Topics

USB cable quality and QRM in a spyserver setup with an Airspy Hf+ and Raspberry PI3. 6 microUSB cable test. #airspyhfplus #bestpractice #raspberrypi

ea5ehs@...
 

Last February I got surprised for the QRM emitted from USB cables at the remote RX site when performing the initial setup of the SDR.

In the remote RX site, I replaced the nice working Red Pitaya SDR (Soft from Pavel Demin) with the Airspy HF3 + Raspberry PI 3B configured as a spyserver.

I soon discovered a really bad noise floor and began checking with my Swiss army tool "Tecsun PL600".
RF emission in VHF/HF from the RPi3, SDR, and cables was unacceptable. The culprit was traced to the USB cable connecting between the Rpi3 and the Airspy HF+. 
Using all the USB cables available on the site and my car, I improvised a USB cable comparison test in HF and VHF whose results can be found attached to this post ( 3.2MB pdf file, I have never published before). 

This is an unscientific test because it was improvised, please don't blame me for any inconsistency in the results. I had to quit testing after 2 hours because I couldn't cope with the cold and windy conditions (QTH is 950m ASL).
Conclusion: Good quality USB cables are a must in RX QTH.

I wish this can be useful and/or inspiration to others.

My best 73 all
from Niceto
EA5ZL

David Ranch
 


Hello EA5ZL,

Thanks for taking the time to write this up and it's quite illuminating to see how poor some of those cables are.  I too have run into cables that LOOK like their quality made with built-in ferrites on both ends, etc. only to find their crap.  I wish we could find a reliable source of "RF tight" cables that both consistently good and aren't outrageously priced.

Anyway.. I look forward to your results on the OrangePi to see if it's any better.  Btw.. why the OrangePi vs. say a Tinkerboard or a Pine64 or other?  There are SO many SBCs out there now but it's impossible to beat the community and support found with the Raspberry Pi boards.

--David
KI6ZHD

ea5ehs@...
 

Hello David,
I decided to go de Orange Pi UNO way for different reasons; low cost, Gigabit ethernet outside the usb bus, only one usb 2.0 port. 
My theory about the usb qrm from cables is that there is a RPI USB design allowing for this. I have tested one Rpi2B and two Rpi3B with identical results.
QRM is only generated when an active data connection is on, ie when a client connects to spyserver and start sdr#. 
When I connect the airspy HF+ to a usb port of my Laptop and rin SDR#, no noise is generated with any of the six tested cables' using the same antennas.
I was considering the Tinkerboard SBC but as I'm runing on solar power, every mW  of power consumption counts. Tinkerboard seems to draw more power than Rpi an Orange pi. Rpi3+airspy accounts for 630mA at 5V during an active connection. I have also taken additional power saving measures like turning off the on Board leds and the HDMI.

Best Ni
EA5ZL

D R
 

Hi David,

I'm currently using Wolfblitz shielded cables I bought on Banggood, and I've found them to be very good indeed.  I've been running an ELAD S2, an RSP1A and an HF+ simultaneously without a trace of PC/USB noise on any of them, whereas previously it took a ton of ferrite to get rid of about 90% of it - on supposedly "good quality" cables.  No ferrite is needed on the new cables.

I think they are only made with microUSB or Type-C connectors at the device end, so I had to get a couple of microUSB to Type B adapters for the S2 and RSP1A, but they don't appear to have compromised the end to end shielding.  They aren't expensive when bought direct, and are well worth a look.

Regards,
Dave



From: David Ranch <airspy-groupsio@...>
To: main@airspy.groups.io
Sent: Sunday, 11 March 2018, 16:44
Subject: Re: [airspy] USB cable quality and QRM in a spyserver setup with an Airspy Hf+ and Raspberry PI3. 6 microUSB cable test. #airspyhfplus #bestpractice #raspberrypi


Hello EA5ZL,

Thanks for taking the time to write this up and it's quite illuminating to see how poor some of those cables are.  I too have run into cables that LOOK like their quality made with built-in ferrites on both ends, etc. only to find their crap.  I wish we could find a reliable source of "RF tight" cables that both consistently good and aren't outrageously priced.

Anyway.. I look forward to your results on the OrangePi to see if it's any better.  Btw.. why the OrangePi vs. say a Tinkerboard or a Pine64 or other?  There are SO many SBCs out there now but it's impossible to beat the community and support found with the Raspberry Pi boards.

--David
KI6ZHD



Patrick
 

Hi Dave,

Could you please provide the reference of the shielded cable you mention ?
Thanks.

2018-03-11 21:39 GMT+01:00 D R via Groups.Io <robsond90@...>:

Hi David,

I'm currently using Wolfblitz shielded cables I bought on Banggood, and I've found them to be very good indeed.  I've been running an ELAD S2, an RSP1A and an HF+ simultaneously without a trace of PC/USB noise on any of them, whereas previously it took a ton of ferrite to get rid of about 90% of it - on supposedly "good quality" cables.  No ferrite is needed on the new cables.

I think they are only made with microUSB or Type-C connectors at the device end, so I had to get a couple of microUSB to Type B adapters for the S2 and RSP1A, but they don't appear to have compromised the end to end shielding.  They aren't expensive when bought direct, and are well worth a look.

Regards,
Dave



From: David Ranch <airspy-groupsio@...>
To: main@airspy.groups.io
Sent: Sunday, 11 March 2018, 16:44
Subject: Re: [airspy] USB cable quality and QRM in a spyserver setup with an Airspy Hf+ and Raspberry PI3. 6 microUSB cable test. #airspyhfplus #bestpractice #raspberrypi


Hello EA5ZL,

Thanks for taking the time to write this up and it's quite illuminating to see how poor some of those cables are.  I too have run into cables that LOOK like their quality made with built-in ferrites on both ends, etc. only to find their crap.  I wish we could find a reliable source of "RF tight" cables that both consistently good and aren't outrageously priced.

Anyway.. I look forward to your results on the OrangePi to see if it's any better.  Btw.. why the OrangePi vs. say a Tinkerboard or a Pine64 or other?  There are SO many SBCs out there now but it's impossible to beat the community and support found with the Raspberry Pi boards.

--David
KI6ZHD




D R
 

Hi Patrick - I got the name wrong: it's BlitzWolf, not Wolfblitz!!  Just search for

BlitzWolf AmpCore Turbo BW-MC8 2.4A Braided Durable Micro USB Charging Data Cable 6ft/1.8m

and they'll pop straight up.  I bought three @ 1.8m and two @ 1m, and delivery took 8-10 days.  (Just make sure you don't order Type-C by mistake!)

Regards,
Dave



From: Patrick <aunumero73@...>
To: main@airspy.groups.io
Sent: Sunday, 11 March 2018, 20:45
Subject: Re: [airspy] USB cable quality and QRM in a spyserver setup with an Airspy Hf+ and Raspberry PI3. 6 microUSB cable test. #airspyhfplus #bestpractice #raspberrypi

Hi Dave,

Could you please provide the reference of the shielded cable you mention ?
Thanks.

2018-03-11 21:39 GMT+01:00 D R via Groups.Io <robsond90@...>:
Hi David,

I'm currently using Wolfblitz shielded cables I bought on Banggood, and I've found them to be very good indeed.  I've been running an ELAD S2, an RSP1A and an HF+ simultaneously without a trace of PC/USB noise on any of them, whereas previously it took a ton of ferrite to get rid of about 90% of it - on supposedly "good quality" cables.  No ferrite is needed on the new cables.

I think they are only made with microUSB or Type-C connectors at the device end, so I had to get a couple of microUSB to Type B adapters for the S2 and RSP1A, but they don't appear to have compromised the end to end shielding.  They aren't expensive when bought direct, and are well worth a look.

Regards,
Dave



From: David Ranch <airspy-groupsio@...>
To: main@airspy.groups.io
Sent: Sunday, 11 March 2018, 16:44
Subject: Re: [airspy] USB cable quality and QRM in a spyserver setup with an Airspy Hf+ and Raspberry PI3. 6 microUSB cable test. #airspyhfplus #bestpractice #raspberrypi


Hello EA5ZL,

Thanks for taking the time to write this up and it's quite illuminating to see how poor some of those cables are.  I too have run into cables that LOOK like their quality made with built-in ferrites on both ends, etc. only to find their crap.  I wish we could find a reliable source of "RF tight" cables that both consistently good and aren't outrageously priced.

Anyway.. I look forward to your results on the OrangePi to see if it's any better.  Btw.. why the OrangePi vs. say a Tinkerboard or a Pine64 or other?  There are SO many SBCs out there now but it's impossible to beat the community and support found with the Raspberry Pi boards.

--David
KI6ZHD






Patrick
 

Thanks for the tip Dave ;-)

Regards,
Pat

2018-03-11 21:54 GMT+01:00 D R via Groups.Io <robsond90@...>:

Hi Patrick - I got the name wrong: it's BlitzWolf, not Wolfblitz!!  Just search for

BlitzWolf AmpCore Turbo BW-MC8 2.4A Braided Durable Micro USB Charging Data Cable 6ft/1.8m

and they'll pop straight up.  I bought three @ 1.8m and two @ 1m, and delivery took 8-10 days.  (Just make sure you don't order Type-C by mistake!)

Regards,
Dave



From: Patrick <aunumero73@...>
To: main@airspy.groups.io
Sent: Sunday, 11 March 2018, 20:45
Subject: Re: [airspy] USB cable quality and QRM in a spyserver setup with an Airspy Hf+ and Raspberry PI3. 6 microUSB cable test. #airspyhfplus #bestpractice #raspberrypi

Hi Dave,

Could you please provide the reference of the shielded cable you mention ?
Thanks.

2018-03-11 21:39 GMT+01:00 D R via Groups.Io <robsond90=yahoo.co.uk@groups.io>:
Hi David,

I'm currently using Wolfblitz shielded cables I bought on Banggood, and I've found them to be very good indeed.  I've been running an ELAD S2, an RSP1A and an HF+ simultaneously without a trace of PC/USB noise on any of them, whereas previously it took a ton of ferrite to get rid of about 90% of it - on supposedly "good quality" cables.  No ferrite is needed on the new cables.

I think they are only made with microUSB or Type-C connectors at the device end, so I had to get a couple of microUSB to Type B adapters for the S2 and RSP1A, but they don't appear to have compromised the end to end shielding.  They aren't expensive when bought direct, and are well worth a look.

Regards,
Dave



From: David Ranch <airspy-groupsio@...>
To: main@airspy.groups.io
Sent: Sunday, 11 March 2018, 16:44
Subject: Re: [airspy] USB cable quality and QRM in a spyserver setup with an Airspy Hf+ and Raspberry PI3. 6 microUSB cable test. #airspyhfplus #bestpractice #raspberrypi


Hello EA5ZL,

Thanks for taking the time to write this up and it's quite illuminating to see how poor some of those cables are.  I too have run into cables that LOOK like their quality made with built-in ferrites on both ends, etc. only to find their crap.  I wish we could find a reliable source of "RF tight" cables that both consistently good and aren't outrageously priced.

Anyway.. I look forward to your results on the OrangePi to see if it's any better.  Btw.. why the OrangePi vs. say a Tinkerboard or a Pine64 or other?  There are SO many SBCs out there now but it's impossible to beat the community and support found with the Raspberry Pi boards.

--David
KI6ZHD







WReeve
 

Niceto - Thanks for looking at this problem. I previously reported USB noise in the spectrum at but received no reply.

I just spent 3 hours in my lab testing various USB cables and ferrite beads. For these tests I terminated the R2 receiver in 50 ohms to eliminate a noise path to the RF input. Most of my tests were with new Volutz USB cables, 1 m and 5 m long, and Fair-Rite clamp-on beads, 31 and 61 mix..

I confirmed what I had suspected before: The USBs and ferrite chokes have only a minor or negligible effect. Instead, the spyserver software or receiver is inconsistent. USB noise can be made to come and go simply by stopping and then starting SDR#.

See attached screenshots. For these, I simply started and stopped the spyserver using SDR# Connect/Disconnect button and Play/Stop button. I did not touch the physical setup in any way. And I could replicate the good and bad spectrum with any cable and any configuration of ferrite beads. In other words.the cable or ferrite chokes had nothing to do with it.

I found that I can almost always make the USB visible or invisible by pressing in order Connect, Play, Connect again (to disconnect) and then Play again, waiting a few seconds between each press. If the noise is there, repeat the sequence and the noise will be gone. Sometimes simply pressing Play, Stop, Play will do it.






--
--
Whitham D. Reeve
Anchorage, Alaska USA
--

smswk
 
Edited

that seems very strange to me.
After testing USB cables (with and without ferrite chokes), Filters and reading application notes
for a couple of months my only solution seems to be a good USB Filter
like the Wuerth EPLE + blocking the USB shield to pcb ground with
a 1M Ohm resistor in parallel with a 4n7 Cap. 

To stop and restart the Software had no effect (and if so it would have surprised me)

vy 73`s de
Stefan

jdow
 

Put some ferrite on every lead that goes out of the Pi. Any one of them can radiate and create problems. Try using a longer cable for the HF+ and placing it further away from the Pi. You are in the near field for at least the HF noise. So doubling distance from the noise source will bring as much as a 9 dB improvement. It will help at much as 6 dB at VHF. A 5 meter cable would not be out of line. But don't go beyond that without careful testing with a powered USB extension.

{^_^}

On 20180311 12:38, ea5ehs@... wrote:
Hello David,
I decided to go de Orange Pi UNO way for different reasons; low cost, Gigabit ethernet outside the usb bus, only one usb 2.0 port.
My theory about the usb qrm from cables is that there is a RPI USB design allowing for this. I have tested one Rpi2B and two Rpi3B with identical results.
QRM is only generated when an active data connection is on, ie when a client connects to spyserver and start sdr#.
When I connect the airspy HF+ to a usb port of my Laptop and rin SDR#, no noise is generated with any of the six tested cables' using the same antennas.
I was considering the Tinkerboard SBC but as I'm runing on solar power, every mW  of power consumption counts. Tinkerboard seems to draw more power than Rpi an Orange pi. Rpi3+airspy accounts for 630mA at 5V during an active connection. I have also taken additional power saving measures like turning off the on Board leds and the HDMI.
Best Ni
EA5ZL

jdow
 

At a guess he means "Blitzwolf" not a name that sounds like the silly CNN announcer. "Blitzwolf USB Cable" turns up a large Panamax boatload and a half of references on Giggle er Google.

{^_^}

On 20180311 13:44, Patrick wrote:
Hi Dave,
Could you please provide the reference of the shielded cable you mention ?
Thanks.
2018-03-11 21:39 GMT+01:00 D R via Groups.Io <robsond90=yahoo.co.uk@groups.io <mailto:robsond90=yahoo.co.uk@groups.io>>:
Hi David,
I'm currently using Wolfblitz shielded cables I bought on Banggood, and I've
found them to be very good indeed.  I've been running an ELAD S2, an RSP1A
and an HF+ simultaneously without a trace of PC/USB noise on any of them,
whereas previously it took a ton of ferrite to get rid of about 90% of it -
on supposedly "good quality" cables.  No ferrite is needed on the new cables.
I think they are only made with microUSB or Type-C connectors at the device
end, so I had to get a couple of microUSB to Type B adapters for the S2 and
RSP1A, but they don't appear to have compromised the end to end shielding. They aren't expensive when bought direct, and are well worth a look.
Regards,
Dave
--------------------------------------------------------------------------------
*From:* David Ranch <airspy-groupsio@...
<mailto:airspy-groupsio@...>>
*To:* main@airspy.groups.io <mailto:main@airspy.groups.io>
*Sent:* Sunday, 11 March 2018, 16:44
*Subject:* Re: [airspy] USB cable quality and QRM in a spyserver setup with
an Airspy Hf+ and Raspberry PI3. 6 microUSB cable test. #airspyhfplus
#bestpractice #raspberrypi
Hello EA5ZL,
Thanks for taking the time to write this up and it's quite illuminating to
see how poor some of those cables are.  I too have run into cables that LOOK
like their quality made with built-in ferrites on both ends, etc. only to
find their crap.  I wish we could find a reliable source of "RF tight"
cables that both consistently good and aren't outrageously priced.
Anyway.. I look forward to your results on the OrangePi to see if it's any
better.  Btw.. why the OrangePi vs. say a Tinkerboard or a Pine64 or other? There are SO many SBCs out there now but it's impossible to beat the
community and support found with the Raspberry Pi boards.
--David
KI6ZHD

Ken Alexander
 

I'd be interested to know if anyone has ever tried one of these.  It's a "USB decrapifier", meant for audio systems.  It isolates computer's USB power from (in our case) the Airspy and replaces it with cleaned-up power from its own linear power supply.  Kind of expensive at US $99 compared to ferrites and better cables.  I've had my eye on them and just wondering.






From: jdow <jdow@...>
To: main@airspy.groups.io
Sent: Monday, March 12, 2018 12:58 AM
Subject: Re: [airspy] USB cable quality and QRM in a spyserver setup with an Airspy Hf+ and Raspberry PI3. 6 microUSB cable test. #airspyhfplus #bestpractice #raspberrypi

Put some ferrite on every lead that goes out of the Pi. Any one of them can
radiate and create problems. Try using a longer cable for the HF+ and placing it
further away from the Pi. You are in the near field for at least the HF noise.
So doubling distance from the noise source will bring as much as a 9 dB
improvement. It will help at much as 6 dB at VHF. A 5 meter cable would not be
out of line. But don't go beyond that without careful testing with a powered USB
extension.

{^_^}

On 20180311 12:38, ea5ehs@... wrote:
> Hello David,
> I decided to go de Orange Pi UNO way for different reasons; low cost, Gigabit
> ethernet outside the usb bus, only one usb 2.0 port.
> My theory about the usb qrm from cables is that there is a RPI USB design
> allowing for this. I have tested one Rpi2B and two Rpi3B with identical results.
> QRM is only generated when an active data connection is on, ie when a client
> connects to spyserver and start sdr#.
> When I connect the airspy HF+ to a usb port of my Laptop and rin SDR#, no noise
> is generated with any of the six tested cables' using the same antennas.
> I was considering the Tinkerboard SBC but as I'm runing on solar power, every mW
>   of power consumption counts. Tinkerboard seems to draw more power than Rpi an
> Orange pi. Rpi3+airspy accounts for 630mA at 5V during an active connection. I
> have also taken additional power saving measures like turning off the on Board
> leds and the HDMI.
>
> Best Ni
> EA5ZL
>
>





Siegfried Jackstien
 

hmmm ... their dac and adc could make a nice sdr backend with high quality

dg9bfc sigi


Am 12.03.2018 um 13:45 schrieb Ken Alexander:

I'd be interested to know if anyone has ever tried one of these.  It's a "USB decrapifier", meant for audio systems.  It isolates computer's USB power from (in our case) the Airspy and replaces it with cleaned-up power from its own linear power supply.  Kind of expensive at US $99 compared to ferrites and better cables.  I've had my eye on them and just wondering.






From: jdow <jdow@...>
To: main@airspy.groups.io
Sent: Monday, March 12, 2018 12:58 AM
Subject: Re: [airspy] USB cable quality and QRM in a spyserver setup with an Airspy Hf+ and Raspberry PI3. 6 microUSB cable test. #airspyhfplus #bestpractice #raspberrypi

Put some ferrite on every lead that goes out of the Pi. Any one of them can
radiate and create problems. Try using a longer cable for the HF+ and placing it
further away from the Pi. You are in the near field for at least the HF noise.
So doubling distance from the noise source will bring as much as a 9 dB
improvement. It will help at much as 6 dB at VHF. A 5 meter cable would not be
out of line. But don't go beyond that without careful testing with a powered USB
extension.

{^_^}

On 20180311 12:38, ea5ehs@... wrote:
> Hello David,
> I decided to go de Orange Pi UNO way for different reasons; low cost, Gigabit
> ethernet outside the usb bus, only one usb 2.0 port.
> My theory about the usb qrm from cables is that there is a RPI USB design
> allowing for this. I have tested one Rpi2B and two Rpi3B with identical results.
> QRM is only generated when an active data connection is on, ie when a client
> connects to spyserver and start sdr#.
> When I connect the airspy HF+ to a usb port of my Laptop and rin SDR#, no noise
> is generated with any of the six tested cables' using the same antennas.
> I was considering the Tinkerboard SBC but as I'm runing on solar power, every mW
>   of power consumption counts. Tinkerboard seems to draw more power than Rpi an
> Orange pi. Rpi3+airspy accounts for 630mA at 5V during an active connection. I
> have also taken additional power saving measures like turning off the on Board
> leds and the HDMI.
>
> Best Ni
> EA5ZL
>
>






Stepan Synek
 

Hello Witham,
I have similar observation with my other brand SDR. (Elad FDM-S1, SDRPlay rsp 2) 
I have two monitors connected to my Lenovo notebook. Sometimes the picture displayed on the second screen affects the reception noise “spikes”) on the SDR. I had thought that LCD monitor creates some RFI, but switching off this monitor did not help.
It also differ depends on antenna type and frequency... One day I have “spikes” the other day they are gone with the same setup. (????)
Maybe to add bunch of the ferrite clamps to the monitor cable could help, but I haven’t found time to verify it yet.
Please continue with your lab tests :-)
regards
Stepan 

Dana Myers
 

Thank you very much for sharing this research. I noted a substantial improvement in RFI when I replaced my no-name cable with a Volutz cable. Just brilliant information.

Thanks and 73,
Dana  K6JQ

Pete Smith <n4zr@...>
 

Can you elaborate, Dana.  What were the characteristics of the noise that was helped by changing out the cable?  I ask because my shack is full of USB cables and I have suspicions about their contribution to my noise floor.

73, Pete N4ZR
Check out the Reverse Beacon Network 
at <http://reversebeacon.net>, now 
spotting RTTY activity worldwide. 
For spots, please use your favorite 
"retail" DX cluster.
On 3/13/2018 5:57 PM, Dana Myers wrote:

Thank you very much for sharing this research. I noted a substantial improvement in RFI when I replaced my no-name cable with a Volutz cable. Just brilliant information.

Thanks and 73,
Dana  K6JQ

Dana Myers
 

On 3/13/2018 6:42 PM, Pete Smith wrote:

Can you elaborate, Dana.  What were the characteristics of the noise that was helped by changing out the cable?  I ask because my shack is full of USB cables and I have suspicions about their contribution to my noise floor.


It came in various forms.

More innocuous noise was seen as repetitive spikes in the waterfall.
It made me think I had a monitor or TV leaking into my actual receiving
antenna and it was pretty much everywhere on HF.

For a 2-pack of 10' cables, $17 on eBay was a deal.

73,
Dana  K6JQ




Ian DXer
 
Edited

Hi Dana,

Pleasing to read your report on your success with the Volutz USB cables.

I was looking at the Volutz Facebook page & I note that Volutz have just released a new Apple Lighting Cable.
For noise immunity I like the metal shroud that links the foil shield of the cable & surrounds the connector & components
underneath. One also gets a better look at the dual cable shielding from the drawing on the Facebook page.
Are these SMD components part of the lightning spec or are they part of Volutz's attention to EMI/EMC or impedance
matching?

I see a similar shroud on their USB C cable from their Facebook page.
What's not clear to me is if Volutz use a metal shroud on their connectors for their USB 2.0 to micro USB cables or
any filtering SMD components (if that's what they are?) similar to their new Apple Lightning Cable.
The Volutz website is scant with close up pics & tech data.

A further improvement to their USB 2.0 to micro usb cables would be to have a foil shield between the data & power pairs.

I purchased a replacement USB cable (CableCreation/Xillie) from the Internet last week. It arrived on Monday. It is supposedly triple shielded, but I suspect these are 'just
words' from a Chinese supplier via Amazon. I compared the the noise performance between AIRSPYHF+ supplied USB cable with my own
added mix of ferrites attached, also a Samsung USB cable, the CableCreation USB & the CableCreation Lead with a mix of ferrites.
Test freqs were roughly every 1MHz between 2 & 30MHz. Conclusions: I didn't gain the results I expected from the CableCreation USB cable, results were
similar to the plain Samsung Cable. But what brought best results was having ferrites on either the existing AirSpyHF+ USB cable or the CableCreation USB cable (similar results).
That said, for my own electro smog environment results were typically only a 2dB improvement to noise floor for the USB cables with the ferrites attached. 
But on the better end of the results scale 'on some' frequencies I noted a 6-10dB improvement (with ferrites).
I'm sure if I purchased a better screened USB cable (similar to the standard of my router CAT6 S/FTP patch cables) I should hopefully see better results.

Every dxer has a unique RFI environment with their own unique challenges, some requiring a huge investment of time & effort (mine's only in the early stages). 
Our new Samsung refrigerator is the latest to be added to the RFI hit list (I'll try to mute my grumble).

73

Ian

jdow
 

Screening is good. Breaking ground loops, AF or RF, is a good thing, too. Ferrite makes the ground loops lossy as it breaks them. This is sort of the best of both worlds. And there is something to be said for keeping RF that is outside of cables where it belongs, on the outside of the box. So making a good electrical bond from each of the box's connectors to the box itself may provide you with a quite worthwhile improvement in behavior. It should not make it any worse. (And done carefully it will not change the cosmetics of the box. Braided shield from small diameter coax is a nice tool for this. Clean the inside of the holes and the inside of the box for the 10 MHz ref (AirSpy only) and USB connector holes. Then when installing the cover mush some of the braid between the edges of the hole and the connector shield. For the RF clean off a space just to about half way to the outside of the lockwasher. Then when tightening it you will get a nice ground to the coax shields for the RF input connector(s).

Also, unless you are running a very low efficiency antenna at HF, test for the interference when the band is open. If you cannot see it then it doesn't matter even if you can see it with a 50 ohm dummy load and with a small test signal present.

{^_^}

On 20180313 21:32, Ian DXer wrote:
Hi Dana,
Pleasing to read your report on your success with the Volutz USB cables.
I was looking at the Volutz Facebook page & I note that Volutz have just released a new Apple Lighting Cable.
For noise immunity I like the metal shroud that links the foil shield of the cable & surrounds the connector & components
underneath. One also gets a better look at the dual cable shielding from the drawing on the Facebook page.
Are these SMD components part of the lightning spec or are they part of Volutz's attention to EMI/EMC or impedance
matching?
I see a similar shroud on their USB C cable from their Facebook page.
What's not clear to me is if Volutz use a metal shroud on their connectors for their USB 2.0 to micro USB cables or
any filtering SMD components (if that's what they are?) similar to their new Apple Lightning Cable.
The Volutz website is scant with close up pics & tech data.
A further improvement to their USB 2.0 to micro usb cables would be to have a foil shield between the data & power pairs.
I purchased a replacement USB cable (CableCreation/Xillie) from the Internet last week. It arrived on Monday. It is supposedly triple shielded, but I suspect these are 'just
words' from a Chinese supplier via Amazon. I compared the the noise performance between AIRSPYHF+ supplied USB cable with my own
added mix of ferrites attached, also a Samsung USB cable, the CableCreation USB & the CableCreation Lead with a mix of ferrites.
Test freqs were roughly every 1MHz between 2 & 30MHz. Conclusions: I didn't gain the results I expected from the CableCreation USB cable, results were
similar to the plain Samsung Cable. But what brought best results was having ferrites on either the existing AirSpyHF+ USB cable or the CableCreation USB cable (similar results).
That said, for my own electro smog environment results were typically only a 2dB improvement to noise floor for the USB cables with the ferrites attached.
But on the better end of the results scale 'on some' frequencies I noted a 6-10dB improvement (with ferrites).
I'm sure if I purchased a better screened USB cable (similar to the standard of my router CAT6 S/FTP patch cables) I should hopefully see better results.
Every dxer has a unique RFI environment with their own unique challenges, some requiring a huge investiture of time & effort (mine's only in the early stages).
Our new Samsung refrigerator is the latest to be added to the RFI hit list (I'll try to mute my grumble).
73
Ian

David Ranch
 


For a 2-pack of 10' cables [Volutz], $17 on eBay was a deal.


Wow.. 10'?  I'd assume there is some pretty serious voltage drop over that!  Regardless, I'll have to give them a look.  Thanks.

--David
KI6ZHD