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Author Topic: Using bluetooth keyboards and mice in the stack  (Read 230 times)

AE8GS

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Using bluetooth keyboards and mice in the stack
« on: December 08, 2022, 02:22:20 PM »

I have issues with RF affecting my computer on my radio desk. Sometimes after transmitting my mouse stops working, and I have to unplug and then re-plug it in. There have been other issues with my PC but less frequent.

I am working on station grounding and have some ferrites on order to see what I can do.  I am fairly close to my antennas, as they are vertical wires along my house, working against buried radials. This proximity might make matters worse as I might have "good" RF coming into the shack off the antenna.

Anyhow, I was wondering if using bluetooth for keyboard and mouse might simply eliminate some of my problems. I don't really care for bluetooth for keyboard/mouse but would be willing to use it in this case.

Any thoughts on how effective this would be, and does using bluetooth like this create any new problems?
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G8FXC

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Re: Using bluetooth keyboards and mice in the stack
« Reply #1 on: December 08, 2022, 02:34:30 PM »

I do find that Bluetooth is more resilient than wired USB. It's running at microwave frequencies, so the interaction with HF radio is minimal and there are no long cables to act as receiving antennae.

Martin G8FXC
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W9IQ

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Re: Using bluetooth keyboards and mice in the stack
« Reply #2 on: December 08, 2022, 02:40:33 PM »

What type of antenna, how close to the shack and have you installed any common mode chokes?

- Glenn W9IQ
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- Glenn W9IQ

God runs electromagnetics on Monday, Wednesday and Friday by the wave theory and the devil runs it on Tuesday, Thursday and Saturday by the Quantum theory.

AE8GS

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Re: Using bluetooth keyboards and mice in the stack
« Reply #3 on: December 08, 2022, 03:45:44 PM »

What type of antenna, how close to the shack and have you installed any common mode chokes?

- Glenn W9IQ

I have a fan vertical (three wires for 10/15/20) with ground radials, and they are probably 15 feet from my desk, separated by an outside wall with a lot of windows. Coax enters the house, goes through a coax switch and then my radio.

I ordered a bunch of Fair-Rite snap-on chokes of various sizes and will receive them soon. Wrt coax, I was going to start with one or two near the antenna, and some in the shack near the antenna switch and/or the radio.

I expected to use some chokes on the mouse and keyboard cords, but then thought maybe I could just eliminate those cords with Bluetooth.

There are also power and USB cables to worry about.

I have been reading a lot, including the papers by W1HIS and W9JI.

I saw an article on a home-brew common mode current detector, and thought that would be really useful. But such things don't seem to be very common in my experience - maybe they don't work that well in practice.

As a new ham, I am just getting started on this issue.
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W6MK

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Re: Using bluetooth keyboards and mice in the stack
« Reply #4 on: December 08, 2022, 08:37:01 PM »

As a new ham, I am just getting started on this issue.

If you must begin with snap-on ferrites of whatever mixture, wrap your coax through them several times if possible. Otherwise, look to putting properly-designed, carefully-placed common mode chokes on your antenna feed lines.

Proximity of your antenna ultimately may be a major challenge.
« Last Edit: December 08, 2022, 08:40:00 PM by W6MK »
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N2TO

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Re: Using bluetooth keyboards and mice in the stack
« Reply #5 on: December 08, 2022, 09:16:16 PM »

I had major RF problems with a Microsoft Bluetooth keyboard. I returned it and bought a Logitech K380 which works really well. I thought the round keys would be weird but they're a non-issue. The keyboard is nicely angled and I love it. I also have a Logitech Bluetooth mouse, cannot remember the model. Also works super-duper.

I also use Fair-Rite Mix 43 bought snap-ons bought from Arrow on power and SignaLink USB interface cables.

GL

73 Kevin N2TO
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G4AON

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Re: Using bluetooth keyboards and mice in the stack
« Reply #6 on: December 09, 2022, 03:13:38 AM »

Any cables to your computer can pick up RF and cause the mouse to freeze, it's not always the mouse cable. I have had the same "mouse freezing" with a Logitech wireless mouse.

While there is nothing wrong with randomly adding grounding wires, ferrite rings, etc. The much better solution is to measure the level of RF on the cables, rather than guess, then add a ferrite ring and measure again.

I had RF pickup on a spare coax that is occasionally used with a vertical, it is laid on the ground and connects to one of the switched antenna sockets on my Palstar ATU. On 80m and 40m there was a lot of RF coming into the shack via that cable. A common mode choke comprising a few turns of coax through an FT240-31 ferrite ring completely removed the RF. Ideally use PTFE coax for common mode chokes, but RG58 will suffice for low power use.

MFJ have an RF clamp on current meter, item number MFJ-854, at $159.95. Or you can make your own, see:
http://www.ifwtech.co.uk/g3sek/clamp-on/clamp-on.htm

The above home brew meter works well enough, mine is +/-20% from 1.8 to 70 MHz and was made using parts from the junk box.

73 Dave
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G8FXC

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Re: Using bluetooth keyboards and mice in the stack
« Reply #7 on: December 09, 2022, 03:55:12 AM »

What type of antenna, how close to the shack and have you installed any common mode chokes?

- Glenn W9IQ

...

I ordered a bunch of Fair-Rite snap-on chokes of various sizes and will receive them soon. Wrt coax, I was going to start with one or two near the antenna, and some in the shack near the antenna switch and/or the radio.

...

Snap-on ferrites are of very limited value for HF applications - they just don't add enough impedance to do anything useful. Buy several rings - something like this https://www.rsgbshop.org/acatalog/Ferrite-Ring-654.html#SID=41 and wind multiple turns of the cable through it. To make any significant difference to RFI in the shack, you really need eight or ten turns of cable through the ring. To get the same effect with snap-ons, you need a large number of them. MFJ make a couple of common mode chokes with beads - and they put thirty or more on the cable - see this video https://youtu.be/XMixWqYHbWE?t=145 for the internal details of one of them that has been burned out...

Martin (G8FXC)
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W9IQ

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Re: Using bluetooth keyboards and mice in the stack
« Reply #8 on: December 09, 2022, 04:29:46 AM »

The antenna is quite close to your shack. It is sometimes helpful to reduce your transmit power to find the power level at which the interference is gone. This will give you some idea about the magnitude of remediation you are facing.

Regarding ferrite for suppression applications, the mix or type of ferrite makes a significant difference in effectiveness. For HF applications, type 31 is your best choice with type 43 coming in as a close second. Avoid any other types. Be warey of eBay, etc. vendors selling ferrite if you want the real deal.

Ground plane antennas can couple significant RF energy onto the exterior of the coax shield. This then follows the coax into the shack. You should have your coax shield tied to your power mains ground just before it enters the shack in any case. In addition, a common mode choke or two on the coax is advised. You can easily make your own common mode chokes. Let me know if you would like me to post the information for you.

Using snap-on type 31 or 43 ferrite on all of your computer cables may also help. Where possible, place a few turns of the cable around the core before snapping it closed. This greatly magnifies the choking effect (it increases as the number of turns squared).

- Glenn W9IQ
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- Glenn W9IQ

God runs electromagnetics on Monday, Wednesday and Friday by the wave theory and the devil runs it on Tuesday, Thursday and Saturday by the Quantum theory.

N2TO

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Re: Using bluetooth keyboards and mice in the stack
« Reply #9 on: December 09, 2022, 04:34:59 AM »

Prices like everything for Fair-Rite toroids from Arrow and other authorized resellers had gone through the roof. In 2006 I bought a bunch and I have them in series on my cables. I didn't rely on just one. Have three on each. Multiple turns for sure. I did best to keep turns parallel to each other as well.

Octopart helps show prices of auth resellers. I also bought from Arrow when they had free shipping which was huge.   https://octopart.com/

GL

73 Kevin N2TO
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W9IQ

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Re: Using bluetooth keyboards and mice in the stack
« Reply #10 on: December 09, 2022, 04:40:40 AM »

Lately, I have found the best Fair-Rite prices at Newark. The are currently out of stock on FT240-31 however.

- Glenn W9IQ
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- Glenn W9IQ

God runs electromagnetics on Monday, Wednesday and Friday by the wave theory and the devil runs it on Tuesday, Thursday and Saturday by the Quantum theory.

N2TO

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Re: Using bluetooth keyboards and mice in the stack
« Reply #11 on: December 09, 2022, 06:16:04 AM »

Typo, make that 2016. I just checked my order and what I bought for 1.20 each is now over 3.60 each, cheapest price. Same gist with larger cores. Maybe it's time I buy some more before they go up more. Like chasing the market on a stock.

73 Kevin N2TO
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AE8GS

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Re: Using bluetooth keyboards and mice in the stack
« Reply #12 on: December 11, 2022, 08:36:16 PM »



<snip>

MFJ have an RF clamp on current meter, item number MFJ-854, at $159.95. Or you can make your own, see:
http://www.ifwtech.co.uk/g3sek/clamp-on/clamp-on.htm

The above home brew meter works well enough, mine is +/-20% from 1.8 to 70 MHz and was made using parts from the junk box.

73 Dave


Thanks for the references. I believe I saw the same home-brew instructions somewhere, and would like to build one.

It seems like being able to measure the common mode current is the key to a systematic approach.
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AE8GS

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Re: Using bluetooth keyboards and mice in the stack
« Reply #13 on: December 11, 2022, 09:01:09 PM »

Thanks everyone for all of the advice.

As follow-up, my order of Fair-Rite snap-on chokes arrived. They are all Type 31, and I got IDs of 0.5", 0.4", and 0.25". I started with just a few to see how much they would help:

  • Snap-on choke on coax as it enters the house (looping not possible)
  • Mouse and keyboard cords near the computer - each with a snap-on choke with 3 loops
  • My USB cable for CAT had one built-in choke, and I added a snap-on choke at the other end near the computer with 2 loops.

Surprisingly, this seemed to improve things enough to the point that I have not (yet) seen any computer issues! I was running at full power (100W) for quite a bit on the recent 10M contest.

I don't know how much margin I have, but I have plenty more chokes! At a minimum, I will add a couple more on the coax, especially one at the antenna base outside. I will stay with corded mice and keyboards for a while, to see how it goes.

I agree with W9IQ that Newark seems to have the best prices for Fair-Rite. One thing that surprised me is that these were no more expensive (maybe cheaper) than the DX Engineering ones that are branded as DX Engineering. While I think the DX Engineering ones are probably fine, the Fair-Rite ones are a well-known product with more detailed performance data documentation.


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