QRM across 27mhz in my area.

Hi,
26 CT 3427 here,
This is my first post, I hope it’s in the right section.
I’m coming back to CB and have had an interest in HF Comms and listening since I was a kid.
I’ve just being issued my CT call sign, thanks!!

I’m trying ideas for a home set up. The direction I want to go in is to have an “export” mobile unit like the President McKinley so I can be mobile, to take advantage of the North Downs nearby. But I really want to be home based the majority of the time.
I’m experimenting with my old Intek H520 plus with an after market antenna and using an old HF receiver with ssb using a BFO.

For years there’s been some external QRM which sounds like some kind of data right across the HF bands, it’s a annoying but still usable.

But since I’ve returned there is some terrible QRM affecting the HF bands, and one of the peaks is right on 27.515-555.
It does stop briefly then starts again. It doesn’t fade in or out, it starts and stops suddenly and is present 24/7 so maybe discount LED street lamps.

I’ve cut the power to the house and wandered around with the handled.
I can’t really find an area where it’s stronger, even going down the garden, so I’m presuming it’s in the wider area.

I’ve seen a YouTube clip from Fred in the Shed.
This is pretty much what I’m hearing.
https://youtu.be/mqikbz5b7dw
I hope it’s ok to link YouTube clips on here.

There is a solar panel on a roof about 200ft away but the QRM persists during the hours of darkness.

This could spell the end of my return to HF radio DXing
Any suggestions or comments would be great.
Cheers
Javelin Jim

Hi Jim
I am also experiencing the same up here in county Durham. The QRM is reading a good 7 on the signal meter on 27.555.
I was about to ask the same question to the forum
Paul

Hi. Jim.

Welcome to CTDX. I'm a afraid it's the sign off the times being in
Low & the Big 'C' everyone is on IT. either on-line shop/socialising
etc. + the Urban situation has been getting difficult for 12mths.
So I sold all my H/base gear & went portable uponthill. I can't do
that atm due to confined to Qth due to 'C' . I was getting S7-9 on
FM. S4-5 on T5 & S3 on 20/40 & S1/2 on 80. All can suggest is
get ur gear set-up & wait for EU 'E' due late April/May. The Hi will
be another 12mths.? p.s. my euip was FT 450d MFj Atu/Swr. V.
Inverted & Hygain AV18vs 80/10m. Good luck 73's Mike SW.

Hi Jim,

It's been this bad for a few years now as internet technology and use grows, but lessons are slowing being learned.

If you scan through the HF bands most, (but not all), of the amateurs bands are much cleaner than they ever have been. This has been in part due to complaints, investigations, etc. from organisations such as the RSGB, Ofcom and other radio organisations around the world applying pressure to relevant bodies. The International Telecommunications Union has incorporated measures to help avoid problems in the future. (Documents can be viewed on their site - ITU Regs.2019 - page 34 of the document outlines frequencies recognised for protection).

Unfortunately it doesn't cover CB frequencies!
(Or even SW broadcast frequencies but these have less commercial or otherwise interests in an internet age.)

I currently experience widespread RFI 'hash' which I've traced to BT telephone lines and the same QRM you've mentioned, (and linked on the Fred-In-The-Shed video), coming from the mains to the house.

You can be the proverbial dog chasing it's tail regards QRM tracing and elimination, believe you me I've been there

The old MW/AM transistor radio testing/RF 'sniffing' only shows you that every electronic/electrical device emits RFI. Move the radio slightly away from said devices and it drops quickly. They usually emit a squealing hash, (TV's, computer monitors, switch mode power supplies/chargers etc.), and unless close to your radio, antenna or antenna feed bear no resemblance to what is heard on air.
However, RF sniffing can pick up hash some 20 foot or so away from overhead BT lines(!) and the QRM you mention through mains wiring even with the mains switched off at your distribution box!

People do mention QRM-eliminators as a route, these can be expensive but also home built. I built an X-phase unit, it worked but only for one noise source at a time and took so much time and fiddling when scanning through the bands rendering it frustrating at best. It also reduces signals you're trying to receive!
(You can fiddle to your heart's content with these units for improvements but it is a royal pain.)

My solution?.......I put up with it. Listen me out on this one....

My radio room is located in an upstairs room at the front, right near offending BT lines. I moved my antenna feeds from exiting the front of the house to through the loft, (avoiding being near any mains wiring, the second offender), and exit the rear of the house. My HF dipoles run along the very top of the attic away from mains lines and my vertical dipole at the rear of the house.

This dropped my QRM considerably from the BT hash but I still had the mains borne noise to deal with, albeit at a lower level.
For this I simply press my NB, (noise blanker), button to the ON position

NB and ANL, (automatic noise limiter), do quite a good job at removing this noise.
You'll notice most videos showing this QRM are in AM mode and with any noise blanking turned off...makes for a more impressive video

You're quite right, the triple 5's are bad for DX weak signal but quite useable on sideband with noise blanking. The noise for me extends halfway through the UK FM band but luckily EU/CEPT, US/ mid-band are quite clean. So DX channels are still possible.


I've waffled on so forgive me I could've suggested a fortune in ferrites or other such, but I'd rather share my own limited successes.

You'll have less problems in a remote location.....then install internet, sky q, BT plug in wi-fi extenders, cheap LED lighting and introduce all that noise inducing technology to your new location

Or simply do your best and get back to enjoying radio.

I hope that helps you and any others with similar problems.


All the very best,
Victor

Hi Victor,
Thanks for the detailed reply.
I have overhead telephone wires at the front of the house.
I’ve been using the HF receiver in the loft with a 5.5m long wire antenna dangled out the window!....not very good st all but I’m trying in a very basic was to investigate wether the QRM is feasible to work with.
Today I’m going to try setting up in the back garden away from the house and the front where the phone wires are, to see where or if it’s worth me setting up a 1/2 wave antennae.
If the QRM is strongest where the radio is based but the antanae is less affected, will the radio itself be picking up the interference?

Cheers,
Jim

Hi,
I’ve experimented in the garden. I moved the heath Robinson receiver kit (Panasonic DR31 and a 5.5m wire taped to pole) about all over the garden but there doesn’t seem to any escape from it, even 100 foot from the house.
It’s between 25.110-26.850 and 27.525-27.875MHz, always there comes in stronger then drops off a little then strengthens again.
So it looks like the EU band is usable, which is ok but the 27.555 area is pretty much impossible at home.
So I could still set up a 1/2 wave in the garden but go mobile for the 555.
Cheers
Jim

Hiya Jim,

Well done on your experiments but don't give up so readily.
Forgive my waffling detailed reply earlier, I do like a gas and try to be thorough with information

I've been a SWL, (short wave listener), for more years that I care to mention and worked my way up from old Codar valve shortwave receivers to what at the time was the penultimate with the Lowe HF225. All was great until the noise started which only got worse over the years and caused my biggest gap in radio listening ever. I'd almost given up.
It was only on the loan of an old CB that my interest was ressurected and a short time with a President Lincoln that showed me what was possible and reintroduced me back to CB and eventually here to the Charlie Tangos.

With my interest towards a Ham licence a friend gifted me with his old Yeasu FT757GX. It had a few niggling faults that required attention including spending hours stripping and rebuilding the rotary encoder for the main tuning(!!!) But what a radio! With the work I mentioned earlier this has enabled me to go back to enjoying listening to the shortwave bands again. However the biggest improvement is the NB - noise blanking button. My old Lowe HF225 is however still afflicted as it has no such circuitry.
I'm afraid that neither does your Panasonic DR31.

I know it's a pain but there is always some workaround. As you mentioned you could go mobile, (when current restrictions are lifted), and many people have mentioned this as an improvement. However I am disabled with no car so cannot confirm this myself hence working harder on my homebase setup.

It's difficult to offer you further advice, it's up to you how far you take this hobby.
I know some people who have gone whole hog, bought an export radio, antenna, the lot, then left disappointed at no immediate contacts and given up selling on their gear. A real shame.
Others like myself have done all they can to pursue their interests and wait patiently for radio conditions to improve for CB DX. Yet others have been lucky to find local CB contacts and chat regularly & happily
Others still pursue their interests further becoming a Ham operator and then the world's your oyster

You can spend a lot and you can spend a little, both financially and/or timewise.

I hope you get to where you expect to be and wish you best of luck with it.


All the best,
Victor

Hi Victor.
I had a Lowe HF225..! An excellent piece of kit!
I used to listen the planes coming over the Atlantic giving their position, DX broadcast stations military and ham.
I used a longwire antenna.
That old Panasonic set of mine was my back up after I got the Lowe225. I ended up getting a larger HF receiver with all the bells and whistles on also a little Sony receiver with ssb.
I moved house and sold the lot. But I hung on to an old President Lincoln. That would’ve been perfect to get me started again.
Can I find it? Nope.
What I think is great about CB now, is the fact that there are enthusiast groups like this organising nets.
My missus can’t understand why I want to get back into it.
I explain that it’s not “plug n play” you’ve got to have some understanding of the hobby and it’s a challenge to get the kit running well.
So the issues I’m having are actually making me keen to push through them and do it...!

Cheers,
Jim

Hi Jim,

I've got say, you filled me with joy

I don't think everyone understands the passion that we can have surrounding radio and the interests therein. Whether it's a basic fascination for the 'magic' of radio, understanding the technology and becoming more involved or simply from the basic joy of what can be heard. I hear voices and languages from around the world, music from every culture, old Hams shooting the breeze and everything inbetween

CB radio is another aspect and as you say it has come of age from the old days, the enthusiasm today with groups like here and nets around the UK is outstanding.

As you mention, it's a bit more involved than modern 'plug-and-play' technologies and that's what makes it so fascinating.

My missus smiles when I say I'm off for a 'listen' and sits knowingly when I tell her stories of what I've heard. It's not her 'thing', but she does love that it makes me happy


Good for you Jim, glad you enjoy it all mate and it pushes you even when faced with challenges.

As already said, I wish you the very best with your ventures. Places like this bring like minded people together and all are happy to help where they can and when they can. I hope you find that Lincoln!


Kept my old Lowe because I love it....may even retro-fit a noise blanker so I can enjoy it again.


All the best to you Jim. I'll be sure to catch you about.
Victor

Javelin Jim wrote:

If the QRM is strongest where the radio is based but the antanae is less affected, will the radio itself be picking up the interference?

Cheers,
Jim  

Yes, no, possibly.

Yes:
If the antenna system isn't installed properly and you have an inadequate ground then the coax forms part of the antenna and you suffer common mode RFI. One of the downsides of that is higher susceptibility to interference on received signals.

No:
If the installation of the antenna system is done properly ensuring you have an adequate RF ground and using a RF choke at the antenna feedpoint to decouple the outer of the braid then no it shouldn't.

Possibly:
It is possible to install it properly but still pick it up if your power cable for example ends up inconveniently being the right length to act as a good antenna but winding a few turns around a mix31 toroid can mitigate that.

Thanks for the replies Victor and Northern Crusader.
Plenty of stuff to be thinking of...!
Well, I’ve taken the plunge, after messing about for the last few days with my HF receiver and a wire thrown over a tree! I’ve ordered a 1/2 wave silver rod, coax, connectors, power supply and an export modded set from Knights.
I should’ve kept all my stuff from 30 years ago!
I forgot about the basics.....using the RF gain to reduce the noise against a strong enough signal.
Listening to you guys and YouTube it seems that we’re all in the same boat as far as QRM is concerned.

Many thanks for the advice and I will be picking people’s brains all the more!

Cheers
Jim
26 CT 3427