Radio interference from class 331

[stephen_1234]

Hello,

I live about 100m from a railway line/station and I’ve had a radio interference problem from passing/stopping class 331’s for a couple of years (probably nothing changed since they were introduced).

I contacted Network Rail some time ago who were particularly helpful in ascertaining the reasons for it, and later Northern. However, both have been clear that the trains have been tested and passed all EMI requirements and nothing further can be done.

With that in mind, I wanted to make adjustments to my antenna based on some evidence that it would work (I don’t have that much free time to keep climbing trees/ladders), so I asked Northern for frequencies involved, radiation patterns, how it radiates (I presume it radiates via the overhead lines rather than the train itself), etc, in aim to learn more about it, but they were not willing to provide the information.

I ask here if any readers had similar amateur radio interference issue in relation to the class 331? What did you do to resolve it, besides move house? For example would investment in a vertical antenna instead of a long wire reduce it? I'm interested to learn more, if someone closer to the industry could offer some insight I'd be grateful.

Note that the 397s pass here and although they do produce a similar interference sound on a radio, it isn’t intense enough to ruin my hobby.

Thank you in advance.

 

[adc82140]

Is this something that OFCOM could help you with?

 

[zwk500]

You mention about amateur radio, which bands does your equipment work on? Would moving it to the far side/top of the house help?

 

[DanNCL]

As you mention 397s passing by, out of interest how do the occasional 802s compare for interference? As 80x units are known to have been problematic with electrical interference, and even with equipment to reduce it they still aren't great.

 

[Pete_uk]

I'm guessing a 25kv arc could create some RF noise!

 

[Recessio]

I'm guessing a 25kv arc could create some RF noise!

This was my thinking. Is it a problem from AC/OHLE power in general, rather than a specific component on a particular unit?

 

[stephen_1234]

Thank you for the replies.

In response (reverse order)-
1.
I'm not convinced that it's arcing, I'm familiar with that type of interference and it doesn't sound like it. I'd also note that the 319's pass here without any issue whatsoever. The sound is a oscillating "whine" increasing with intensity as the train arrives/leaves/passes, I can't really compare the sound to anything I've heard. I thought it might be the traction motors. It's not local to here either, by chance I heard the same interference on a car radio (usual MW band) as I approached a bridge in Wigan, the same where the line crosses the East Lancs road and around Eccleston (St Helens area).

2.
The 802's don't pass here and by what you said, I hope they never do!

3.
The frequencies concerned start at about 1000KHz in the MW broadcast band, gets progressively worse up to the 1.8Mhz band, and the 3.7Mhz band is affected, 7Mhz isn’t that bad. I don’t have a spectrum analyser so I couldn’t provide anything exact in this regard, only a perspective of my annoyance. I did move my antenna around the garden, higher, lower, even put one in the attic, all without success.

4.
Regarding OFCOM, they do have a process for dealing with it, but it’s quite a formal one with possible home visits etc, and don’t think my wife will tolerate it. I thought that a forum would be a more informal way of enquiring thoughts.

Additionally, with the December timetable change comes a more frequent service, good for me as a passenger, but would mean more frequent interference. I had a thought that if I share details of my problem that someone might know if the 331s are due for an upgrade (I’ve been checking the “Construction Updates” thread for a while) or if there is any likelihood that different rolling stock would get transferred for the Wigan-Liverpool route - Meaning I can either do nothing and the problem will resolve itself, or I need to find another solution.

Thank you again.

 

[AMD]

You'll be pleased to know that from the December timetable change most of the 331s are replaced by 319s!

 

[DaleCooper]

Have you tried an RF filter on the mains cable? It might be a long shot but as an experiment it should be quick and cheap.

 

[stephen_1234]

Sorry for the late response (busy weekend).

With regard to a mains filter: I'm convinced that the interference is coming through the antenna, I proved this by walking round my garden with a portable AM radio (the interference most pronounced around 1300-1600Khz), but no luck.

Regarding the 319s:
As a passenger I do prefer the 331s, they are much quieter, comfortable with big low windows, pram friendly etc, compared to the 319's which seem quite tired. So, I'm pleased and not pleased at the same time. I have a hope that the 331s would get updated at some point in the future, but as I am the only one affected (or cares enough to make enquiries about it), I don't think much will happen.

Thank you for all the replies.
Stephen

 

[DaleCooper]

I proved this by walking round my garden with a portable AM radio (the interference most pronounced around 1300-1600Khz), but no luck.

By "no luck" do you mean there was no interference on the portable radio?

 

[stephen_1234]

Hello,

"no luck" means no abatement of the interference. The internal ferrite antennas are directional, and interference is worse when the receiver is "directed" towards the railway line.

 

[Spekejunction]

Years ago in the days of Analogue Car radio a passing Pendalino completely blanked out my Radio reception..

 

[bangor-toad]

Hi,
Have you considered buying a Software Defined Radio USB adaptor? That will, with free software and a suitable antenna, give you a basic spectrum analyser. The frequency bandwidth isn"t huge per run but it could provide you with some info as to what frequencies are causing the worst issues & if you use a laptop you could map out where's worst.
There are lots available on Amazon or E-Bay. Expect to pay about £20 for a basic one.

Good luck,
Mr Toad

 

[stephen_1234]

Hello,

I wanted to let you know that since the timetable change the vast majority of trains stopping/passing have indeed been 319s, so generally interference free (and hopefully for a while). Thank you for the responses, it's appreciated.

Regarding an SDR - I did think about it and I'm still interested in what the spectrum would look like, but thought it's better to wait until the timetable change comes in before I spend any money.

 

[308165]

I've only just read this thread, which is most interesting.

I also live about 100m from a station served by 331s. About a year ago my home WiFi started to drop out fairly regularly. This hadn't happened previously, but I realised that it kept doing it when a 331 was in the station. At the time I thought it was something to do with the 331 WiFi but it could well be what you described above.

The issue does seem to have resolved itself now though.

 

[Trackman]

3.
The frequencies concerned start at about 1000KHz in the MW broadcast band, gets progressively worse up to the 1.8Mhz band, and the 3.7Mhz band is affected, 7Mhz isn’t that bad. I don’t have a spectrum analyser so I couldn’t provide anything exact in this regard, only a perspective of my annoyance. I did move my antenna around the garden, higher, lower, even put one in the attic, all without success.

This definitely sounds like a conduction related EMI as it's worse on 160m (top band 1.8Mhz), don't think a spectrum analyser will help.
Not teaching you to suck eggs or anything as I'm a ham too (only limited to 12m/10m 2m/70cms at the mo, but I'm a registered Ham for Hubnet for Dstar etc..).
First thing I say usually with RFI , is the radio properly grounded (spike in the ground), have you tried ferrite chokes? I guess you have.. plus you've tried a portable battery operated radio in the garden.. which is essential to test for mains RFI.
As I said this sounds like conducted EMI, best bet would be a good HF mag-loop antenna, but they are not cheap (my first purchase after lottery win!)
I'd google about it, best bet is to ask other hams and find out if there is a local amateur radio club in your area and contact them.

 

[stephen_1234]

Hello,

I think the spectrum emitted is more of an interest now, rather than a tool to cure the problem - I did notice "peaks" when tuning up the band when I first encountered the problem. I initially had a mind that the interference was an "image" due to the IF in the receiver. Since I went round my garden with a portable AM radio (slightly different IF) the frequencies concerned are the same so I am confident it's not an "image" problem.

The earth is a 4ft copper plated rod right (nothing special, I know you can buy solid copper ones but they are expensive)
The antenna is an inverted L type (didn't want a centre fed dipole), coupled via an impedance matching transformer (an "unun") to some good 50ohm co-ax. The braid is earthed (via earth rod) at receiver and antenna ends, and the co-ax is fed to the receiver about 15m away from the termination of the antenna, where the unun is.

Due to the 331s not running here so much since the timetable change, I'm not keen to start experimenting further unless something changes (hopefully not for a while).