Unboxing the QRM Eliminator

[@Centar1964]

You do not want the signal to be the same strength in both a and b that will cancel the wanted signal. The sense antenna should be something small that picks up the noise but NOT the wanted signal. A good starting place is set the main antenna to full and the phase and ant2 at 50% and then play with the phase and ant2 for least noise. The placement and size of the second antenna is very important to get the noise but not the signal.

[@n4hnhradio]

I would like to say that you are correct, but you aren’t. You need the noise level at least close to equal with both antennas. Then use the phase knob to cancel the noise. If you have two antennas with opposing gain lobes and nulls, you can use the device to electrically rotate your receive pattern, effectively canceling signals from a direction you don’t wish to hear. It actually just attenuates the signals. But a weak signal might be eliminated. I’ve used that technique for years.

[@Centar1964]

I meant the wanted signal not the noise...and that is a cool way to use with 2 antennas with opposing gain lobes. I have one on order now... as I live next tp a power sub station. @@n4hnhradio

[@elkabong6429]

Interesting demo, thanks! I have the MFJ-1026 and I find it works fairly well for most noise in my area.

[@n4hnhradio]

My MFJ-1026 does a great job, until I run my amplifier. It’s just susceptible to the RF coming back through the RX antenna. Thankfully I haven’t needed it since the power company repaired the poles. 73, de N4HNH

[@PlanetObservatory]

I have one of these and it is a miracle worker. I use an old k40 cb antenna thrown on a metal awning as the 2nd antenna

[@n4hnhradio]

That’s a great way to repurpose something.

[@PlanetObservatory]

@@n4hnhradio it is taking my noise from s9 to s1 or 2

[@n4hnhradio]

When not using the device to cancel noise, if you have two of the same type horizontally polarized antennas, installed perpendicular to one another, the phase knob can be used to electrically rotate your receive pattern - similar to rotating a beam antenna.

[@PlanetObservatory]

@@n4hnhradio I would not have thought of that. Great idea. my antenna is basically laying underneath powerlines, the aux antenna anyway. It is picking up no good signal so it works real well for cancelling, but nothing else the way I have it setup. Main antennas I have a 40m dipole and a vertical in the form of a military sectional antenna about 40 ft up. I can switch back and forth between the dipole and vertical

[@Littlelewie151]

Just got mine this week and it rattled. Ferrite transformer floating around inside.

[@n4hnhradio]

Oh no!

[@MONTY-YTNOM]

To be fair you don't have that much background noise :) You should try in the UK. It's mental :)

[@n4hnhradio]

For now it isn’t bad. But I have had 15dB over S9 of power line noise, until the power company fixed it, which took over a year. There was loose hardware and two blown up lightning arrestors. The next time the power line noise rears its ugly head, I will shoot a video. 73, de N4HNH

[@MrRadiorobot]

Here in the UK in an urban setting Vdsl is normally the main culprit but there are many others to contend with on the hf bands.. S7 - S9 of noise 160-10 meters is the new normal at my qth.

[@n4hnhradio]

Oh no! I am concerned that there are so many electronic devices around us to cause RFI these days. Wireless phone chargers, wall-wart power supplies, cheap LED lights, plasma TVs, burglar alarms, door openers, traffic lights, green house lights, solar chargers, and more. 73, de N4HNH

[@MrRadiorobot]

@@n4hnhradio I think future operations for me are portable/field activities..get away from most of the noise, limit myself to vhf/uhf from home. To this end I have ordered myself an ft-891 to take out in the car or on foot..I am getting a go pack together. Its no great loss to me actually, hf has always been problematic for me from home, at one time it was me causing rfi to the neighbours, tv radio etc, now tables have turned and in part its them causing it to me with no recourse or cure!! A great many hams here in the UK will struggle to comply with the icnirp requirements recently introduced, most of the population here is living very close together ..its a rediculous situation, uhf rfi everywhere and everyone walking around with a cell phone ghz transmitter slapped to the side of their head, and then as hams we have to get out the tape measure and calculator to ensure compliance in the hf portion of the radio spectrum that to my knowledge is relatively harmless sub 100 Watts..I understand similar government requirements are heading the way of US hams? The best of luck with that!

[@aj2isotadxing]

Glad you finally got it! Same with mine, knobs not aligned. For the money , it’s tough to beat. The DSP in these radios is so good, once you use this, it’s the icing on the cake. I put some electrical tape over the led on mine because it was kind of glaring lol. Good luck with it.

[@n4hnhradio]

Thanks my friend. I hope it outlasts my MFJ-1026. The real test will be when I fire up the amplifier. I assume this thing can handle up to 100W through it. I’m almost certain it cannot handle the 200W the radio is capable of. But most of the time I run 20 to 25W when driving the amplifier. With the MFJ, it’s the RF of 700W or more off the antenna that takes it out. 73, de N4HNH

[@Tocsin-Bang]

I've just ordered a kit version, so I can do my own QC. I have a chassis ready with the sockets mounted.

[@n4hnhradio]

That’s great, Stephen. When you build it yourself, you know how to repair it later, if needed. 73, Doug

[@StuartM0TTQAmateurRadio]

I have had very similar experiences to you - I bought this exact model from Amazon because I couldn't be bothered to repair my MFJ1026 again (popped a transistor) and I also had the same issue with the incorrect control knob installation! I have persistent switch-mode QRM and looking at the waterfall on the SDR I uses as a panadapter for my 590SG it is very quick to adjust. For what these units cost, I think they are good value for money.

[@n4hnhradio]

Indeed, I’m hoping this outlasts the MFJ-1026. I haven’t found any information about the power limit for this device. Since there was no operating manual, I can only guess that it can handle 100W, like the MFJ-1026. My radio can put out up to 200W. I’m betting this device cannot handle 200W. But I usually run 20-25W, driving my amplifier. You guys across the big pond must have more power line noise than we have. You aren’t the first to mention the horrendous noise you have in the UK. My power lines are above ground, even near the same height above ground as a couple of my dipoles. I figured yours were below ground and that would be better. When my power lines are noisy they are terrible. But it’s usually a loose bolt, a dirty insulator, or a blown up lightning arrestor. Our local power company will fix it. It took 14 months the first time but in the last couple of years, they get out here within 2 weeks after I report a problem. 73, de N4HNH

[@Nobody-ld7mk]

Purchased one of these devices and I'm pleased in general with the Construction Quality, to my surprise the pots are smooth as silk. Just about no way to properly label one of these boxes due to the countless configurations of the three controls in achieving the desired lead lag phasing to generate a necessary null in cancelling un-wanted noise. Controls should be labeled (1) "Amplitude & Phase" (2) also in degrees due to the fact both signal amplitude and phase shift in degrees are affected by the turning of any of the three potentiometers. Piddled around with mine on a scope and these devices clearly preform as advertised.

[@danielwinfrey1]

Hey Doug, another great video as usual. I just received a QRM Eliminator that is identical to yours, but with a Green LED for Power and a Red LED that lights during TX. I have not tried TX yet, but it seems that with a very simple 29 feet of stealth antenna wire on my 2nd story shack floor, there are some strong benefits. I have noise in the upper half of 40 and 20 meters in the later part of the day, its a neighbor thing as far as I can tell and its erratic and inconsistent. Question for you (or anyone) , on the FTDX10 , what cable do I need to go from the QRM Eliminator RCA to the FTDX10 ? Is it RCA to the 10 pin Linear jack? That makes sense to me, but there is also a 13 pin ACC jack, not certain how to proceed, but definitely NOT going to key up until I figure that out. Some confusing info as alway on the web, so asking my N4HNH Brethren first- Thanks, Dan KN6NDW

[@n4hnhradio]

Hi Daniel! The link below is the cable I ordered as a backup to key my amplifier. I haven’t used it yet because I’m using the band data cable from Elecraft. But the cable at the link below plugs into the Linear port and sends the PTT signal to the RCA plug. It should work with your QRM Eliminator. I use a Heil FS-2 foot switch with my QRM Eliminator. It transmits the radio and provides a PTT for an amplifier or, in my case, the QRM Eliminator. I’m using a Heil PR-781 mic with a boom arm, so the FS-2 is convenient. I key with my foot and my hands are free to type into the log. The RCA cable from the FS-2 takes care of the QRM Eliminator without me needing to connect to my radio. www.ebay.com/itm/254970401621?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=7qaf0C6WSW-&sssrc=2349624&ssuid=_vRUbW8STJ6&var=&widget_ver=artemis&media=COPY 73, de N4HNH

[@danielwinfrey1]

@@n4hnhradio I’m really glad to hear that as I have that exact one one on order Doug, but I was having some doubts. I have told you this before, and I am honest about this, starting in this hobby this late in life, and not having an Elmer, your instruction on series of the FTDX10 has been invaluable to me. When I studied and tested through the different class segments, I understand and have no problem, but putting it all in practice in my shack I do get overwhelmed and your series has been awesome! Have a great Thanksgiving, stay healthy, I’ll be listening for you in the air sir. Thanks again, Your friend, Dan KN6NDW

[@n4hnhradio]

Thank you so much, Dan! It means so much when someone like you confirms that my time is well spent. I will be your Elmer as much as possible. I understand getting from the theoretical to the practical. I’ve been there. We all go through that phase. Before you know it, you will be looking back and thinking, “how did I get this far so quickly?” I recommend watching the FTdx10 series in order. The videos tend to build upon one another. Also, don’t forget that videos from the other playlists teach techniques that can be applied to amateur radio as a whole. Such playlists as “Noise Interference on HF”, “Working DX”, “Learning Ham Radio”, and even videos for other radios. 73, Doug

[@marks2254]

I’m m noticing that a lot of radios have more than one antenna input so that you can switch between antennas without having to unconnected and connect antennas. It would be nice if in addition to just allowing switching, manufacturers would also include a QRM circuit that allows one to choose which antenna will be used for listening then let you use the other one as the QRM antenna. Would that be pretty easy thing for them to do?

[@n4hnhradio]

I’ve suggested the phase type noise eliminator function be added to a dual receiver transceiver. The Yaesu FTdx5000MP and FTdx101D or MP have multiple antenna connectors, and you can assign which receiver uses which antenna. They also have the option to connect a dedicated receive antenna and automatically switch to it during receive, while using a different antenna for transmit. 73, de N4HNH

[@rogershults5607]

Hello DOUG N4HNH I got a Yaesu FTDX 101 MP QRM Eliminator is turned off can you transmit 200 watts ON it another problem I would have with The qrm Eliminator all my HF antennas come in the House to a big 2K a Ten Tec 229B manual Antenna tuner on the back of my Big Ten Tec 229B antenna tuner I got a coax jumper running to antenna switch box for two different Radios Yaesu FTDX 101 MP ICOM IC 7610 thank you I subscribed to your KZbin channel you got some great videos 73

[@n4hnhradio]

Hi Roger. You cannot run 200W through the QRM Eliminator. I use an external amplifier and I rarely run more than 25W into the amp. When I go to 60 meters that is the exception, but I can’t run over 100W there anyway. But the QRM Eliminator is only a temporary solution, until your power company sends a crew out and fixes the root of the problem. 73, de N4HNH

[@lomgshorts3]

Seems to be just an audio passband filter. The sensing antenna looks to be nonfunctional.

[@n4hnhradio]

No, that’s not how it functions.

[@marks2254]

Hi Doug - If both antennas are hearing the same things (signal and noise) why doesn’t the signal get cancelled out at the same time as the noise is being cancelled? I think maybe I missed the point. Thank you. Mark W6EUJ

[@n4hnhradio]

Both antennas are receiving the same noise, but not necessarily the same signals at the same strength. I use my best antenna for the band as the main antenna. I adjust the gain knobs until the noise floor is about equal on both antennas. I then adjust the phase knob. Then the signal, which is stronger on the main antenna, is left. The S-meter reading for the signal will be lower than normal, because of the gain settings and the phase cancellation, but I can now hear their voice better. 73, de N4HNH

[@n4hnhradio]

I should also mention that you can use the phase cancellation to turn two perpendicular horizontal dipoles into an electrically steerable array. Each dipole will have a figure 8 radiation pattern for the band it is cut for. Install them perpendicular to one another. Use the phase knob to tune in or null out stations you do or don’t wish to hear. It’s a nice use for the eliminator when you aren’t needing it for noise cancellation. Once I got my power company to remedy the noise from their poles, I used the eliminator to create a steerable array. Note of course that it is only steerable for receiving. 73, de N4HNH

[@marks2254]

Thank you Doug

[@madmax2069]

Did you use the power cord that was included with the eliminator, if you did is the white wire the center connector ?

[@n4hnhradio]

I didn’t use it. I already had a power cord that fits, was connected to my power supply, and wasn’t currently in use. I do recommend that you use the supplied power cable, unless you already have one with a RF choke installed. The power cable that came with my eliminator included an RF choke. In answer to your question, the white wire is connected to the center of the connector and it should be connected to the positive post of your power supply. 73, de N4HNH

[@madmax2069]

@@n4hnhradio awesome, thanks for the answer. That's what I figured, I just wasn't sure and didn't want to end up cooking the unit on a guess. Being that I'm not at home I had no way to test, I was going to try a AA battery, some wire and a light to make a simple test circuit, but didn't have a light to test with.

[@madmax2069]

@@n4hnhradio when I initially bought the eliminator I bought a cheap wall wart PSU for it. The eliminator did power up with it, but that wall wart produced some pretty severe interference which made it useless. while the eliminator was able to null the interference from the wall wart on whatever radio the eliminator was hooked to, everything else was screaming in pain, the interference of that wall wart was far far far worse than the interference I initially bought the eliminator for. So I ended up buying a $45 linear power supply for it, and everything is much quieter. Hooked up and now it doesn't make the radios sound as if they want to kill me. 73 and thanks again.

[@n4hnhradio]

It’s hard to beat a good ole linear power supply. I use an Astron RS-35. As far as switchers go, the PowerWerx I have seems okay. I use it to power my 2m base station. But I prefer linear. 73. de N4HNH

[@madmax2069]

@@n4hnhradio I do own a Astron SS-30m and it seems pretty quiet, pretty much limited for space and a 30amp linear PSU would have been far too big and heavy so I had to choose a switcher. but I lucked out with it. For the QRM eliminator I bought a Pyramid PS8KX and it's quite hefty for only being a 6Amp PSU, but it's a tradeoff going with a linear PSU, hefty but quiet vs smaller but noisy. I didn't know that Pyle took over Pyramid (or was it vice versa, they're both pretty much Sound Around now). bought a Pyramid and the box and documentation all say Pyramid, but the PSU itself is stamped Pyle, now hopefully it's not a Pyle of crap. But I knew I would have to get something like a linear PSU for the eliminator for the best possible chance, but I just didn't listen to myself. I was probably hopping to luck out and it would have been quiet, but nope it's anything but.

[@hueypilot1950]

Is the QRM eliminator looking for a switch/ relay to short the center to the ground on transmit?

[@n4hnhradio]

Yes. You must provide it a PTT connection via RCA jack. 73, de N4HNH

[@EUC_Senior]

Just curious on what type of noise you are trying to get rid of? QRM is man made noise like L.E.D’s and other things that are man made. QRN is atmospheric noise. If you are trying to get rid of QRN then I doubt that this device is what you need. N2DMI

[@n4hnhradio]

This device cancels pulse type noise, such as that from power poles or automobile engines. In my case it’s noise caused by the arcing between power lines and hardware on the power pole. It is considered QRM, because electric power is man-made.

[@EUC_Senior]

@@n4hnhradio yes I have been a Ham for 41 yrs, I know all of this. 73’s N2DMI

[@n4hnhradio]

You asked what type of noise. I answered your question. The device is called a QRM Eliminator. It is not a QRN Eliminator. There are subsequent videos that show it in action.

[@EUC_Senior]

@@n4hnhradio That is what I asked you. 73’s

[@PT9KK]

Another great video. To escape from the Chinese market, I bought my kit at the following address a43.veron.nl/projecten/x-phase-qrm-killer/ That's the Dutch Amateur Radio Society. They also sell a broadband antenna. Some of my ham radio friends use a vertical or directional 2m antenna to pick up noise on HF so not to decrease the signal one wants to listen. I haven't tried that method yet, but will do it in the future.

[@n4hnhradio]

I prefer not to buy Chinese as well. But I wasn’t aware of an alternative. If you connect two perpendicular dipoles cut for the same band, you can use the phase control to electrically rotate the pattern of the antennas. I’ve done that with my MFJ-1026, before it died the last time. 73, de N4HNH