[CQ-Contest] ANC-4 Noise Cancelling box

[k8bb at comcast.net]

It is also a good idea to ensure the remote "sense" antenna cannot get 
overloaded with RF from your transmitted signal. Whether your signal path 
uses the TX relay or if it is fed to an RX-only path, when you TX, the 
"sense" antenna is still active. If it is too near the TX antenna, the RF 
could cook the ANC-4. (I have heard of this happening from a few reputable 
ops ... )

I also use an ANC-4 in my shack (two, actually) but to ensure that does not 
happen, the RX paths go through a relay box that opens all RX lines when I 
transmit. This keeps any RF coupled from a TX antenna to an RX antenna from 
re-entering any equipment in the shack. Maybe not a big deal if you have 
reasonable separation between the antennas and/or are running low power, but 
I had a bad experience (running high power on a city lot) a few years ago 
that necessitated the precautions.

73!
Don Chisholm K8BB

----- Original Message ----- 
From: "N6KI Dennis Vernacchia" <n6ki_73 at sbcglobal.net>
To: "Cq-Contest" <cq-contest at contesting.com>
Cc: "W0MU Mike Fatchett" <w0mu at w0mu.com>
Sent: Saturday, March 24, 2007 8:16 PM
Subject: Re: [CQ-Contest] ANC-4 Noise Cancelling box


> Mike,
>
>    I was successful with nulling out a single noise source of a quarry
> in a canyon behind my house.
> To not have to deal with teh annoying T/R relay in the unit and since
> all my rigs have or have
> been modified to have a separate receive antenna port, my ANC-4 is always 
> in
> the receive path only. This way on CW I can run QSK too,
> which the ANC-4 can not even begin to deal with
>
> I am using an outside reference antenna  source close to the quarry's
> noise source.
>
> 73, Dennis N6KI
>
> W0MU Mike Fatchett wrote:
>> I have had an opportunity to play with one of these boxes and they work 
>> very
>> well  *IF* you can get a sense antenna that hears the same noise that you
>> have.  It should only be as long as needed to pick up the offending 
>> noise.
>>
>> In my case I have a very noise power line  to the NE only about 1000 ft 
>> from
>> my tower.  The power company has been notified so hopefully this will not 
>> be
>> a prolonged experience.
>>
>> I as able to erect a low dipole very close to the power line.  It is 
>> about 3
>> ft off the ground.  I started with a dipole that was 4 ft on each leg but
>> that did not have enough signal so I lengthened to about 14ft on both 
>> sides
>> and this worked much better.
>>
>> I found the extendable antenna to work a bit but it picked up all sorts 
>> of
>> birdies and other shack noise.  I also tried hooking up my R8 vertical as 
>> a
>> sense antenna but that was too much signal to handle.
>>
>> The unit comes shipped with a relay delay set to slow which I found very
>> annoying as I had to hear about 2 seconds of the power line noise before 
>> the
>> unit would engage after transmitting.  You can change this by moving a
>> jumper inside the unit.
>>
>> Mike W0MU
>>
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>>
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