[Misc] Machine causing static on handheld radio

[bilyahn]

We just replaced a Sharp MX-M453N with a Sharp MX-M565N at the county jail. When the officers get close to it with their handheld Motorola radios it causes the radios to emit a static noise. The old machine did not do this. When we turn the machine off the problem goes away. I took the power filter off and the problem went away but has since returned. We also made sure the machine is not in wifi mode. I have been in the industry for 33 years and this is a first for me. I'm not even sure how to go about troubleshooting a problem like this on so any ideas, no matter how crazy they sound, will be greatly appreciated.

[NeoMatrix]

Re: Machine causing static on handheld radio

We just replaced a Sharp MX-M453N with a Sharp MX-M565N at the county jail. When the officers get close to it with their handheld Motorola radios it causes the radios to emit a static noise. The old machine did not do this. When we turn the machine off the problem goes away. I took the power filter off and the problem went away but has since returned. We also made sure the machine is not in wifi mode. I have been in the industry for 33 years and this is a first for me. I'm not even sure how to go about troubleshooting a problem like this on so any ideas, no matter how crazy they sound, will be greatly appreciated.

455khz IF (intermediate frequency) coming from the copier main board crystal oscillator.
The IF will be interfering with the hand held radios IF mixer stage frequency.

It is known that transmitting in the 455khz range can force a heterodyne transceiver to hear unwanted signals. Some people flip out and believe god or the devil is communicating to them through their radio or mobile phones and digital television.

Hackers can and do interfere with set forms of communications using the known I.F. signals.

I have people come up to me an ask how come I received an SMS message on my mobile phone from no sender or empty/blank number ID field ? They have a full message sent from no person or phone number. They ask me "how does that happen?" I've witness 4 or 5 of these same mobile phone events from different people I've come into contact with. I'm thinking about passing those mobile phone events onto the AFP.

The world is moving at a fast pace. Technology is moving faster.



-------------------- insert --------------------------------------
Commonly used intermediate frequencies[edit]

• 110 kHz was used in Long wave broadcast receivers.^[1]:159
• Analogue television receivers using system M: 41.25 MHz (audio) and 45.75 MHz (video). Note, the channel is flipped over in the conversion process in an intercarrier system, so the audio IF frequency is lower than the video IF frequency. Also, there is no audio local oscillator, the injected video carrier serves that purpose.
• Analogue television receivers using system B and similar systems: 33.4 MHz. for aural and 38.9 MHz. for visual signal. (The discussion about the frequency conversion is the same as in system M).
• FM radio receivers: 262 kHz, 455 kHz, 1.6 MHz, 5.5 MHz, 10.7 MHz, 10.8 MHz, 11.2 MHz, 11.7 MHz, 11.8 MHz, 21.4 MHz, 75 MHz and 98 MHz. In double-conversion superheterodyne receivers, a first intermediate frequency of 10.7 MHz is often used, followed by a second intermediate frequency of 470 kHz. There are triple conversion designs used in police scanner receivers, high-end communications receivers, and many point-to-point microwave systems.
• AM radio receivers: 450 kHz, 455 kHz, 460 kHz, 465 kHz, 467 kHz, 470 kHz, 475 kHz, 480 kHz.^[10]
• Satellite uplink-downlink equipment: 70 MHz, 950-1450 MHz (L-Band) Downlink first IF.
• Terrestrial microwave equipment: 250 MHz, 70 MHz or 75 MHz.
• Radar: 30 MHz.
• RF Test Equipment: 310.7 MHz, 160 MHz, 21.4 MHz.

[SwisSeV]

Re: Machine causing static on handheld radio

You are getting radio frequency interference. The cause might be hard to find, but if you really want to go down the rabbit hole you need to be prepared. It's possible the interference was made worse by someone taking the machine apart and not putting it back together properly (with all the shielding)? It might also help to figure out what frequency is getting the interference so that you can narrow down your search a little bit.

[brewster67]

Re: Machine causing static on handheld radio

Ran into this with a MX4101 that we installed in the same building with a fire dispatch center. They would get background noise on the radio when the copier was on. We spent a lot of time with their radio tech. tracking the problem. Found that multiple MX4101's would do it and MX5001 had same problem. A MX3610 they had caused no interference with the radio. After some trial an error found that if you unplugged the HL pwb (fuser lamp board) from the AC pwb the noise disappeared. Contacted Sharp and was directed to the warning in the user's manual

NOTE
This equipment has been tested and found to comply with the limits for a Class A digital device, pursuant to Part 15 of the FCC Rules.
These limits are designed to provide reasonable protection against harmful interference when the equipment is operated in a commercial
environment. This equipment generates, uses, and can radiate radio frequency energy and, if not installed and used in accordance with
the instruction manual, may cause harmful interference to radio communications. Operation of this equipment in a residential area is likely
to cause harmful interference in which case the user will be required to correct the interference at his own expense.

So basically Sharp said we know it may happen and if it does there is nothing they can do.

We never really solved the problem just got lucky that they were do for some upgrades to the radio system and antenna. After the upgrade they quit complaining about the interference.

The only things I see that you can try is to have them change frequency on their radio or try a different machine.

[NeoMatrix]

Re: Machine causing static on handheld radio

The only things I see that you can try is to have them change frequency on their radio or try a different machine.

I believe that changing frequencies on the hand held radio probably won't make any difference to the static heard. The offending frequency is most likely sitting in range of the 455Khz I.F. mixer stage, or a harmonic frequency thereof.

Re: Copier fuser board
Oscillations from the fuser lamp board could be causing RF sperry in the 455khz range, or even a harmonic frequency as high as 10mhz?
There could be a hot plasma RF effect coming from some type of cavity resonance inside the fuser hot roller. I don't really know.

I'm incline to believe that a good power point earth stake driven into the ground outside the building with a good earth to the copier might fix the floating ground RF sperry on the copier. Which obviously should fix the hand held radio static.

[blackcat4866]

Re: Machine causing static on handheld radio

Thanks for the education Neo. I noticed it on the two-way Motorolas that we used for a while in the late 90's, but did not know the cause. Specifically certain telephones would cause my two-way to flip out, and start clicking and buzzing and snapping. On one memorable occasion one of our techs was talking on his two-way, and it crossed over to the customers intercom, and broadcast his entire conversation throughout a very large plant. He was not using his good-company vocabulary either. =^..^=

[ZOOTECH]

Re: Machine causing static on handheld radio

Thanks for the education Neo. I noticed it on the two-way Motorolas that we used for a while in the late 90's, but did not know the cause. Specifically certain telephones would cause my two-way to flip out, and start clicking and buzzing and snapping. On one memorable occasion one of our techs was talking on his two-way, and it crossed over to the customers intercom, and broadcast his entire conversation throughout a very large plant. He was not using his good-company vocabulary either. =^..^=

That is so funny!

[NeoMatrix]

Re: Machine causing static on handheld radio

That is so funny!

In our youth we had a tad of fun with CB radios going through Pizza Hut and KFC drive through speakers.

Sitting in line at the KFC drive through waiting to order.

Car in Front : That will be all thanks...

CB Op: And was there flies with that order....

Car in front : No!!! I said no fries.

CB Op: There are No Flies in our orders....

KFC Op : Sorry sir someone went past with a CB radio, can you repeat the last order....

[nottoosharp]

Re: Machine causing static on handheld radio

What about a faraday?


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[qbert69]

Re: Machine causing static on handheld radio

Take a portable AM/FM handheld radio...use in AM mode....if the noise is fairly broadband, you'll be able to sweep the antenna near the noise and hear it on the AM radio! If you don't have a line noise/surge filter, you might try one of those! Also, you can get cut to size pieces of copper screen that can be used as a shield which can then be shunted to ground to reduce/eliminate noise!

Cheers!

[qbert69]

Re: Machine causing static on handheld radio

In our youth we had a tad of fun with CB radios going through Pizza Hut and KFC drive through speakers.

Sitting in line at the KFC drive through waiting to order.

Car in Front : That will be all thanks...

CB Op: And was there flies with that order....

Car in front : No!!! I said no fries.

CB Op: There are No Flies in our orders....

KFC Op : Sorry sir someone went past with a CB radio, can you repeat the last order....