[Elecraft] Timewave DSP-599zx

[Bob NW8L]

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 Fri, 2 Jan 2015, Jim Wiley wrote:

> We use a NCC1 here also, although with just a low 75 and 40 meter trap 
> dipole for the noise pickup antenna.  It is very successful in 
> eliminating noise from the neighbor's plasma TV, and other noise sources 
> that originate in our neighborhood from time to time.  It only works on 
> one noise at a time, of course, but  most of the time that is enough.
>
> - Jim, KL7CC
>