Chet,
Your experience using noise sense antenna brings up something I am
curious about; whether pointing noise antenna at same heading as signal
antenna will have affect on cancelling ability.
At present my 6m-eme yagis are pointed az=060 and noise sense antenna is
fixed at az=130 (3-elem side mounted to a tower leg).
If I find correlation with antenna headings, I might mount the noise
antenna on the same mast as the eme array but 8-foot above them. With
isolation relay in line the noise Rx will be offline in Tx.
Also characteristics of the noise waveform may affect how well phase
nulling works. I also see noise floor occasionally rise on 2m which is
something switched on and then off (appliance of some sort). My house
is clean except for the microwave oven.
Still experimental; more results to follow.
73, Ed - KL7UW
On 4/16/2022 4:26 PM, chetsubacco...@snet.net wrote:
Thanks for the info Ed, quite appreciated.
And, similar to what Lyn has stated, I have had mixed results using a
Timewave ANC-4 on 6M. When the noise source was S7 from one direction about
2 miles away, I was able to use a low 3 el vert noise yagi to reduce it to
S1-2. But when the noise was radiating from the powerlines right in front of
my house with a broad azimuth, I could not do too well.
73,
Chet, N8RA
-----Original Message-----
From: elecraft-boun...@mailman.qth.net <elecraft-boun...@mailman.qth.net> On
Behalf Of Lyn Norstad
Sent: Saturday, April 16, 2022 5:12 PM
To: 'Ed Cole' <kl...@acsalaska.net>; magic...@groups.io
Cc: elecraft@mailman.qth.net
Subject: Re: [Elecraft] Using MFJ-1026 Noise Canceller on 6m-eme
Interesting setup, Ed.
I've used the MFJ-1026 in the past, but found that satisfactory (i.e.:
meaningful) results were hard to come by when used in the recommended
manner.
Please keep us posted on your tests.
73
Lyn, WØLEN
-----Original Message-----
From: elecraft-boun...@mailman.qth.net
[mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Ed Cole
Sent: Friday, April 15, 2022 8:32 PM
To: magic...@groups.io
Cc: elecraft@mailman.qth.net
Subject: [Elecraft] Using MFJ-1026 Noise Canceller on 6m-eme
Diagram of final configuration: http://www.kl7uw.com/6M_NOISE_CANCEL.jpg
This a basic phasing unit to reduce band noise on HF bands. But first I
tried it on 6m where no null was achieved.
Next I configured to use the 1st IF output of my dual-Rx Elecraft K3 running
in Diversity mode which phase-locks both Rx to the main VFO.
That involved using an outboard SDR to detect the 8.215 MHz IF signal and
supply audio to my computer. Sensitivity was too low on the second Rx so
required opening/inspecting cables inside the radio. I found the synth coax
not seated well to the second Rx. Re-seating the connector fixed that.
But I still had too low an audio level from the 8-MHz SDR to drive wsjt-x.
A bit of research found the proper dialog box to adjust mic gain.
Apparently the K3 line output is much higher than the SDR audio (LP-Pan2).
Original design involved using an external preamp for the 6m noise antenna
(3-element yagi) but I found I had adequate gain using the MFJ internal
preamp set to gain=2 (out of 10).
To add additional RF protection to the MFJ, I added a coax relay to
disconnect the aux input of the MFJ. It does have a TR control line to give
protection to the main Rx line, but none to the aux Rx input. My main Rx is
fed by a preamp at the tower located behind a TR relay.
I adjusted audio levels for main and aux inputs so wsjt-x read 36 on the
audio bar meter for each. With both inputs it read 40.
Placing the K3 into diversity mode I could null about 6-dB (reading dropped
to 32/34.
No idea if this is enough noise reduction for 6m where I regularly see
S5 pointing NE toward MR, Pointing SE local noise often drops to S2/S3.
One s-unit is 6-dB.
Next is to test with actual eme signals.
73, Ed - KL7UW
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