Scanner mounted within PC

[DylanMadigan]

Had this scanner connected to an actual server but kept having audio issues, possibly related to the USB audio adapter and VMWare Hypervisor.

SO, I've decided to use an old slimline PC that came with Vista (running 10 now). It's been working so now that I want to throw it on the server rack on a shelf, I decided to make it as professional as I could for now.

Essentially, that meant replacing the optical (CD) drive with the scanner. The tray already had holes in the right place and everything to do this. The power cable is spliced in with the computer's power so it comes on and off with the rest of the PC, and the audio cable just runs out the back and plugs into Line In.

I just have to put an antenna connection on the back so I don't have to run the cable direct to the scanner, and eventually I'd like to put a Motorola (or something) radio on here and have two way communication with this PC, but for now it is just a scanner feed.

 

[buddrousa]

You are putting a scanner in a high noise case that the pc case was designed to keep stray rf inside.

 

[KC9QFU]

You are putting a scanner in a high noise case that the pc case was designed to keep stray rf inside.

How do you figure the PC makes enough RF to make any kind of difference?

 

[buddrousa]

Working in a 2way shop with radios and pagers around pc's

 

[DylanMadigan]

He is right, I should mention that lol, plus the processor alone is putting off radiation at 1.9ghz but in my situation I just need it to pick up the repeater tower a block away, so the little bit of extra RF it's taking in does not affect it's clarity or ability to receive the desired signal.

If I wanted to do this with weaker signals I'd use sheet metal to make a shielded housing for the radio/scanner.

 

[buddrousa]

As you stated in your case it will work but I just wanted others to know the side affects of putting a scanner in a PC case.

 

[ka1njl]

Nice job! I once put an IC-PCR2500 in a computer. It is the same size as a 5.25” floppy drive and it had mounting holes in the right places. I even powered it from the pc’s power supply. It was compact and it worked like a charm.

 

[iMONITOR]

I like it! I always wanted to mount a Uniden BCD996 series in a top drive bay in a tower computer but the radio was a little too big.

 

[majoco]

These things....

WiNRADiO WR-G305i Receiver

...worked very well and there was very little self-generated or computer noise. The hard part these days is finding a computer with the right slots and a Com port! At the time they weren't cheap either

 

[phillydjdan]

I did something similar. I mounted a 536HP inside a PC case, but I added a surface mount NMO 800MHz whip and painted the case like a firetruck lol...

And the tower that scanner is receiving is only about 1/4 mile away, so noise is not an issue here, either.

 

[KC9QFU]

Working in a 2way shop with radios and pagers around pc's

I'm more familiar with computers than with radios, but there are lots of cases out there where they aren't really cases, but a place to mount all your equipment.

He is right, I should mention that lol, plus the processor alone is putting off radiation at 1.9ghz but in my situation I just need it to pick up the repeater tower a block away, so the little bit of extra RF it's taking in does not affect it's clarity or ability to receive the desired signal.

If I wanted to do this with weaker signals I'd use sheet metal to make a shielded housing for the radio/scanner.

Are you sure the 1.9 GHz isn't your CPU speed? If the CPU has that much RF, then you'll have other issues as well, such as audio bleed or bits getting flipped on your drives, plus just damaging your other hardware.

Do you guys have documentation to show this RF interference? I appreciate it.

 

[DylanMadigan]

Are you sure the 1.9 GHz isn't your CPU speed? If the CPU has that much RF, then you'll have other issues as well, such as audio bleed or bits getting flipped on your drives, plus just damaging your other hardware.

Do you guys have documentation to show this RF interference? I appreciate it.

1.9Ghz is the CPU speed/frequency, which to my understanding from school (Computer/Network Tech) means it will have measurable (though I'm not sure how much) amounts of radiation on that frequency. I'll see if I can find a PC i can play with and tune it's CPU to 2.4ghz, and use one of my modified wireless access points to measure the noise on the frequency, and see if it changes inside the PC.

As long as the system is just about completely wrapped with metal, it blocks most electromagnetic interference, which is why even the cheapest of cases still use aluminum alloy and not just plastic. This makes me wonder about gaming cases with the large clear glass/plastic sides, though im sure modern equipment gives off a weaker EMF.

 

[jim202]

I have a bunch of computers around my workshop. They run from a DOS only computers to 64 bit boxes with high clock speeds. What I have found is they will generate birdies on the VHF region and even into the UHF region. Each computer is different and the RF birdies are not on the same frequency between the computers.

What I have also found is that a good amount of the birdies and noise comes from the LAN cables and my 1 GB LAN speed. Some comes from un-shielded USB cables. Most of the USB cables you can get today are shielded. So the RF noise from them is limited. If you have a LAN hub or switch, they too will radiate RF noise. When I come into my driveway, one of the ham VHF radios will lock up on a particular ham repeater output from RF noise coming from the workshop. It bothers my radio from over 100 feet from the workshop. I don't listen to that repeater from home, so it becomes a moot issue for me.

Haven't found any problems with 6 meters or 10 meters from any of the RF noise generated by any of my computers. The HF bands are also clean from any computer generated noise. But we lost the local 6 meter repeater that was located on a tower in the back yard of a hospital. Thet noise floor became so high that the repeater could not hear anything. This is another reason that 6 meter repeaters around the country are no longer in service. I could point to all the 700 and 800 trunking systems that have been installed at many of the old 6 meter repeater sites. Think the problem comes from the micro possessors used in the control system of the trunking systems. But have never been able to shut a trunking system down to prove it.

So just be aware that there are many sources of RF noise around, including leaky cable TV systems. They are well known for RF leakage caused by poorly maintained cable connectors along their cable runs out on the street poles.

Jim

 

[prcguy]

The last thing I would want to do is put any receiving device in or near a computer. They are well documented to produce lots of RFI and I experience interference from computers all the time. At the very least you would want to RF bypass any connections to the radio like power, audio and use double shielded coax near the computer. Computers can induce RFI onto the shield of your coax, which gets carried up to the antenna then picked up. I would use good RF feedline chokes where the coax exits the computer and also near the antenna.

Before you commit to this take a handheld scanner tuned to some of your favorite frequencies then set it near the computer with the metal case removed. I'll bet you will find some frequencies that don't work so well when the computer is on and running. I have many frequencies that degrade quite a bit when my handheld scanner is near my computer with its case on.

 

[phillydjdan]

They used to say a PC power supply was bad to use for other electronics but now the voltages are far more stable, so unless someone has proof that PCs are RF nightmares I kinda have to shrug off the suggestion. They've come a long way in 20 years.

 

[buddrousa]

I use a commercial frequency counter and move around the case and pick up rf also my fire pager in monitor hears white noise near some PC's so it is proven to produce stray rf.

 

[prcguy]

Google "computer RFI" and you will see countless stories of problems and potential fixes, this is a widely known problem. "Stability" has never been a problem using computer power supplies with radio equipment, its the noise and that continues with current computers.

They used to say a PC power supply was bad to use for other electronics but now the voltages are far more stable, so unless someone has proof that PCs are RF nightmares I kinda have to shrug off the suggestion. They've come a long way in 20 years.