The AM Forum

Hello All
It seemed like a quiet night for ma nature and static on 160M, Wed JUL, 15. I have a lot of local buzz from the power lines. I was using my A3S 40M as the sense antenna or noise antenna to bring a sample of noise into my MFJ Noise Canceller. The A3S has quit entirely on me and there is no money to have someone go up the pole to fix/repair/replace.
What would be a good substitute antenna that I could build to bring that noise into my canceller so I can eliminate the buzzzz?
Thanks
Fred

Try a 6 meter mobile antenna.

Hi Fred,

Although I have never used the MFJ noise canceller box, friends of mine have.  The ones that seem to have the best results are those with a good noise pickup antenna.  End fed wires being unbalanced in nature generally pick up lots of noise.  Its important to have ample noise as detected by the MFJ box.  Keep in mind there can be multiple noise sources so the box will only cancel the one the noise antenna is detecting.  I would hook the end fed wire up to the receiver first and see if its the same noise your hearing and also that the noise is really strong.  Then connect it to the box and do the phase cancellation and you should be in good shape. 

73,
Joe-GMS 

OK Joe, GMS, Joe
And Jim
I tried that. The antenna mismatch of 6M freq and 50 ohms, will not let a radio that is looking for 50 ohms on 160M, to hear the buzz. The 6M radio heard that buzz but not the 160M radio.
And Joe, you're correct it must be the same noise as the transmit/receive antenna is hearing for the MFJ box to do its magic. Using the built-in whip as the AUX antenna will now hear noise and crap inside your house. That buzz thing was outside. I walked around with my Grundig 750 tuned to 1880 and the noise in the house was different from what it heard when I took the 750 outside.
The noise canceller really does work. The buzz or hash can be reduced down to about an S-4. Last night this thing was 10 over. And then the buzz was gone; the noise floor was S-8 and distant lightning was propagating into Western Pa.
I thought that, even with the sun still around at 8PM, that someone would have been listening.

I found a small amplified, tuneable, mag loop antenna stuffed away that hears the same noise I have in my 160M antenna system. I will use a keyed voltage to remove the 9Vdc from the preamp, when I transmit, and isolate that antenna from the MFJ box with an additional T/R relay. So, it will not introduce excessive RF into the MFJ box. The MFJ does have a fuse to protect that AUX input from too much RF.
I mentioned all of this, because I blew out that fuse one day and was wondering why the MFJ noise canceller was deaf on the AUX antenna inpoot.

fred

Vertical antennas tend to pick up lots of noise. I've used an old 102 inch whip antenna as my noise antenna.

Thanks for reminding me, Pete.
I have a vertical in the back that I think was used at one time for the AUX antenna. BUT that's where the the latest lightning strike took place and wiped out the coax leading to the house, and the MFJ remote antenna switch. I have to come up with a "Plan B" to get that 40M vertical signal back to the shack.
I looked and looked many many feet of the buried RG213 and the center conductor insulator looks like a voltage tried to work its way to the shield. I condemned the entire run.
I have a magnetic loop antenna 60 feet away and I could extend the vertical coax to the mag loop location and buy a used-but-good, ePay type of MFJ remote switch. 

Fred

I went out to try to connect my monitor radio to the vertical to listen for my buzz noise and it was approaching 8PM. This buzz slowly disappeared into the background and I was getting an S-5 noise. An hour later, 9PM, the static crashes were propagating in on 160M and the noise level was up to S-9.
I will start to monitor and test, or look for this noise, at 6 or 7PM and figure out what's going on.
This particular noise has bothered me during the winter months when there are QSO's on 160, "early" in the evening. It is not a street light buzz sound. Seems more electrical and even 40M has troubles with this buzz. There are some high tension lines about a mile from me.
I have a weather proof box for the amplified mag loop and will proceed to wire that in as my AUX antenna in the MFJ noise canceller.
The cost of a new Ameritron remote antenna switch and 150 feet of RG 213, to connect the dual band vertical to my mag loop coax, is not in my budget. The "high priority, must-get-it-done-before-winter" isn't gonna happen.
fred

Why would you need RG-213 for a receive-only antenna?

Hi Steve
RG 213 direct burial. It's 200 feet from the antennas and the shack.
If I was going to re-activate the vertical, it would require two 75 foot runs. There is a 39 foot long wire held away from the vertical element by 3 feet to be my 5/8 wave 17M antenna. The vertical is tuned for 40M and the wire gives me 17M. Those two coax runs would be buried and brought to another antenna that is a remote controlled magnetic loop antenna that is good for 80-20M, QRO power. At that location, I would have to buy another new Ameritron remote antenna switcher to include the vertical into the choice of antennas for transmit receive. The last remote switcher was destroyed by lightning.

Consider running inexpensive RG-6 to the receive antenna and skip the expensive remote switch.