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Reviews Categories | Specialized Amateur Communication Products | MFJ-931 Artificial RF Ground Help

Reviews Summary for MFJ-931 Artificial RF Ground
MFJ-931 Artificial RF Ground Reviews: 22 Average rating: 3.9/5 MSRP: $89.95
Description: Resonates a random length wire counterpoise and produces a tuned artificial RF ground or places a far away RF ground at the station equipment by tuning out ground lead reactance.
Product is in production.
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G3UXB Rating: 4/5 Nov 6, 2017 18:24 Send this review to a friend
Does what it says  Time owned: 0 to 3 months
Just received mine hooked it up as instructed making sure my real ground was isolated from the station ground and performs as advertised I use it with the MFJ 901B tuner they work well together I can see on my Autek WM-1 meter how the reactance of the ground effects SWR. I did open up both units on arrival for the 'MFJ' QC check but both were good , I think MFJ QC is getting better but mine was tested in 2015 so I guess they don't sell a lot of these, I would have given it a 5 except for the cheesy capacitor they used!
M6WFL Rating: 5/5 Sep 21, 2017 14:28 Send this review to a friend
Great - Works as expected  Time owned: 3 to 6 months
My shack is on the third floor and suffered from earthing issues even with a thick copper braid connected to ground outside the house.
I added the MFJ-931 between the earth and my radio equipment, this gave an immediate reduction to stray RF on 40m. I also added a counterpoise which offers the same improvements on 20m. Therefore I am happy. My 931 unit is well made and works as it should. Great!
AC9KJ Rating: 2/5 Sep 5, 2016 16:25 Send this review to a friend
Worked for a few days, then quit  Time owned: 0 to 3 months
Worked fine for six days - then suddenly stopped working today. I had bought it through Gigaparts because I've had bad experiences with MFJ's service department in the past.
KK6ZTI Rating: 4/5 Mar 3, 2016 15:57 Send this review to a friend
Huge Improvement For 2nd Floor Station  Time owned: 0 to 3 months
I'm a new HAM whose only had this product for 1 day at the time of this posting, so I'll probably return with a followup review in a few months. Note this is for a latest model 931 with a 2013 build date. Apparently they aren't selling too well considering it's 2016.

I have a CHA-250B, live in a densely populated area and have a 2nd floor station.

My RX has been "ok" but my TX was horrible. Most stations I could hear wouldn't hear me, even many within favorable propagation conditions between us.

I setup the MFJ-931 with my FT-450D transceiver ground and a 70' counterpoise wire. I'm consistently getting subtle to moderate RX improvements and giant TX improvements on 80m & 40m since doing so. Basically it seems I can now talk to whomever I hear (given propagation), even to local stations which should be a little challenging on a CHA_250B. Will be seeing how this fares on 20m soon but anticipating similar results.

The catch is a 70' counterpoise wire looks pretty silly laid around my small station room. I'm hopeful shorter wires will work as well but am a little concerned about it, at least on 80m.

Build quality seems to be an issue with many. Fortunately I haven't noticed any circuit connection issues however my capacitance knob has no stop point, which if intentional is a big design flaw in my opinion.

My next endeavor will be installing an antenna counterpoise, which should take TX up another notch.

Why do I keep bolstering an expensive "dummy load" antenna? Beyond it's simple installation and (kind-of) low profile, I love reaching out thousands of miles, night after night.
MI0HPE Rating: 4/5 Jul 31, 2015 16:08 Send this review to a friend
Looks promising  Time owned: 0 to 3 months
I just acquired this recently, My shack is three floors up so no usable rf ground from the stake in the back yard. Results so far are very promising, needs more experimentation with counterpoises etc.
One of the nicest things about this is that the simplest solution can also be the best one.
WI7B Rating: 5/5 Mar 28, 2015 10:33 Send this review to a friend
The Other Half of Your Antenna  Time owned: 0 to 3 months

I have a #26 stealth long wire antenna strung from my 2nd floor condo. Without the MFJ-931 resonating my balcony counterpoise, I would not be able to transmit efficiently. Your counterpoise is the other half of your long wire antenna. The RF current flowing through it is a match to the RF current following through your antenna. More is better here. The MFJ-931 allows that to happen. In addition, there are no complaints of RFI from neighbors. They don't even know I'm transmitting 300W and all this for $100. If I could give this 6-7 stars, I would. Best improvement for my station, ever!
VA2PBJ Rating: 5/5 Jul 9, 2014 21:33 Send this review to a friend
Great Product  Time owned: 0 to 3 months
It's one of this things that is indisposable when you need at and no big deal when you don't.

I bought it, but my longwire and 20m vertical were taken down for tree removal. Time to put them back up to really get this thing working.

It arrived and I did the usual inside inspection. All was good as every MFJ product I owned has been.

I hooked mine up to a 2 foot pipe (electrical conduit) I pounded in the ground. The earth is rocky here and it has not proven to be a great ground. It is what it is.

The only working antenna I have is a 40m ocf. No deflection on the current meter for 40 and above, but from a balanced antenna it was no surprise. Not so on 80m. For the first time I was able to tune it down to 2:1. I guess when you go out of band, it kicks in.

Time to put up the other antennas and get on the air.

It's something I've thought about for a while and I am glad I took the plunge. If I was not in a metal sided house, I might have considered throwing a wire across the floor and tuning that.

It does have two shortcomings though. The current meter should be more sensitive and I can't figure out an omission of a light for the meter.
KJ4NWZ Rating: 5/5 Jun 26, 2014 19:13 Send this review to a friend
Better review  Time owned: more than 12 months
In my last review of the MFJ-931 i gave the unit a 4/5 rating. I'd like to upgrade it to a 5/5. I've had the unit for more than a year, I now know EXACTLY how to use it and my rain gutter antenna is most happy with it. They have the perfect marriage.
VE3TKB Rating: 5/5 Dec 27, 2013 15:15 Send this review to a friend
Works just fine  Time owned: 0 to 3 months
I live on the second floor of a four story apartment building. I use a balcony mounted MFJ-1622. I am a long way from a decent ground so today when my MFJ-931 arrived I hooked it up to my TS-520S and ran a 15 foot wire to my baseboard water heated radiator. The difference was significant. My RFI is all gone and I get a little quieter receive signal. I only run 10 watts here as I am mainly on JT65-HF and I must say it works fine on all bands I use from 10-40 meters. If your shack is far away from a good RF ground I would highly recommend trying this. The construction of the unit is sturdy and I popped the lid and noticed no flaws or cold solder joints. A good addition for the Cliff Dwelling crowd :)
KL7T Rating: 4/5 Jan 24, 2013 10:32 Send this review to a friend
no problems  Time owned: 0 to 3 months
Received this product yesterday. I use an indoor loop antenna in my bedroom, no ground connection during the winter. I took the cover off and found everything to be perfect. I hooked it up in counterpoise mode with two wires on the floor. I could adjust the inductance and capacitance to maximize ground current. I am giving it a good rating because it worked exactly as expected.

Has it increased my signal output? I don't think so.
In the summer I do run a 35 foot ground wire out the door to a copper rod driven into the ground. (my bed room happens to have a door to the
outside). This artificial ground is supposed to reduce the impact of the length of the ground wire in this situation. Also in the summer I use the MFJ-1788 mag loop antenna.
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