xphase qrm eliminator update

had my qrm eliminator about a month now. one comment comes to mind. choclate fireguard. cant seem to get it to work properly. tried lots of aux antennas from diepoles to mobile whip,peices of wire,at2lt. only result i get is like turning the rf gain down. seen lots of vids on you tube where it seems to work.dont know what im doing wrong.

Hi Richard,

Some people find the X-phase QRM eliminator to be brilliant, others not so.
They are great for reducing locally produced man made noise but next to useless for natural background noise, which is what I personally found. Much to be expected.
As you have found there are many videos showing how 'great' they are, but very few showing how to use one, (although if you dig around there is a couple). It might just be a case of persisting with it. Remember that it is designed to reduce noise, not actually eliminate it completely and it won't reduce 'hiss' like a DSP unit tries to.

One thing I have found over the years is having what is called a "radio ear", (bear with me on this one).
When I tune a radio, I'm listening out for intelligible signals and largely ignore the white noise hiss. I found my wife does pretty much the same. I suppose due to our age and a past history of listening to old AM MW radio and crackly vinyl records
My adult children on the other hand hear nothing but the 'hiss' and 'sshhh' sounds....
My grandchildren are much the same except my youngest grandson who thrills with excitement when a faint signal is present

Anyway, don't expect miracles with such devices. As mentioned, either persist with it or do as many others have done and give it up as a bad lot. Neither outcome is right or wrong, works for some and not for others.

73's
Victor

thanks victor. i'll keep on trying. i'll put it away for now. anyone else had sucsess with one of these things let me know..

There are some good videos on how to use the MFJ 1025/1026. Have a look at one or two of those and adapt them for yours. The controls are the same, main antenna gain, phase, aux antenna gain.

The main idea is to adjust the gain from both the main and aux antennas so they're both feeding the same signal strength into the circuit and then you adjust the phasing.

From the MFJ 1026 manual it says to do the following, (it may help to have someone in the area you can get to transmit whilst you're doing this.) Text in red is my explaining what you're trying to achieve to help you understand how it works.

With the power turned off:
The first four steps are is so we can see only the strength of the signals the main antenna is receiving so we can set the aux antenna gain
1) Turn the AUXILIARY ANTENNA GAIN control fully counter-clockwise.
2) Adjust the MAIN ANTENNA GAIN control fully clockwise.
3) Find a strong signal (why you ideally need someone with a normally strong signal near you you can get to transmit)
4) Turn the unit on, you should still hear the signal. Look at the receiver's S meter and remember the signal strength.
5) Adjust the MAIN ANTENNA GAIN control counter-clockwise, signal strength should decrease. Turn the control fully counter-clockwise.
This will knock the main antenna signal strength to next to nothing so we can now use the S meter on the radio to set the gain for the aux antenna so it's sending the same signal strength as the main antenna
6) Advance the AUXILIARY ANTENNA GAIN control clockwise. You should hear signals from the AUXILIARY antenna.
7. Adjust the AUXILIARY ANTENNA GAIN until the signal is just exactly the same on the S meter as the level observed on the MAIN antenna, or as high as possible.
Now we adjust the gain back up on the main antenna again so it's sending the same signal strength to the phasing circuit as the aux is
8. Advance the MAIN ANTENNA GAIN until you just see the S meter change.

(At this point we don't want the S meter to rise more than it did before you started to increase the main antenna gain so you have both the main and aux antenna sending the same strength signals into the phasing circuit)

9. Adjust the PHASE control for minimum signal. If the signal strength increases or won't null, change the position of the PHASE switch (you don't have this).
10. Go back and forth between the PHASE and the GAIN control that isn't totally against the stop while watching for a null. Adjust only one GAIN control, do not adjust the control that is fully advanced.

This step may take some practice until you get a "feel" for how the controls work..  


The notching is quite sharp, it's not that broad so may not cover more than a few channels without needing adjustment.

If you've got multiple sources of the same kind of QRM (eg Sky boxes, PLT modems, switch-mode PSUs) the box will only phase out the noise coming from one source. This is the problem I have in the very densely-developed part of the world I live in - everyone has noisy broadband! But it is well worth persevering with because if you've got one particularly noisy device nearby (as I have) there is still enough of a noise reduction to make it worthwhile.

26TC62 wrote:

If you've got multiple sources of the same kind of QRM (eg Sky boxes, PLT modems, switch-mode PSUs) the box will only phase out the noise coming from one source. This is the problem I have in the very densely-developed part of the world I live in - everyone has noisy broadband! But it is well worth persevering with because if you've got one particularly noisy device nearby (as I have) there is still enough of a noise reduction to make it worthwhile.

Yep bang on there!!!!!

i still need to know what aux antenna to use..does the noise floor need to be same as main antenna?

Hi Richard,

The best noise antenna I used with my X-phase was literally a piece of wire running around the shack floor, (tucked under the skirting). You want to make sure that the 'noise' antenna is picking up your local QRM and not your main signal. If you put a half decent antenna on the noise input you could very well start cancelling out the signals you want to receive(!!)

As mentioned above you won't be able to hone in on all noise sources, just concentrate on the interference causing the most problems, (hard I know when these could be multiple noise sources).
Mine was good for an offending noise coming through the house mains wiring which was always present even with the power to the house was switched off! The reason I no longer use my X-phase is that noise disappeared when a neighbour recently sold up and lo and behold, the noise disappeared

I still get interference that kicks in mostly around dawn and dusk, (PITA for greyline listening), which I can only attribute to a nearby properties solar panels plastered all over their roof, (invertors kick in when sun input is low on a lot of installations and should be downright illegal!) The X-phase just couldn't handle that spurious emission.

It's a hard fought battle nowadays Richard, but still worth persisting with if you're plagued with one main interference source.

Hope that helps,
Victor

Hi Richard,

I have a Wimo QRM Eliminator which I use for SWL/ SW DXing, fortunately 27/28MHz is clear of QRM here. The main antenna is a 81’ long wire & I use a six metre dipole as the ‘noise’ antenna. The Wimo works extremely well, but the controls do take a bit of getting used to and are quite sensitive. You will notice a drop in RF, but it won’t (shouldn’t!) make any difference to the sensitivity.
Best 73s,

John 26CT3352.