dipole has crummy BW). Also, for qsk, you need to replace 
a resistor (supplied) so the "hang time" on the relay is 
reduced. The effect of using the longer time constant is 
that you get a fraction of a second where the ANC4 is 
bypassed---this is nice in a way cuz you can verify how 
well the box is working...)

You get the hang of it pretty fast...(In reading Jay's
experience, I somehow got the feeling that he does more work
than I do to get it to play. I think he was "wringing out"
the capability of the new unit and probably doesn't switch
to the dummy load etc. etc., now that he has his noise ant
situated. Comments Jay? I guess well have to wait for your
noise to come back. Want some of mine? :-D )

On this note, I would like to solicit comment from those that
have tried to DF noise. I'm interseted in the antenna and
setup used to snoop out the culprit(s).

Oh, one other thing Jay forgot to mention was that JPS has a
"try b4 you buy" policy on this thing. They realize it might
not solve your particular problem...(I think its 10 days and
you need to check with the distributor you use (if you dont
go factory direct) and confirm that they will honor it...

Happy noise busting!

Kindest Regards,
- Mike Meehan (AK6N)

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