Heavy interferences on frs radio caused by a printer

[Jack_Ofalltrades]

Hi gents and gals!

I was looking for some place to find radio knowledgeable persons to try to find some answers to a problem i have to deal with. We are using small frs radio as a mean to communicate in our expedition department. Our yard is not big, around 200 meter. The radio were working perfectly for a while. But we bought a new printer this summer and since then we hardly can communicate over more then 50 meter before the signal is so bad that nothing can be heard. I bought a GC EMF-390 to scan the room for possible interference i spotted some sources like the neon ballast and a battery charger. I unplugged all the possible culprit and the signal was as bad. When i scanned the printer with the meter hardly nothing at all coming from it. I tried to unplug the printer and after that i was back to be able to communicate with the radio normally.

So if no interference is coming from the printer up to the 10ghz that the meter can detect, and the printer is the problem, what could it be? There is large plate at the back of the printer, i was thinking may the plate absorb the signal? After i theorized that i measure the plate to see if it was possible for it to be the size to act as a big antenna tuned for the frs band but nope nothing close to it if it's even possible.

So i'm kinda stuck... I would greatly appreciate if someone could point me to possibilities that i could look for. I was expecting to find the source quickly and correct the situation but i now have more questions then answers... As often what look like the simplest of problem can be the most painfull to resolve...

Thank you and have a good day!

 

[MTS2000des]

Most likely the low spec subscriber units. Most FRS/GMRS bubble pack toy radios are based on low cost consumer grade system on chips, like the RDA1846 or similar, and without front end filtering, the presence of stray RF even way out of band, causes receiver overload and desense that higher quality subscriber radios are immune to.

You can spend the rest of your life trying to track down interference, or invest in higher quality commercial radios.

 

[mmckenna]

If everything worked fine until you installed the new printer, then the printer is causing enough interference to impact the FRS radios.

As MTS2000 said, they are often low quality radios, so it won't take a lot of interference to prevent them from working as they once did.

A few possible solutions:

Replace the printer. What ever you had there before wasn't causing the issue. Some electronics are just noisier than others.
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Move the printer. Since it's causing interference to the radios, try separating them. Move the printer farther away from where you use the radios. This is actually spelled out in the U.S. FCC Part 15 rules.
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Get better radios that will handle the interference better. That can get expensive, so don't assume that buying some cheap Chinese crap radios off Amazon is the solution.

 

[a417]

Is it a wireless printer, and are you using wireless to connect to it?

 

[Jack_Ofalltrades]

The radios are midland X-talker, i thought there were decent for the job i expected from them (be able to communicate over 200 meter...).

I understand it's probably a radio they pay top 20 dollars for and sell them a 40-50$ per unit though...

The printer will stay, this is a big commercial printer that's worth around 10k and is a very good model. We cannot move it out of the room it is in either...

It is connected byrj-45 so not using the wifi module on it, all printing job pass though the lan.

Buying better radio is an option, but how can i know if it will work or if i'm simply wasting money because the problem will affect the new one too? Do you have good model at a decent price range that you can recommend?

I have difficulty wrapping my mind around the fact that the printer does not seem to emit nothing at all with a meter that get all range up to 10ghz... I know it's not a professional meter but still a quality instrument...

 

[IC-R20]

UHF can very much be affected by noise interference as well even on a decent front-end. I used to have to a computer monitor that emitted a really strong narrowband signal that only picked up on channel 17, I could even see it on the spectrum analyzer. Though more rare than on VHF there are some things that generate noise higher up the bands.

 

[vagrant]

Do some testing by wrapping tinfoil onto a large piece of cardboard as tall and wide as the printer. Operate the radios as you normally do while moving the panel to each side of the printer. If you find a position that blocks/reduces the interference, purchase a standard free standing office equipment panel and get creative with copper or foil inside and place the fabric back on. Alternatively, purchase some Faraday fabric and simply drape it over an office partition or partitions if the interference is really problematic and needs to be blocked from more than one side of the printer.

 

[wtp]

i used to work in a lumber yard and had wall insulation that was 1 inch by 4 feet by 8 feet.
when it was delivered they had sacrificial pieces with small holes in it or was damaged.
we would throw them away.
so maybe try a lumberyard for some 'garbage' pieces...

 

[madrabbitt]

printers, especially laser printers, are noisy as heck, and its all electrical noise. They are also a dick to clean power. I had a laser printer in my office that would reboot all the UPS's every time it power cycled. Needless to say, its not in my office anymore.

dont point the service monitor at the printer, point it at the cord, to the wall, and along the wall on either side of the outlet its plugged into. Chances are you'll see noise there. You'll probably also see noise in random parts of the electrical grid.

On that subject, surrounding the printer body itself with attenuating material probably wont solve the issue. Not using the printer wont solve the issue either, and even if you COULD move it somewhere else in the office, theres going to be random noise on the grid no matter what.


Am i understanding correctly that most of the radios are outside, and cant talk back in to ones in the office?
Are they still working normally outside talking to each other?

 

[amcferrin90]

FWIW my Moto 7550's will pick up birdies from my PC when it's between BIOS boot and Windows start. Likely something in the GPU maybe. So don't just discount it as cheap radios.

 

[chief21]

It's not at all unusual to find that office electronics can often interfere with communications equipment. Some office electronics emit strong, relatively narrow signals at one (or more) discrete frequencies, while others can "broadcast" less powerful signals over a much wider range of frequencies. Depending on the circumstances at hand, either scenario can disrupt radio communications.

If you're unable to move the printer, one possible solution might be to utilize a small FRS/GMRS desktop radio (as a base station), connected to an external antenna placed well away from the printer location.

 

[krokus]

I saw mention, but not a specific question: does this affect all the channels, or just the channel you usually use?

 

[Jack_Ofalltrades]

From all i've read since my last message, i have a lot to test. I'll test if the radio can communicate well from outside the office, i will try to change channel to see if other channel are affected too, i will test if i can get interferences with my emf/ef/rf meter near the wire or the receptacle too. From all your inputs i was also thinking of dusting off my SDR to use as spectrometer to maybe catch if i have a peak somewhere. I'll need to find it first...

Most of the radios are inside, and we have our yard worker that is unable to communicate with them anymore. But i never tested if the radio from the other depatments were working properly or not,i focused at the problem of the expedition dept and got tunnel vision it looks like.

Madrabitt : Yes its a laser printer. In the case is it electrical, would something like an isolation transformer could help reduce transmission of the noise to a minimum? Could it be something i could see if i scope the second outlet from the same receptacle as the printer? Do you know what to look for precisely?

A base station with an external antenna could be a very good solution if all else is working properly and the problem is only localised in the exp dept.

Thank you all for the help, i will test all those things and post the results!

 

[K6GBW]

If this printer is generating noise only near the frequencies used by the FRS radios you might try a different type of radio. I'm thinking switch to MURS? Obviously you'd want to test those first. Another option, and one that is pretty immune to most noise is the Motorola DTR series radios. They have the benefit of being much more secure as well.

 

[Jack_Ofalltrades]

If this printer is generating noise only near the frequencies used by the FRS radios you might try a different type of radio. I'm thinking switch to MURS? Obviously you'd want to test those first. Another option, and one that is pretty immune to most noise is the Motorola DTR series radios. They have the benefit of being much more secure as well.

Noted! Thank you! I'll make my tests thursday evening.

 

[K3YGX]

Have you tried ferrite beads on the power cord?

 

[ecps92]

Have you tried ferrite beads on the power cord?View attachment 153278

Don't just consider the power cord, but also any other connections (USB and Network cables)

 

[K6GBW]

Honestly, if this printer is causing THAT much interference then something is wrong. Regulations prohibit devices that make more than small amounts of noise. Are you SURE that printer is the problem? I had an LED light that absolutely destroyed my HF radio reception. Maybe just unplug the printer as a fast test to be sure you're working on the right problem.

 

[ArkTex]

Have you thought about getting a commercials license for business band? Maybe that would be better than using FRS/MURS. It's sounding like this is being used in a commercial environment.

 

[merlin]

I get considerable noise on channel 3 and 22. enough so that weaker signals garble voices. Perhaps trying quieter channels will help.
If that prinner is the source, those ferrite beads (post # 16) on all of the external wiring, close to the printer, should help.