I have local noise problems which come and go depending on time of day,
day of week etc. I didn't like the idea of having a noise cancelling
device in the high power transmit path, so picked up a DX Engineering
NCC-1 which is perfect for use with my K3, inserted between the antenna
OUT and antenna IN jacks. I have a horizontally polarized loop which I use
as the RX antenna on the K3 when I need to fight noise. A vertical doublet
antenna is used as the transmit antenna, which serves as the noise sense
antenna in receive when the NCC-1 is active.
To do this, the loop antenna goes to antenna port A on the NCC-1
(receive antenna input), K3 antenna OUT (from the transmit antenna)
goes to antenna port B on the NCC-1 (noise antenna input) and the
output of the NCC-1 goes to the K3 antenna IN. K3 KEY OUT goes to NCC-1
T/R CTRL to put it in bypass when the K3 is keyed.
Now I have 3 choices:
1. If I then select the RX antenna on the K3, the NCC-1 is inserted and I
use the quieter loop antenna for receive while nulling noise with the
NCC-1 controls. 2. If I don't select the RX antenna on the K3, the NCC-1
is bypassed, and the transmit antenna is used for receive. 3. If I select
the RX antenna on the K3, but turn the NCC-1 OFF, then I receive on the
loop antenna, but the signal passes straight through the NCC-1 from
antenna port A to the output without modification (sometimes that's all
that's needed, it's much quieter than the vertical when it comes to the
nearby noise pollution sources).
The NCC-1 can provide a very deep null on the receive loop antenna for
vertically polarized noise which is "heard" better on the vertical. The
trick is to correctly balance the levels of the two antenna inputs on the
NCC-1. The balance and phase controls are very precise and repeatable, and
the phase control has a wide range. Having the P3 to look at helps in
identifying the noise and finding what can be a very sharp (but deep)
null.
There are complications. One is that when the NCC-1 is active I need to
disable full QSK on the K3 in CW mode so that the internal bypass relay in
the NCC-1 doesn't make a lot of noise as it follows the keying.
The other involves antenna tuners. I use a KAT500, and if a frequency
change causes it to recall new L and C settings then the NCC-1 phase
setting may need to be touched up because the phase of the noise signal
from the transmit antenna is changed (and the NCC-1 null can be very sharp
indeed).
But for me the benefits have far outweighed the costs.
Bob NW8L
On Sun, 22 Mar 2015, Jeff Cathrow wrote:
Am contemplating a purchase of a DXE NCC-1 receiving antenna/noise phasing unit
very soon (tomorrow, actually---so I will have it in time for the WPX next
weekend) for use with my K3/P3/KPA500 and was wondering if anyone else in the
group uses one and how they have it configured. Apparently I will either need
to run it via my RX antenna jack or else with a sequencing unit (or RTR-1A
controller that DXE also sells) if I want to run it inline with my main
antennas.
My main usage will be for the reduction of RFI that I am often subject to here
in our condo complex (plasma or LCD TVs, wall warts and other electronic RF
garbage producers nearby). I currently use an old JPS ANC-4 with its attached
noise receiving whip that works fairly well---but could still be much better.
(I don't plan to buy the active antennas that DXE also sells with or without
the NCC-1; at least not for any foreseeable future).
I also use my Elecraft PR6 6M preamp affixed via the XVTR or RX antenna BNC
jacks and am wondering if I can run the NCC-1 through it with or without the
PR6 being on (I have it wired so that the PR6 activates only when I am on 6M,
IIRC)---but I am getting older these days and am more easily confused/dyslexic
when it comes to IN/OUT jacks than I used to. Will it be fairly easy to run
both together or will it require removing the PR6 if I want to run the NCC-1
through the RX ports?
Any user comments or thoughts on the subject will be appreciated; I have seen a
few YouTube videos on the NCC-1 and it looks like it can be very effective on
QRN coming from one particular source (like my ANC-4 but even noticeably
better). It certainly will be fun to see the noise disappear or fall
dramatically on my P3, too!
73, Jeff, NH7RO
K3/P3/KPA500
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