QRM problem

Hi All.
Just got set up after 25+ years and i am suffering some bad qrm which sounds electrical in nature. Its definately air born and giving me a solid S7.
So after trying everything i have ordered a mfj-1026. Has anyone any experience with one of these? Guess i'm asking if they work.

Cheers all

Have you done the basic tests?
Put the radio on a battery and killed the power to the house?
Switch each circuit off in turn to see if the qrm dips down.
If it does, then look at each device on that circuit. (computer psus, "wall wart" chargers are some of the worse offenders)

Thanks for replying.
Yes done all of the above and even took all the batteries out of the wireless house alarm no difference at all.
Its a very strong constant signal with no let up.
I'm hoping the 1026 can do something with it.

Fair enough Jason,
Good luck with it mate

Can you confirm a few things please.

You have turned off all power to your house and run of a battery and noise is the same or not lower ?

What antenna and coax are you using and how is it mounted ? Ie scaffold pole or 1 ft above the gutter on a bracket ?

Also you can use ferite filters / chokes to help but if airborne or direct pick up from wiring when plugged into the mains from your or close by source, neighbours devices , ADSL lines , wifi and lots more .

Start with that please , and let me know the results .

Ok.
So i have switched mains off and run on battery, noise still the same and in strength.
I have a thunderpole 5 mounted directly to my house wall at the peak so it is about 16ft above my roof line. Running 20ft of rg213 and my swr is 1.2 on all channels.
I have noticed that even when on battery if i unplug the coax and touch a screwdriver to the center pin on rig the interference is present at about an s5 so im now thinking its localized possibly a neighbour.

That is extremely strong and nearby . A neighbour most likely and unfortunately not much can really be done about that , can try a choke but doubt bring down that much if that strong .

Im hoping the mfj-1026 will be able to null it as it is just one signal, fingers crossed i guess.
Could you recommend a choke as i was thinking of fitting one anyway?

Jason what does the noise of the interference sound like , because for about month here in London (North) we have been getting a noise that sounds like the only way I can describe is like someone keying a mike and something shorting out crackle sound bit vague I know sorry lol ,its only on higher frequencies ie: 27:555 (on all modes) upwards and stops just before 28mhz plus it's all over UKFM not the on the mids and you can hear it 26mhz going downwards,  I'll  try and do a video of it .
Just went out to the shack and the noise is not as bad ATM so didn't do a vid ,if it comes back as bad as it was I'll try and video it.

Hi Nubster.
Its sounds very much like a transformer buzzing noise its also on all the bands but on about the same frequencies you have mentioned. Its very prominent on AM.
I dont have any power lines or transformers near me so i'm a bit stumped, unless a neighbour has some serious electrical problems.

I am getting similar up here in Seaham . constant s5-s7 everyday of qrm . i have a venom 1/2 wave on a 21' pole ( about 9'0 above the guttering) running 12mtrs of rg213

Well i'll post a report of this mfj-1026 when i get it up and running, hopefully a good one. Might even do a little youtube video if it works.

JasonRees wrote:

Could you recommend a choke as i was thinking of fitting one anyway?

Make your own if you've spare or excess coax. Make a coil of 5 turns of RG213 or RG58 with a 4.25" internal diameter. 110mm PVC waste pipe from MKM etc is idea to use as a former.

Does that really work as well as a ferrite choke for interference?

JasonRees wrote:

Does that really work as well as a ferrite choke for interference?

Yes it will. The main difference is that the air wound ones are very narrow banded so not really good for multi-band antennas but OK for single band use like CB. Air wound ones though are reactive. If you get it wrong it can make things worse so you do need to get the construction right in regards to diameter and number of turns so the inductor (which is what we're creating when we make a coil from coax) is tuned for the frequency we want to choke.

What I gave you was from a chart made by Steve G3TXQ who actually constructed them and measured the choking so it's actually verified and not the <insert random length coiled up any old how> air wound choke you'll find suggested elsewhere.

A bit of reading and the chart: http://karinya.net/g3txq/chokes/

Many thanks for the info I might just give this a go.
I think I have the correct pipe kicking around in the garage somewhere, thanks again.

Cheers mark.

If you have a portable radio (medium wave transistor radio?), go walkabout.
The MW portable has the ferrite rod aerial which is directional.
IIRC the aerial nuls when you point it at the interference source (and away)
The maximum pickup is 90 degrees to the noise.
Reading what Martin Nubster is saying, it sounds like PLT (Using the mains wiring to distribute internet around the house) .
The amateur bands are "notched out" as amateur radio is a protected service. 11 metres is not, so in that respect you're stuffed

BigTone wrote:

Reading what Martin Nubster is saying, it sounds like PLT  (Using the mains wiring to distribute internet around the house) .
The amateur bands are "notched out" as amateur radio is a protected service. 11 metres is not, so in that respect you're stuffed

I had this, it turned out to be a street over, the house causing it was 230ft from my antenna with a row of houses between me and them, and at the time it affected the amateur bands so I was able to get OFCOM to sort it.

Tony, I had message on our WhatsApp radio group and one of the guys on there has the same noise as I get and his up North so this noise maybe country wide ,also he was using his Kenwood that's obviously been wide banded he was listening on 27:555 usb

Well this is a big disappointment as it makes using it from home impossible.
I've ordered another aerial as you need two for the mfj-1026 to work.
Might have to get my amateur licence at this rate.

JasonRees wrote:

Well this is a big disappointment as it makes using it from home impossible.
I've ordered another aerial as you need two for the mfj-1026 to work.
Might have to get my amateur licence at this rate.

Definitely don't rule out getting you amateur licence Jason. You get a massive chunk of radio spectrum to play with this is the HF allocation alone!

80 metres: 3.500 – 3.800MHz

60 metres: 5MHz (Full Licence only)

40 metres: 7.000 – 7.200MHz

30 metres: 10.100 – 10.150MHz

20 metres: 14.000 – 14.350MHz

17 metres: 18.068 – 18.168MHz

15 metres: 21.000 – 21.450MHz

12 metres: 24.890 – 24.990MHz

10 metres: 28.000 – 29.700MHz

C.B. sits between 12 & 10 meters.

So much more to play with and all protected by Ofcom!!!

You also get VHF, UHF and even microwaves!!!

If you want to explore the radio hobby further join a local club and go from there.

73's Gary.

JasonRees wrote:

Well this is a big disappointment as it makes using it from home impossible.
I've ordered another aerial as you need two for the mfj-1026 to work.

Cancel the order. The MFJ comes with a telescopic one and you can use anything, even just a random wire, as a receive antenna for the MFJ. It doesn't have to be resonant. The whole idea is it just receives noise from local sources and inserts those in out of phase to eliminate the QRM.

Amateur license is definitely worth it if you're into DXing. Whilst the 11m band is dead the 20m and 40m ones are still rocking with DX.

It was only £20 so I'm ok with it.
How long does it take to get the licence?