Any Good Sources For Shielded USB 2 and 3 Cables With Ferrite Cores?

[Merovingian]

I'm finally about ready to connect my SDR radios to my PC. I have an Ettus B200, an RSPDuo and a Airspy HF+ Discovery.

I've had my RSPDuo for several months but just now, stupidly realized, that it didn't come with a USB cable. This is one reason I am searching for better USB cables for this and my other SDRs so I can hopefully avoid any noise and interference from my PC getting into my radios.

The best I have seen have have ferrite chokes on each end. I don't know if they are shielded or not, maybe all decent USB cables are already shielded anyway. . . .

It looks like the B200 uses a USB 3.0 A to Micro B (that weird looking wide, flat connector)
The RSPDuo looks like it uses a USB 2.0 A to B cable
The Airspy HF+ Discovery looks like it uses a USB 2.0 A to Micro B

One site I found Chroma Cables: Audio Optimized USB Cables Seems to have the USB 2.0 A to B cables but I didn't see the other two types I need.

Any one know of other good sources to buy USB shielded cables with Ferrite chokes at each end?

Also, any advice for eliminating noise in the cable? Bigger chokes? More of them?

I also wanted to get some USB to fiber optic converters but they are pretty expensive so I guess I won't go that route.

Thanks for your help.

 

[phask]

Offhand, no. There is a company that advertises in CQ, but I do not have a paper copy. They probably have ANYTHING that you need.

 

[prcguy]

I would get a generic USB cable longer than you need and apply your own ferrites. At the most I have only seen one ferrite bead at each end of a USB cable and that does basically nothing for RF EMI traveling on the outside of the cable. A single run through a ferrite bead give you maybe 150 ohms of choking impedance and you want several thousand or more ohms and you want it at each end of the cable.

Each time you double the number of turns through the ferrite the inductance goes up four times, so a single pass of 150 ohms becomes 300 ohms with two turns and 600 ohms with four turns, etc. The ferrites you usually find on factory cables are typically #43 mix which favor the VHF/UHF bands and if you want to snuff out noise in the HF bands you want a different mix like 31.

For my SDR USB cables I use a large #31 mix snap on ferrite bead with a roughly 1/2" hole and pass six turns through them to target the HF bands. This is also effective on VHF/UHF but a #43 mix would be better for that giving up some on HF.

 

[mmckenna]

Have you tried Monoprice? They've got a pretty good selection, and you can search based off each connector end.

There's several with torroids if you want those.

And as far as I know, all the USB type cables I've seen have a shield. I'd hesitate to say they all do, because I'm sure some cheap Chinese stuff doesn't.

 

[Merovingian]

Really? So the choke on the cable mostly does nothing. . .

That is some good information. . .

Where should I look to buy #31 and #43 beads? I know I can probably search for myself of course but hitting the "bullseye" of sources is time saving.

Do I need the ferrite on both ends of the cable? Or just one?

How about cable length? I figured a shorter cable ~1m or so is usually best but I have read of some people buying longer cables to get their radios further away from their computers. I would think a longer cable at a certain point would start to degrade the data transfer.

Would you mind pointing me to some example pictures of the best way to wind the cables arround the choke?

How about if I got a really big choke and wrapped 10-12 turns or something? Is more than six turns just more trouble and giving diminishing returns?

Thanks again.

I would get a generic USB cable longer than you need and apply your own ferrites. At the most I have only seen one ferrite bead at each end of a USB cable and that does basically nothing for RF EMI traveling on the outside of the cable. A single run through a ferrite bead give you maybe 150 ohms of choking impedance and you want several thousand or more ohms and you want it at each end of the cable.

Each time you double the number of turns through the ferrite the inductance goes up four times, so a single pass of 150 ohms becomes 300 ohms with two turns and 600 ohms with four turns, etc. The ferrites you usually find on factory cables are typically #43 mix which favor the VHF/UHF bands and if you want to snuff out noise in the HF bands you want a different mix like 31.

For my SDR USB cables I use a large #31 mix snap on ferrite bead with a roughly 1/2" hole and pass six turns through them to target the HF bands. This is also effective on VHF/UHF but a #43 mix would be better for that giving up some on HF.

 

[Merovingian]

I briefly looked at Monoprice but didn't know how good they were and it looked like they didn't have chokes on both ends. It sounds like those chokes may not be all that great anyway. I'll have to go back and give them a second look.

Have you tried Monoprice? They've got a pretty good selection, and you can search based off each connector end.

There's several with torroids if you want those.

And as far as I know, all the USB type cables I've seen have a shield. I'd hesitate to say they all do, because I'm sure some cheap Chinese stuff doesn't.

 

[mmckenna]

I briefly looked at Monoprice but didn't know how good they were and it looked like they didn't have chokes on both ends. It sounds like those chokes may not be all that great anyway. I'll have to go back and give them a second look.

I've had a good experiences with anything I've purchased from them. They are usually cheaper than just about anyone else. Usually I'm only buying things like USB or USB-Lightning type cables.

I'd absolutely defer to PRCGUY about the toroids, that's definitely not my area of expertise.

 

[phask]

Amazon has various chokes/beads. I've used them a few times.

 

[KK4JUG]

I needed a 3' audio XLR snake and Monoprice was the only place I could find it. Got it quick and it's great quality for only $7. I was impressed.

 

[prcguy]

Here is a picture of the cable I use with my RSP2pro when traveling. Its got 5 turns through a 31 mix ferrite on one end for HF and three turns around a special mix for VHF/UHF on the other end. My goal was six turns on the 31 ferrite but only five would fit. I believe this is the 31 mix ferrite I used: 2x31-7281p2

There is a specific amount of turns on a specific size and mix ferrite to target a frequency range. I get some of this information from the Internet and some I determine by testing.

Really? So the choke on the cable mostly does nothing. . .

That is some good information. . .

Where should I look to buy #31 and #43 beads? I know I can probably search for myself of course but hitting the "bullseye" of sources is time saving.

Do I need the ferrite on both ends of the cable? Or just one?

How about cable length? I figured a shorter cable ~1m or so is usually best but I have read of some people buying longer cables to get their radios further away from their computers. I would think a longer cable at a certain point would start to degrade the data transfer.

Would you mind pointing me to some example pictures of the best way to wind the cables arround the choke?

How about if I got a really big choke and wrapped 10-12 turns or something? Is more than six turns just more trouble and giving diminishing returns?

Thanks again.

 

[Merovingian]

Ahhhh okay. . . Interesting. A little different than I thought it would look. Thanks for the picture!

I was thinking it was going to look something like this:



Your version seems more compact.

Have you noticed if having your SDR closer or farther away from your PC makes any difference at all? Or is having the ferrite bead on it solving the problem?

About how long is your USB cable? 8 feet? 10 feet?

Thanks again for all of your help. I'm going to check out the link you posted. You have probably saved me from some head aches with thinking that a USB cable with a built in choke was solving all of my problems when it was really not doing much at all.

Here is a picture of the cable I use with my RSP2pro when traveling. Its got 5 turns through a 31 mix ferrite on one end for HF and three turns around a special mix for VHF/UHF on the other end. My goal was six turns on the 31 ferrite but only five would fit. I believe this is the 31 mix ferrite I used: 2x31-7281p2

There is a specific amount of turns on a specific size and mix ferrite to target a frequency range. I get some of this information from the Internet and some I determine by testing.

View attachment 78298

 

[Merovingian]

Looking at the materials in the link you sent, it looks like I might do good with a bead of 75 material and a second bead of 28 material. That would cover me from 200kHz to 1 GHz.

Here is a picture of the cable I use with my RSP2pro when traveling. Its got 5 turns through a 31 mix ferrite on one end for HF and three turns around a special mix for VHF/UHF on the other end. My goal was six turns on the 31 ferrite but only five would fit. I believe this is the 31 mix ferrite I used: 2x31-7281p2

There is a specific amount of turns on a specific size and mix ferrite to target a frequency range. I get some of this information from the Internet and some I determine by testing.

View attachment 78298

 

[prcguy]

Those materials might be ok but you would need to know how many turns will give the desired results.

Looking at the materials in the link you sent, it looks like I might do good with a bead of 75 material and a second bead of 28 material. That would cover me from 200kHz to 1 GHz.

 

[Merovingian]

Ahh okay. Six turns doesn't work in every situation. . .

How would I figure that out?

Those materials might be ok but you would need to know how many turns will give the desired results.

 

[prcguy]

I have charts I can share for the FT-240 series of toroid rings in various mixes similar to your post #11 but not for the snap on types. I started with a recommended size and mix for bypassing HF screwdriver motor wiring then made a test jig for a scalar network analyzer and did my own testing. I think my smaller VHF/UHF choke is a 28 mix.

Ahh okay. Six turns doesn't work in every situation. . .

How would I figure that out?

 

[Merovingian]

Oh okay, you really did your own homework. Sure, if you have a chart you can share I would appreciate it.

I'm looking into getting a network analyzer, hopefully this next year. I'll have to wait until then to do some testing. I guess I'll have to do some trial and error testing in the meantime when I get all of my cables and chokes.

I have charts I can share for the FT-240 series of toroid rings in various mixes similar to your post #11 but not for the snap on types. I started with a recommended size and mix for bypassing HF screwdriver motor wiring then made a test jig for a scalar network analyzer and did my own testing. I think my smaller VHF/UHF choke is a 28 mix.

 

[Merovingian]

I've ordered my USB cables from Monoprice and my Ferrite chokes from Amidon. I ordered 6 foot USB cables so I figure I'll wrap the ferrite beads as many times as I can fit to see how that does. . . if it does anything at all. . .

With the Christmas holiday here I probably won't get anything until early next week.