FWIW I've used the MFJ-1026 in line with a IC-746 using the MFJ-1026's
internal RF relay without problems. I did not use the RF sensing
feature but hooked up a separate keying line. I used this mostly on 75
and 40 meters. I use a 50 ft long wire for a sense antenna with my 75
meter dipole. The unit can work wonders but expect to spend a lot of
time fiddling with the setup.
Since you are adjusting amplitudes and phase angles from two separate
antennas, anything that changes the arrival time or phasing from either
antenna effects the null. Touch up the tuner to minimize SWR and you may
be tweaking the noise null again. Change frequency too much and the
null also changes so you are tweaking again.
If you have more than one source of noise the best that you may do is
null the worst source. If your sense antenna does not hear the noise
then you will not get a null. (If your sense antenna is quieter than
your transmit antenna you can use the 1026 as a TR relay and just listen
to the sense antenna and forget trying to null the noise.)
Just now I tried it on S5 line noise on 75 meters. It's quiet enough
today that I wouldn't normally bother with a noise canceller; however,
I could not get a null. The noise actually sounds a little different on
the dipole as opposed to the longwire so the sense antenna (longwire) is
not hearing the noise the dipole is hearing.
As a test of the unit, I tuned in a local highway info station on 1620
kHz. Starting with both aux and main antenna gain at minimum, I set
each gain to just light up the S9+20db segment on the 746. From that
equal RF amplitude start and with a little tweaking I could get a null
of this station to S7. That should give an idea of what you might expect
given a point noise source and a well located sense antenna.
I didn't have a quality control issues.
Pat
wa4tuk
On 12/30/2012 3:12 PM, George wrote:
For a diagram of how to hook up an ANC4 or MFJ1025/1026, see:
http://va3cr.net/accessories/ANC-4.htm
Should work with any rig having a separate RX jack and eliminates the need
for TR switching in the noise canceller box.
The external noise antenna is critical for effectiveness - the MFJ whip
antenna is not enough. Also, as noted, it's only good for one source. Like
peeling off the layers of an onion, some crying may result.
Noise is just one of the joys of centre of the city DXing...
73, George VE3YV / K8HI
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