Can anyone recommend me a KM or KVM switch with USB on board please?

I have recently changed from a M$ Desktop (wireless mouse and keyboard)
to a Cherry Gentix equivalent and have just discovered that the USB
Bluetooth receiver plugged into my existing KVM switch is generating a
low level buzz on the audio feed to my speakers. This never happened
with the M$ kit but the keyboard was becoming intermittent so I had no
option - the M$ Desktop that I had is no longer made it seems.)
After much pratting about I have discovered that if the BT Rx is plugged
directly into my main PC there is no buzz and audio is reproduced
perfectly. However if I plug the BT Rx into the KVM switch I get the buzz.
I have two desktop PCs, one that is rarely used running XPSP3, and my
normal PC running W10Pro. As my (latest) monitor has two inputs (HDMI
and DisplayPort) I no longer need the video switching capability but it
is useful to have soft control of the keyboard and mouse should I need
to use the XP machine.
I have tried a longish USB extension cable on the BT Rx with three turns
passed through a ferrite bead but it makes no difference, the buzz is
still present.
I have tried everything in terms of hum loops etc but this is not a 50Hz
or 100Hz hum, more a buzz which sounds like USB clock getting onto the
supply wires in the cables. Using the soft switch to change over to the
XP3 machine (switched off but connected to main) kills the buzz.

If anyone has polite suggestions of a cure, or a reasonably priced KM or
KVM HDMI switch I would be most obliged.

On Thu, 11 Jan 2024 14:51:16 +0000, Woody wrote:

> If anyone has polite suggestions of a cure, or a reasonably priced KM or
> KVM HDMI switch I would be most obliged.

I am very impressed with all of the ATEN KVMUA switches I have had, four
different models in various places. I currently have (and am using right
now) a two port one that does KVM plus USB and audio. No problems, but it
is all wired.

On 11/01/2024 in message <unov97$31bjo$1@dont-email.me> Woody wrote:

>
>Can anyone recommend me a KM or KVM switch with USB on board please?
>
>I have recently changed from a M$ Desktop (wireless mouse and keyboard) to
>a Cherry Gentix equivalent and have just discovered that the USB Bluetooth
>receiver plugged into my existing KVM switch is generating a low level
>buzz on the audio feed to my speakers. This never happened with the M$ kit
>but the keyboard was becoming intermittent so I had no option - the M$
>Desktop that I had is no longer made it seems.)
>After much pratting about I have discovered that if the BT Rx is plugged
>directly into my main PC there is no buzz and audio is reproduced
>perfectly. However if I plug the BT Rx into the KVM switch I get the buzz.
>I have two desktop PCs, one that is rarely used running XPSP3, and my
>normal PC running W10Pro. As my (latest) monitor has two inputs (HDMI and
>DisplayPort) I no longer need the video switching capability but it is
>useful to have soft control of the keyboard and mouse should I need to use
>the XP machine.
>I have tried a longish USB extension cable on the BT Rx with three turns
>passed through a ferrite bead but it makes no difference, the buzz is
>still present.
>I have tried everything in terms of hum loops etc but this is not a 50Hz
>or 100Hz hum, more a buzz which sounds like USB clock getting onto the
>supply wires in the cables. Using the soft switch to change over to the
>XP3 machine (switched off but connected to main) kills the buzz.
>
>If anyone has polite suggestions of a cure, or a reasonably priced KM or
>KVM HDMI switch I would be most obliged.

I am using this one:

https://www.amazon.co.uk/gp/product/B07L6VSFC8/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

Switches keyboard and mouse (not graphics) and I like it because I don't
have to keep pressing one button to cycle through, I can go straight to
the machine I want. Haven't use it with sound really, my PC just beeps at
me!

--
Jeff Gaines Dorset UK
All those who believe in psychokinesis raise my hand.

On Thu 11/01/2024 15:05, Bob Eager wrote:
> On Thu, 11 Jan 2024 14:51:16 +0000, Woody wrote:
>
>> If anyone has polite suggestions of a cure, or a reasonably priced KM or
>> KVM HDMI switch I would be most obliged.
>
> I am very impressed with all of the ATEN KVMUA switches I have had, four
> different models in various places. I currently have (and am using right
> now) a two port one that does KVM plus USB and audio. No problems, but it
> is all wired.

Thanks for that Bob but unfortunately £80++ is a bit more than I wanted
to pay - albeit the CS22H will do exactly what I want!!

Woody wrote:

> Can anyone recommend me a KM or KVM switch with USB on board please?

Generally ones from Aten, I used to have a 4xDVI+PS/2+audio, now I have
a 2xDP+USB+audio. They don't guarantee it, but it does work with a
Logitech mouse receiver.

As a company they produce firmware fixes of their products for many years.

On 11/01/2024 14:51, Woody wrote:
>
> Can anyone recommend me a KM or KVM switch with USB on board please?
>
> I have recently changed from a M$ Desktop (wireless mouse and keyboard)
> to a Cherry Gentix equivalent and have just discovered that the USB
> Bluetooth receiver plugged into my existing KVM switch is generating a
> low level buzz on the audio feed to my speakers. This never happened
> with the M$ kit but the keyboard was becoming intermittent so I had no
> option - the M$ Desktop that I had is no longer made it seems.)
> After much pratting about I have discovered that if the BT Rx is plugged
> directly into my main PC there is no buzz and audio is reproduced
> perfectly. However if I plug the BT Rx into the KVM switch I get the buzz.
> I have two desktop PCs, one that is rarely used running XPSP3, and my
> normal PC running W10Pro. As my (latest) monitor has two inputs (HDMI
> and DisplayPort) I no longer need the video switching capability but it
> is useful to have soft control of the keyboard and mouse should I need
> to use the XP machine.
> I have tried a longish USB extension cable on the BT Rx with three turns
> passed through a ferrite bead but it makes no difference, the buzz is
> still present.
> I have tried everything in terms of hum loops etc but this is not a 50Hz
> or 100Hz hum, more a buzz which sounds like USB clock getting onto the
> supply wires in the cables. Using the soft switch to change over to the
> XP3 machine (switched off but connected to main) kills the buzz.
>
> If anyone has polite suggestions of a cure, or a reasonably priced KM or
> KVM HDMI switch I would be most obliged.

If you can find an alternative PSU of the same rating and polarity for
the KVM, try swapping that in to see if that fixes the hash.

I use two KVMs, one in normal use, the other as a backup ...

The one currently in normal use is a Belkin OmniView PRO3 16-Port KVM
Switch, USB/PS2 + VGA, which I bought second-hand/used for £25 inc p&p,
a lucky find on eBay.

Previously I paid £40 + surcharge of £7 p&p* for 2 x Belkin OmniView
PRO2 + 1 x Belkin OmniView PRO3, all 4-port, + an assortment of cables.
One of the PRO2 was an older model, PS2 only, and was faulty (magenta
output, so green channel broken), the other I used to have daisy-chained
to the PRO3 for my old tower W2k machines, but it became redundant when
my monitor caught fire (literally, black smoke rising out of the back of
it, I used welding gloves to carry it outside at arms' length). The
PRO3 worked for many years after but died in a thunderstorm last summer.

The backup system is a 4-port USB-powered one with analog video, for
around £10 excluding cables from eBay, but I can't find the original
sale item now.

Previous to all the above, I had a Belkin SOHo 4-Port model number now
forgotten.

All of the above have been in use with a Logitech MK520 wireless
keyboard & mouse set, the keyboard model number seems to be K540, the
mouse model number M310. I still have an Amazon link, but it's no
longer available, presumably because it is a superseded model:
https://www.amazon.co.uk/dp/B003ZWL9G4/ref=pe_217191_31005151_3p_M3_dp_1

None of the above combinations have caused me any interference on sound,
and I play a lot of music through a Terratec USB sound-card on the end
of a long USB lead to take it to the stereo the other side of this room.

* Something to which I wouldn't normally agree - I'm on the mainland,
no ferries involved, so no more remote than some areas of Wales or
Galloway in southern Scotland, which AFAIK don't incur extra charges for
delivering there.

--

Fake news kills!

I may be contacted via the contact address given on my website:
www.macfh.co.uk

Woody <harrogate3@ntlworld.com> wrote:
>
> Can anyone recommend me a KM or KVM switch with USB on board please?

I have an AIMOS 8 port HDMI+USB KVM switch from Amazon. No longer listed,
but they have 4 port versions. The PiKVM folks also have a list of
recommended switches, mostly ezCoo brand, where they list their limitations:

https://docs.pikvm.org/multiport/#list-of-tested-kvms

> I have tried everything in terms of hum loops etc but this is not a 50Hz
> or 100Hz hum, more a buzz which sounds like USB clock getting onto the
> supply wires in the cables. Using the soft switch to change over to the
> XP3 machine (switched off but connected to main) kills the buzz.

Couldn't comment about any effects on audio, never used external speakers.

Theo

On Thu 11/01/2024 17:05, Java Jive wrote:
> On 11/01/2024 14:51, Woody wrote:
>>
>> Can anyone recommend me a KM or KVM switch with USB on board please?
>>
>> I have recently changed from a M$ Desktop (wireless mouse and
>> keyboard) to a Cherry Gentix equivalent and have just discovered that
>> the USB Bluetooth receiver plugged into my existing KVM switch is
>> generating a low level buzz on the audio feed to my speakers. This
>> never happened with the M$ kit but the keyboard was becoming
>> intermittent so I had no option - the M$ Desktop that I had is no
>> longer made it seems.)
>> After much pratting about I have discovered that if the BT Rx is
>> plugged directly into my main PC there is no buzz and audio is
>> reproduced perfectly. However if I plug the BT Rx into the KVM switch
>> I get the buzz.
>> I have two desktop PCs, one that is rarely used running XPSP3, and my
>> normal PC running W10Pro. As my (latest) monitor has two inputs (HDMI
>> and DisplayPort) I no longer need the video switching capability but
>> it is useful to have soft control of the keyboard and mouse should I
>> need to use the XP machine.
>> I have tried a longish USB extension cable on the BT Rx with three
>> turns passed through a ferrite bead but it makes no difference, the
>> buzz is still present.
>> I have tried everything in terms of hum loops etc but this is not a
>> 50Hz or 100Hz hum, more a buzz which sounds like USB clock getting
>> onto the supply wires in the cables. Using the soft switch to change
>> over to the XP3 machine (switched off but connected to main) kills the
>> buzz.
>>
>> If anyone has polite suggestions of a cure, or a reasonably priced KM
>> or KVM HDMI switch I would be most obliged.
>
> If you can find an alternative PSU of the same rating and polarity for
> the KVM, try swapping that in to see if that fixes the hash.
>
> I use two KVMs, one in normal use, the other as a backup ...
>
> The one currently in normal use is a Belkin OmniView PRO3 16-Port KVM
> Switch, USB/PS2 + VGA, which I bought second-hand/used for £25 inc p&p,
> a lucky find on eBay.
>
> Previously I paid £40 + surcharge of £7 p&p* for 2 x Belkin OmniView
> PRO2 + 1 x Belkin OmniView PRO3, all 4-port, + an assortment of cables.
> One of the PRO2 was an older model, PS2 only, and was faulty (magenta
> output, so green channel broken), the other I used to have daisy-chained
> to the PRO3 for my old tower W2k machines, but it became redundant when
> my monitor caught fire (literally, black smoke rising out of the back of
> it, I used welding gloves to carry it outside at arms' length).  The
> PRO3 worked for many years after but died in a thunderstorm last summer.
>
> The backup system is a 4-port USB-powered one with analog video, for
> around £10 excluding cables from eBay, but I can't find the original
> sale item now.
>
> Previous to all the above, I had a Belkin SOHo 4-Port model number now
> forgotten.
>
> All of the above have been in use with a Logitech MK520 wireless
> keyboard & mouse set, the keyboard model number seems to be K540, the
> mouse model number M310.  I still have an Amazon link, but it's no
> longer available, presumably because it is a superseded model:
> https://www.amazon.co.uk/dp/B003ZWL9G4/ref=pe_217191_31005151_3p_M3_dp_1
>
> None of the above combinations have caused me any interference on sound,
> and I play a lot of music through a Terratec USB sound-card on the end
> of a long USB lead to take it to the stereo the other side of this room.
>
>
> *  Something to which I wouldn't normally agree  -  I'm on the mainland,
> no ferries involved, so no more remote than some areas of Wales or
> Galloway in southern Scotland, which AFAIK don't incur extra charges for
> delivering there.
>

Thanks for your comments Charles.
The KVM switch that I have is powered from the PCs through USB, there is
no separate power supply. If I switch to the XP PC when it is unpowered
but still connected to the mains lead the buzz disappears. If I unplug
the audio input or output of the switch whilst selected on the W10
machine the buzz disappears. Most significantly if I unplug the BT
receiver (mini USB) the buzz also disappears.
Ergo I conclude that the receiver is radiating interference onto the USB
connection to the W10 PC. I thought it could be a radiation issue so
fitted an extension USB cable and wound three turns of it into a
substantial ferrite tube but it made no difference.
My previous M$ Desktop 2000 was connected in exactly the same
configuration and was never a problem.
Methinks an email to Cherry might be appropriate?

On 11/01/2024 20:23, Woody wrote:
> On Thu 11/01/2024 17:05, Java Jive wrote:
>> On 11/01/2024 14:51, Woody wrote:
>>>
>>> Can anyone recommend me a KM or KVM switch with USB on board please?
>>>
>>> I have recently changed from a M$ Desktop (wireless mouse and
>>> keyboard) to a Cherry Gentix equivalent and have just discovered that
>>> the USB Bluetooth receiver plugged into my existing KVM switch is
>>> generating a low level buzz on the audio feed to my speakers. This
>>> never happened with the M$ kit but the keyboard was becoming
>>> intermittent so I had no option - the M$ Desktop that I had is no
>>> longer made it seems.)
>>> After much pratting about I have discovered that if the BT Rx is
>>> plugged directly into my main PC there is no buzz and audio is
>>> reproduced perfectly. However if I plug the BT Rx into the KVM switch
>>> I get the buzz.
>>> I have two desktop PCs, one that is rarely used running XPSP3, and my
>>> normal PC running W10Pro. As my (latest) monitor has two inputs (HDMI
>>> and DisplayPort) I no longer need the video switching capability but
>>> it is useful to have soft control of the keyboard and mouse should I
>>> need to use the XP machine.
>>> I have tried a longish USB extension cable on the BT Rx with three
>>> turns passed through a ferrite bead but it makes no difference, the
>>> buzz is still present.
>>> I have tried everything in terms of hum loops etc but this is not a
>>> 50Hz or 100Hz hum, more a buzz which sounds like USB clock getting
>>> onto the supply wires in the cables. Using the soft switch to change
>>> over to the XP3 machine (switched off but connected to main) kills
>>> the buzz.
>>>
>>> If anyone has polite suggestions of a cure, or a reasonably priced KM
>>> or KVM HDMI switch I would be most obliged.
>>
>> If you can find an alternative PSU of the same rating and polarity for
>> the KVM, try swapping that in to see if that fixes the hash.
>>
>> I use two KVMs, one in normal use, the other as a backup ...
>>
>> The one currently in normal use is a Belkin OmniView PRO3 16-Port KVM
>> Switch, USB/PS2 + VGA, which I bought second-hand/used for £25 inc
>> p&p, a lucky find on eBay.
>>
>> Previously I paid £40 + surcharge of £7 p&p* for 2 x Belkin OmniView
>> PRO2 + 1 x Belkin OmniView PRO3, all 4-port, + an assortment of
>> cables. One of the PRO2 was an older model, PS2 only, and was faulty
>> (magenta output, so green channel broken), the other I used to have
>> daisy-chained to the PRO3 for my old tower W2k machines, but it became
>> redundant when my monitor caught fire (literally, black smoke rising
>> out of the back of it, I used welding gloves to carry it outside at
>> arms' length).  The PRO3 worked for many years after but died in a
>> thunderstorm last summer.
>>
>> The backup system is a 4-port USB-powered one with analog video, for
>> around £10 excluding cables from eBay, but I can't find the original
>> sale item now.
>>
>> Previous to all the above, I had a Belkin SOHo 4-Port model number now
>> forgotten.
>>
>> All of the above have been in use with a Logitech MK520 wireless
>> keyboard & mouse set, the keyboard model number seems to be K540, the
>> mouse model number M310.  I still have an Amazon link, but it's no
>> longer available, presumably because it is a superseded model:
>> https://www.amazon.co.uk/dp/B003ZWL9G4/ref=pe_217191_31005151_3p_M3_dp_1
>>
>> None of the above combinations have caused me any interference on
>> sound, and I play a lot of music through a Terratec USB sound-card on
>> the end of a long USB lead to take it to the stereo the other side of
>> this room.
>>
>>
>> *  Something to which I wouldn't normally agree  -  I'm on the
>> mainland, no ferries involved, so no more remote than some areas of
>> Wales or Galloway in southern Scotland, which AFAIK don't incur extra
>> charges for delivering there.

Rereading your OP and restated comments below, I missed that, I think,
you're also switching analog audio output from the PCs via the KVM? Pls
confirm, as otherwise I'm way off mark. The PRO models I described
above don't have the connections to allow that, and, although the SOHo
model did, I never actually did this except once to see if it actually
worked, which of course it did. However, I've never wanted to do this
on a permanent basis, because if I have media playing on one PC, I
wouldn't want the sound to be interrupted while working on another.
However, as always, your own needs are allowed to differ from mine!

> The KVM switch that I have is powered from the PCs through USB, there is
> no separate power supply. If I switch to the XP PC when it is unpowered
> but still connected to the mains lead the buzz disappears.

If my assumption above is correct, that is presumably because the XP
machine, being switched off, is not acting as an audio source into the KVM.

> If I unplug
> the audio input or output of the switch whilst selected on the W10
> machine the buzz disappears.

Again because, like the XP machine being switched off, there is no audio
coming into the KVM.

> Most significantly if I unplug the BT
> receiver (mini USB) the buzz also disappears.
> Ergo I conclude that the receiver is radiating interference onto the USB
> connection to the W10 PC.

No, I don't think so, surely it's much more likely that hash is leaking
directly onto the audio connection through the KVM? To test this, try
plugging the audio directly into your main PC without it being switched
by the KVM, and without letting the audio leads come anywhere near the
KVM &/or BT Rec'r. My guess is that doing so will remove the hash.

[If not, I can't imagine how all this would be happening given the tests
that you've already described, so I won't bother to think about that
possibility until you've actually done a test to show that such a
rethink is actually necessary :-)]

> I thought it could be a radiation issue so
> fitted an extension USB cable and wound three turns of it into a
> substantial ferrite tube but it made no difference.
> My previous M$ Desktop 2000 was connected in exactly the same
> configuration and was never a problem.

I wonder what would happen if you did that to the audio output cable?
It would probably mess with the FR of the sound, and wouldn't be ideal
as a permanent arrangement, but might be interesting as a test, to see
if & how it alters the sound being produced? Also, if my theory is
correct and if you tried it on both the audio input and output in turn,
putting it on the input should make little or no difference to the sound
of the hash itself, but putting it on the output should change its sound
somehow.

> Methinks an email to Cherry might be appropriate?

If plugging the audio directly into the PC removes it, then it's more of
a KVM problem that has only just come to light because of the change of
hardware attached to it, so maybe is not really the fault of the
keyboard & mouse. However, I suppose they could be partly to blame, in
that their receiver could be causing the USB input circuit in the KVM to
misbehave somehow, so you could try emailing Cherry to see what they
say. I suspect they would probably reply, at least initially, blaming
the KVM, and saying:
"Sorry, but not our problem!"

--

Fake news kills!

I may be contacted via the contact address given on my website:
www.macfh.co.uk

On Thu, 11 Jan 2024 15:44:42 +0000, Woody wrote:

> On Thu 11/01/2024 15:05, Bob Eager wrote:
>> On Thu, 11 Jan 2024 14:51:16 +0000, Woody wrote:
>>
>>> If anyone has polite suggestions of a cure, or a reasonably priced KM
>>> or KVM HDMI switch I would be most obliged.
>>
>> I am very impressed with all of the ATEN KVMUA switches I have had,
>> four different models in various places. I currently have (and am using
>> right now) a two port one that does KVM plus USB and audio. No
>> problems, but it is all wired.
>
> Thanks for that Bob but unfortunately £80++ is a bit more than I wanted
> to pay - albeit the CS22H will do exactly what I want!!

I agree they are pricy. I had so much trouble with Belkin products that I
would never use them again. I have three two port ATENs, one four port
one, and one eight port one. All have performed faultlessly for years, and
you even get firmware upgrades. The KVMUA allows some customisation of
what happens when you switch, and allows selection of two possible hotkeys
for switching.

On Thu, 11 Jan 2024 22:57:04 +0000, Java Jive wrote:

> Rereading your OP and restated comments below, I missed that, I think,
> you're also switching analog audio output from the PCs via the KVM? Pls
> confirm, as otherwise I'm way off mark. The PRO models I described
> above don't have the connections to allow that, and, although the SOHo
> model did, I never actually did this except once to see if it actually
> worked, which of course it did. However, I've never wanted to do this
> on a permanent basis, because if I have media playing on one PC, I
> wouldn't want the sound to be interrupted while working on another.
> However, as always, your own needs are allowed to differ from mine!

The ATENs allow partial switching, in various configurations. So I can
keep the audio on from one source, but switch the rest. But then switch
the audio separately (or together) if I need to.

On Thu 11/01/2024 22:57, Java Jive wrote:
> On 11/01/2024 20:23, Woody wrote:
>> On Thu 11/01/2024 17:05, Java Jive wrote:
>>> On 11/01/2024 14:51, Woody wrote:
>>>>
>>>> Can anyone recommend me a KM or KVM switch with USB on board please?
>>>>
>>>> I have recently changed from a M$ Desktop (wireless mouse and
>>>> keyboard) to a Cherry Gentix equivalent and have just discovered
>>>> that the USB Bluetooth receiver plugged into my existing KVM switch
>>>> is generating a low level buzz on the audio feed to my speakers.
>>>> This never happened with the M$ kit but the keyboard was becoming
>>>> intermittent so I had no option - the M$ Desktop that I had is no
>>>> longer made it seems.)
>>>> After much pratting about I have discovered that if the BT Rx is
>>>> plugged directly into my main PC there is no buzz and audio is
>>>> reproduced perfectly. However if I plug the BT Rx into the KVM
>>>> switch I get the buzz.
>>>> I have two desktop PCs, one that is rarely used running XPSP3, and
>>>> my normal PC running W10Pro. As my (latest) monitor has two inputs
>>>> (HDMI and DisplayPort) I no longer need the video switching
>>>> capability but it is useful to have soft control of the keyboard and
>>>> mouse should I need to use the XP machine.
>>>> I have tried a longish USB extension cable on the BT Rx with three
>>>> turns passed through a ferrite bead but it makes no difference, the
>>>> buzz is still present.
>>>> I have tried everything in terms of hum loops etc but this is not a
>>>> 50Hz or 100Hz hum, more a buzz which sounds like USB clock getting
>>>> onto the supply wires in the cables. Using the soft switch to change
>>>> over to the XP3 machine (switched off but connected to main) kills
>>>> the buzz.
>>>>
>>>> If anyone has polite suggestions of a cure, or a reasonably priced
>>>> KM or KVM HDMI switch I would be most obliged.
>>>
>>> If you can find an alternative PSU of the same rating and polarity
>>> for the KVM, try swapping that in to see if that fixes the hash.
>>>
>>> I use two KVMs, one in normal use, the other as a backup ...
>>>
>>> The one currently in normal use is a Belkin OmniView PRO3 16-Port KVM
>>> Switch, USB/PS2 + VGA, which I bought second-hand/used for £25 inc
>>> p&p, a lucky find on eBay.
>>>
>>> Previously I paid £40 + surcharge of £7 p&p* for 2 x Belkin OmniView
>>> PRO2 + 1 x Belkin OmniView PRO3, all 4-port, + an assortment of
>>> cables. One of the PRO2 was an older model, PS2 only, and was faulty
>>> (magenta output, so green channel broken), the other I used to have
>>> daisy-chained to the PRO3 for my old tower W2k machines, but it
>>> became redundant when my monitor caught fire (literally, black smoke
>>> rising out of the back of it, I used welding gloves to carry it
>>> outside at arms' length).  The PRO3 worked for many years after but
>>> died in a thunderstorm last summer.
>>>
>>> The backup system is a 4-port USB-powered one with analog video, for
>>> around £10 excluding cables from eBay, but I can't find the original
>>> sale item now.
>>>
>>> Previous to all the above, I had a Belkin SOHo 4-Port model number
>>> now forgotten.
>>>
>>> All of the above have been in use with a Logitech MK520 wireless
>>> keyboard & mouse set, the keyboard model number seems to be K540, the
>>> mouse model number M310.  I still have an Amazon link, but it's no
>>> longer available, presumably because it is a superseded model:
>>> https://www.amazon.co.uk/dp/B003ZWL9G4/ref=pe_217191_31005151_3p_M3_dp_1
>>>
>>> None of the above combinations have caused me any interference on
>>> sound, and I play a lot of music through a Terratec USB sound-card on
>>> the end of a long USB lead to take it to the stereo the other side of
>>> this room.
>>>
>>>
>>> *  Something to which I wouldn't normally agree  -  I'm on the
>>> mainland, no ferries involved, so no more remote than some areas of
>>> Wales or Galloway in southern Scotland, which AFAIK don't incur extra
>>> charges for delivering there.
>
> Rereading your OP and restated comments below, I missed that, I think,
> you're also switching analog audio output from the PCs via the KVM?  Pls
> confirm, as otherwise I'm way off mark.  The PRO models I described
> above don't have the connections to allow that, and, although the SOHo
> model did, I never actually did this except once to see if it actually
> worked, which of course it did.  However, I've never wanted to do this
> on a permanent basis, because if I have media playing on one PC, I
> wouldn't want the sound to be interrupted while working on another.
> However, as always, your own needs are allowed to differ from mine!
>
>> The KVM switch that I have is powered from the PCs through USB, there
>> is no separate power supply. If I switch to the XP PC when it is
>> unpowered but still connected to the mains lead the buzz disappears.
>
> If my assumption above is correct, that is presumably because the XP
> machine, being switched off, is not acting as an audio source into the KVM.
>
>> If I unplug the audio input or output of the switch whilst selected on
>> the W10 machine the buzz disappears.
>
> Again because, like the XP machine being switched off, there is no audio
> coming into the KVM.
>
>> Most significantly if I unplug the BT receiver (mini USB) the buzz
>> also disappears.
>> Ergo I conclude that the receiver is radiating interference onto the
>> USB connection to the W10 PC.
>
> No, I don't think so, surely it's much more likely that hash is leaking
> directly onto the audio connection through the KVM?  To test this, try
> plugging the audio directly into your main PC without it being switched
> by the KVM, and without letting the audio leads come anywhere near the
> KVM &/or BT Rec'r.  My guess is that doing so will remove the hash.
>
> [If not, I can't imagine how all this would be happening given the tests
> that you've already described, so I won't bother to think about that
> possibility until you've actually done a test to show that such a
> rethink is actually necessary :-)]
>
>> I thought it could be a radiation issue so fitted an extension USB
>> cable and wound three turns of it into a substantial ferrite tube but
>> it made no difference.
>> My previous M$ Desktop 2000 was connected in exactly the same
>> configuration and was never a problem.
>
> I wonder what would happen if you did that to the audio output cable? It
> would probably mess with the FR of the sound, and wouldn't be ideal as a
> permanent arrangement, but might be interesting as a test, to see if &
> how it alters the sound being produced?  Also, if my theory is correct
> and if you tried it on both the audio input and output in turn, putting
> it on the input should make little or no difference to the sound of the
> hash itself, but putting it on the output should change its sound somehow.
>
>> Methinks an email to Cherry might be appropriate?
>
> If plugging the audio directly into the PC removes it, then it's more of
> a KVM problem that has only just come to light because of the change of
> hardware attached to it, so maybe is not really the fault of the
> keyboard & mouse.  However, I suppose they could be partly to blame, in
> that their receiver could be causing the USB input circuit in the KVM to
> misbehave somehow, so you could try emailing Cherry to see what they
> say.  I suspect they would probably reply, at least initially, blaming
> the KVM, and saying:
>     "Sorry, but not our problem!"
>
Confirm audio is switched by the KVM, and also confirm that the BT Rx
directly into the PC is as silent as the grave.

Maybe if I try Cherry I might perhaps use a little 'truth economy' per
the whole story and see how they respond. Of course the thing I haven't
look at is whether or not I can get into the KVM box and if I can then
maybe a bit of decoupling on the audio amp might have effect - I admit
the buzz level is quite low.

Failing that I will have to resort to prising the the keytops off my M$
keyboard and cleaning it out a bit - you wouldn't believe how much dust
accumulates in this house!! 8-))

Woody <harrogate3@ntlworld.com> wrote:
> On Thu 11/01/2024 22:57, Java Jive wrote:
>> On 11/01/2024 20:23, Woody wrote:
>>> On Thu 11/01/2024 17:05, Java Jive wrote:
>>>> On 11/01/2024 14:51, Woody wrote:
>>>>>
>>>>> Can anyone recommend me a KM or KVM switch with USB on board please?
>>>>>
>>>>> I have recently changed from a M$ Desktop (wireless mouse and
>>>>> keyboard) to a Cherry Gentix equivalent and have just discovered
>>>>> that the USB Bluetooth receiver plugged into my existing KVM switch
>>>>> is generating a low level buzz on the audio feed to my speakers.
>>>>> This never happened with the M$ kit but the keyboard was becoming
>>>>> intermittent so I had no option - the M$ Desktop that I had is no
>>>>> longer made it seems.)
>>>>> After much pratting about I have discovered that if the BT Rx is
>>>>> plugged directly into my main PC there is no buzz and audio is
>>>>> reproduced perfectly. However if I plug the BT Rx into the KVM
>>>>> switch I get the buzz.
>>>>> I have two desktop PCs, one that is rarely used running XPSP3, and
>>>>> my normal PC running W10Pro. As my (latest) monitor has two inputs
>>>>> (HDMI and DisplayPort) I no longer need the video switching
>>>>> capability but it is useful to have soft control of the keyboard and
>>>>> mouse should I need to use the XP machine.
>>>>> I have tried a longish USB extension cable on the BT Rx with three
>>>>> turns passed through a ferrite bead but it makes no difference, the
>>>>> buzz is still present.
>>>>> I have tried everything in terms of hum loops etc but this is not a
>>>>> 50Hz or 100Hz hum, more a buzz which sounds like USB clock getting
>>>>> onto the supply wires in the cables. Using the soft switch to change
>>>>> over to the XP3 machine (switched off but connected to main) kills
>>>>> the buzz.
>>>>>
>>>>> If anyone has polite suggestions of a cure, or a reasonably priced
>>>>> KM or KVM HDMI switch I would be most obliged.
>>>>
>>>> If you can find an alternative PSU of the same rating and polarity
>>>> for the KVM, try swapping that in to see if that fixes the hash.
>>>>
>>>> I use two KVMs, one in normal use, the other as a backup ...
>>>>
>>>> The one currently in normal use is a Belkin OmniView PRO3 16-Port KVM
>>>> Switch, USB/PS2 + VGA, which I bought second-hand/used for £25 inc
>>>> p&p, a lucky find on eBay.
>>>>
>>>> Previously I paid £40 + surcharge of £7 p&p* for 2 x Belkin OmniView
>>>> PRO2 + 1 x Belkin OmniView PRO3, all 4-port, + an assortment of
>>>> cables. One of the PRO2 was an older model, PS2 only, and was faulty
>>>> (magenta output, so green channel broken), the other I used to have
>>>> daisy-chained to the PRO3 for my old tower W2k machines, but it
>>>> became redundant when my monitor caught fire (literally, black smoke
>>>> rising out of the back of it, I used welding gloves to carry it
>>>> outside at arms' length).  The PRO3 worked for many years after but
>>>> died in a thunderstorm last summer.
>>>>
>>>> The backup system is a 4-port USB-powered one with analog video, for
>>>> around £10 excluding cables from eBay, but I can't find the original
>>>> sale item now.
>>>>
>>>> Previous to all the above, I had a Belkin SOHo 4-Port model number
>>>> now forgotten.
>>>>
>>>> All of the above have been in use with a Logitech MK520 wireless
>>>> keyboard & mouse set, the keyboard model number seems to be K540, the
>>>> mouse model number M310.  I still have an Amazon link, but it's no
>>>> longer available, presumably because it is a superseded model:
>>>> https://www.amazon.co.uk/dp/B003ZWL9G4/ref=pe_217191_31005151_3p_M3_dp_1
>>>>
>>>> None of the above combinations have caused me any interference on
>>>> sound, and I play a lot of music through a Terratec USB sound-card on
>>>> the end of a long USB lead to take it to the stereo the other side of
>>>> this room.
>>>>
>>>>
>>>> *  Something to which I wouldn't normally agree  -  I'm on the
>>>> mainland, no ferries involved, so no more remote than some areas of
>>>> Wales or Galloway in southern Scotland, which AFAIK don't incur extra
>>>> charges for delivering there.
>>
>> Rereading your OP and restated comments below, I missed that, I think,
>> you're also switching analog audio output from the PCs via the KVM?  Pls
>> confirm, as otherwise I'm way off mark.  The PRO models I described
>> above don't have the connections to allow that, and, although the SOHo
>> model did, I never actually did this except once to see if it actually
>> worked, which of course it did.  However, I've never wanted to do this
>> on a permanent basis, because if I have media playing on one PC, I
>> wouldn't want the sound to be interrupted while working on another.
>> However, as always, your own needs are allowed to differ from mine!
>>
>>> The KVM switch that I have is powered from the PCs through USB, there
>>> is no separate power supply. If I switch to the XP PC when it is
>>> unpowered but still connected to the mains lead the buzz disappears.
>>
>> If my assumption above is correct, that is presumably because the XP
>> machine, being switched off, is not acting as an audio source into the KVM.
>>
>>> If I unplug the audio input or output of the switch whilst selected on
>>> the W10 machine the buzz disappears.
>>
>> Again because, like the XP machine being switched off, there is no audio
>> coming into the KVM.
>>
>>> Most significantly if I unplug the BT receiver (mini USB) the buzz
>>> also disappears.
>>> Ergo I conclude that the receiver is radiating interference onto the
>>> USB connection to the W10 PC.
>>
>> No, I don't think so, surely it's much more likely that hash is leaking
>> directly onto the audio connection through the KVM?  To test this, try
>> plugging the audio directly into your main PC without it being switched
>> by the KVM, and without letting the audio leads come anywhere near the
>> KVM &/or BT Rec'r.  My guess is that doing so will remove the hash.
>>
>> [If not, I can't imagine how all this would be happening given the tests
>> that you've already described, so I won't bother to think about that
>> possibility until you've actually done a test to show that such a
>> rethink is actually necessary :-)]
>>
>>> I thought it could be a radiation issue so fitted an extension USB
>>> cable and wound three turns of it into a substantial ferrite tube but
>>> it made no difference.
>>> My previous M$ Desktop 2000 was connected in exactly the same
>>> configuration and was never a problem.
>>
>> I wonder what would happen if you did that to the audio output cable? It
>> would probably mess with the FR of the sound, and wouldn't be ideal as a
>> permanent arrangement, but might be interesting as a test, to see if &
>> how it alters the sound being produced?  Also, if my theory is correct
>> and if you tried it on both the audio input and output in turn, putting
>> it on the input should make little or no difference to the sound of the
>> hash itself, but putting it on the output should change its sound somehow.
>>
>>> Methinks an email to Cherry might be appropriate?
>>
>> If plugging the audio directly into the PC removes it, then it's more of
>> a KVM problem that has only just come to light because of the change of
>> hardware attached to it, so maybe is not really the fault of the
>> keyboard & mouse.  However, I suppose they could be partly to blame, in
>> that their receiver could be causing the USB input circuit in the KVM to
>> misbehave somehow, so you could try emailing Cherry to see what they
>> say.  I suspect they would probably reply, at least initially, blaming
>> the KVM, and saying:
>>     "Sorry, but not our problem!"
>>
> Confirm audio is switched by the KVM, and also confirm that the BT Rx
> directly into the PC is as silent as the grave.
>
> Maybe if I try Cherry I might perhaps use a little 'truth economy' per
> the whole story and see how they respond. Of course the thing I haven't
> look at is whether or not I can get into the KVM box and if I can then
> maybe a bit of decoupling on the audio amp might have effect - I admit
> the buzz level is quite low.
>
> Failing that I will have to resort to prising the the keytops off my M$
> keyboard and cleaning it out a bit - you wouldn't believe how much dust
> accumulates in this house!! 8-))
>
> Thanks for your input.
>
>
>

On 11 Jan 2024 15:44, Woody wrote:
> On Thu 11/01/2024 15:05, Bob Eager wrote:
>> On Thu, 11 Jan 2024 14:51:16 +0000, Woody wrote:
>>
>>> If anyone has polite suggestions of a cure, or a reasonably priced KM or
>>> KVM HDMI switch I would be most obliged.
>>
>> I am very impressed with all of the ATEN KVMUA switches I have had, four
>> different models in various places. I currently have (and am using right
>> now) a two port one that does KVM plus USB and audio. No problems, but it
>> is all wired.
>
> Thanks for that Bob but unfortunately £80++ is a bit more than I wanted
> to pay - albeit the CS22H will do exactly what I want!!
>

I have a 3-port (was 4-port but one has lost a VGA pin) ATEN VGA/USB
switch you are welcome to collect from Queen Adelaide.

On Fri 12/01/2024 07:59, Tweed wrote:
> Woody <harrogate3@ntlworld.com> wrote:
>> On Thu 11/01/2024 22:57, Java Jive wrote:
>>> On 11/01/2024 20:23, Woody wrote:
>>>> On Thu 11/01/2024 17:05, Java Jive wrote:
>>>>> On 11/01/2024 14:51, Woody wrote:
>>>>>>
>>>>>> Can anyone recommend me a KM or KVM switch with USB on board please?
>>>>>>
>>>>>> I have recently changed from a M$ Desktop (wireless mouse and
>>>>>> keyboard) to a Cherry Gentix equivalent and have just discovered
>>>>>> that the USB Bluetooth receiver plugged into my existing KVM switch
>>>>>> is generating a low level buzz on the audio feed to my speakers.
>>>>>> This never happened with the M$ kit but the keyboard was becoming
>>>>>> intermittent so I had no option - the M$ Desktop that I had is no
>>>>>> longer made it seems.)
>>>>>> After much pratting about I have discovered that if the BT Rx is
>>>>>> plugged directly into my main PC there is no buzz and audio is
>>>>>> reproduced perfectly. However if I plug the BT Rx into the KVM
>>>>>> switch I get the buzz.
>>>>>> I have two desktop PCs, one that is rarely used running XPSP3, and
>>>>>> my normal PC running W10Pro. As my (latest) monitor has two inputs
>>>>>> (HDMI and DisplayPort) I no longer need the video switching
>>>>>> capability but it is useful to have soft control of the keyboard and
>>>>>> mouse should I need to use the XP machine.
>>>>>> I have tried a longish USB extension cable on the BT Rx with three
>>>>>> turns passed through a ferrite bead but it makes no difference, the
>>>>>> buzz is still present.
>>>>>> I have tried everything in terms of hum loops etc but this is not a
>>>>>> 50Hz or 100Hz hum, more a buzz which sounds like USB clock getting
>>>>>> onto the supply wires in the cables. Using the soft switch to change
>>>>>> over to the XP3 machine (switched off but connected to main) kills
>>>>>> the buzz.
>>>>>>
>>>>>> If anyone has polite suggestions of a cure, or a reasonably priced
>>>>>> KM or KVM HDMI switch I would be most obliged.
>>>>>
>>>>> If you can find an alternative PSU of the same rating and polarity
>>>>> for the KVM, try swapping that in to see if that fixes the hash.
>>>>>
>>>>> I use two KVMs, one in normal use, the other as a backup ...
>>>>>
>>>>> The one currently in normal use is a Belkin OmniView PRO3 16-Port KVM
>>>>> Switch, USB/PS2 + VGA, which I bought second-hand/used for £25 inc
>>>>> p&p, a lucky find on eBay.
>>>>>
>>>>> Previously I paid £40 + surcharge of £7 p&p* for 2 x Belkin OmniView
>>>>> PRO2 + 1 x Belkin OmniView PRO3, all 4-port, + an assortment of
>>>>> cables. One of the PRO2 was an older model, PS2 only, and was faulty
>>>>> (magenta output, so green channel broken), the other I used to have
>>>>> daisy-chained to the PRO3 for my old tower W2k machines, but it
>>>>> became redundant when my monitor caught fire (literally, black smoke
>>>>> rising out of the back of it, I used welding gloves to carry it
>>>>> outside at arms' length).  The PRO3 worked for many years after but
>>>>> died in a thunderstorm last summer.
>>>>>
>>>>> The backup system is a 4-port USB-powered one with analog video, for
>>>>> around £10 excluding cables from eBay, but I can't find the original
>>>>> sale item now.
>>>>>
>>>>> Previous to all the above, I had a Belkin SOHo 4-Port model number
>>>>> now forgotten.
>>>>>
>>>>> All of the above have been in use with a Logitech MK520 wireless
>>>>> keyboard & mouse set, the keyboard model number seems to be K540, the
>>>>> mouse model number M310.  I still have an Amazon link, but it's no
>>>>> longer available, presumably because it is a superseded model:
>>>>> https://www.amazon.co.uk/dp/B003ZWL9G4/ref=pe_217191_31005151_3p_M3_dp_1
>>>>>
>>>>> None of the above combinations have caused me any interference on
>>>>> sound, and I play a lot of music through a Terratec USB sound-card on
>>>>> the end of a long USB lead to take it to the stereo the other side of
>>>>> this room.
>>>>>
>>>>>
>>>>> *  Something to which I wouldn't normally agree  -  I'm on the
>>>>> mainland, no ferries involved, so no more remote than some areas of
>>>>> Wales or Galloway in southern Scotland, which AFAIK don't incur extra
>>>>> charges for delivering there.
>>>
>>> Rereading your OP and restated comments below, I missed that, I think,
>>> you're also switching analog audio output from the PCs via the KVM?  Pls
>>> confirm, as otherwise I'm way off mark.  The PRO models I described
>>> above don't have the connections to allow that, and, although the SOHo
>>> model did, I never actually did this except once to see if it actually
>>> worked, which of course it did.  However, I've never wanted to do this
>>> on a permanent basis, because if I have media playing on one PC, I
>>> wouldn't want the sound to be interrupted while working on another.
>>> However, as always, your own needs are allowed to differ from mine!
>>>
>>>> The KVM switch that I have is powered from the PCs through USB, there
>>>> is no separate power supply. If I switch to the XP PC when it is
>>>> unpowered but still connected to the mains lead the buzz disappears.
>>>
>>> If my assumption above is correct, that is presumably because the XP
>>> machine, being switched off, is not acting as an audio source into the KVM.
>>>
>>>> If I unplug the audio input or output of the switch whilst selected on
>>>> the W10 machine the buzz disappears.
>>>
>>> Again because, like the XP machine being switched off, there is no audio
>>> coming into the KVM.
>>>
>>>> Most significantly if I unplug the BT receiver (mini USB) the buzz
>>>> also disappears.
>>>> Ergo I conclude that the receiver is radiating interference onto the
>>>> USB connection to the W10 PC.
>>>
>>> No, I don't think so, surely it's much more likely that hash is leaking
>>> directly onto the audio connection through the KVM?  To test this, try
>>> plugging the audio directly into your main PC without it being switched
>>> by the KVM, and without letting the audio leads come anywhere near the
>>> KVM &/or BT Rec'r.  My guess is that doing so will remove the hash.
>>>
>>> [If not, I can't imagine how all this would be happening given the tests
>>> that you've already described, so I won't bother to think about that
>>> possibility until you've actually done a test to show that such a
>>> rethink is actually necessary :-)]
>>>
>>>> I thought it could be a radiation issue so fitted an extension USB
>>>> cable and wound three turns of it into a substantial ferrite tube but
>>>> it made no difference.
>>>> My previous M$ Desktop 2000 was connected in exactly the same
>>>> configuration and was never a problem.
>>>
>>> I wonder what would happen if you did that to the audio output cable? It
>>> would probably mess with the FR of the sound, and wouldn't be ideal as a
>>> permanent arrangement, but might be interesting as a test, to see if &
>>> how it alters the sound being produced?  Also, if my theory is correct
>>> and if you tried it on both the audio input and output in turn, putting
>>> it on the input should make little or no difference to the sound of the
>>> hash itself, but putting it on the output should change its sound somehow.
>>>
>>>> Methinks an email to Cherry might be appropriate?
>>>
>>> If plugging the audio directly into the PC removes it, then it's more of
>>> a KVM problem that has only just come to light because of the change of
>>> hardware attached to it, so maybe is not really the fault of the
>>> keyboard & mouse.  However, I suppose they could be partly to blame, in
>>> that their receiver could be causing the USB input circuit in the KVM to
>>> misbehave somehow, so you could try emailing Cherry to see what they
>>> say.  I suspect they would probably reply, at least initially, blaming
>>> the KVM, and saying:
>>>     "Sorry, but not our problem!"
>>>
>> Confirm audio is switched by the KVM, and also confirm that the BT Rx
>> directly into the PC is as silent as the grave.
>>
>> Maybe if I try Cherry I might perhaps use a little 'truth economy' per
>> the whole story and see how they respond. Of course the thing I haven't
>> look at is whether or not I can get into the KVM box and if I can then
>> maybe a bit of decoupling on the audio amp might have effect - I admit
>> the buzz level is quite low.
>>
>> Failing that I will have to resort to prising the the keytops off my M$
>> keyboard and cleaning it out a bit - you wouldn't believe how much dust
>> accumulates in this house!! 8-))
>>
>> Thanks for your input.
>>
>>
>>
>
> Would running the XP machine as a virtual machine inside the Win10 computer
> be a solution?
>

On 11/01/2024 23:28, Woody wrote:
> On Thu 11/01/2024 22:57, Java Jive wrote:
>> On 11/01/2024 20:23, Woody wrote:
>>> On Thu 11/01/2024 17:05, Java Jive wrote:
>>>> On 11/01/2024 14:51, Woody wrote:
>>>
>>> Most significantly if I unplug the BT receiver (mini USB) the buzz
>>> also disappears.
>>> Ergo I conclude that the receiver is radiating interference onto the
>>> USB connection to the W10 PC.
>>
>> No, I don't think so, surely it's much more likely that hash is
>> leaking directly onto the audio connection through the KVM?  To test
>> this, try plugging the audio directly into your main PC without it
>> being switched by the KVM, and without letting the audio leads come
>> anywhere near the KVM &/or BT Rec'r.  My guess is that doing so will
>> remove the hash.

You didn't answer this, so we're none the wiser as to whether my guess
is correct.

> Confirm audio is switched by the KVM

Got there in the end, then, apologies for not spotting that in your OP.

--

Fake news kills!

I may be contacted via the contact address given on my website:
www.macfh.co.uk

On 11/01/2024 14:51, Woody wrote:
>
> Can anyone recommend me a KM or KVM switch with USB on board please?
>
> I have recently changed from a M$ Desktop (wireless mouse and keyboard)
> to a Cherry Gentix equivalent and have just discovered that the USB
> Bluetooth receiver plugged into my existing KVM switch is generating a
> low level buzz on the audio feed to my speakers. This never happened
> with the M$ kit but the keyboard was becoming intermittent so I had no
> option - the M$ Desktop that I had is no longer made it seems.)
> After much pratting about I have discovered that if the BT Rx is plugged
> directly into my main PC there is no buzz and audio is reproduced
> perfectly. However if I plug the BT Rx into the KVM switch I get the buzz.
> I have two desktop PCs, one that is rarely used running XPSP3, and my
> normal PC running W10Pro. As my (latest) monitor has two inputs (HDMI
> and DisplayPort) I no longer need the video switching capability but it
> is useful to have soft control of the keyboard and mouse should I need
> to use the XP machine.

Belkin Omniview PRO2 are plentiful second-hand, and work well.

look for
F1DA104T
F1DA108T
F1DA116T

I've bought 3 units for less than £20, and if they mess up the video
then it's a relatively easy job changing worn electrolytic capacitors.
You will only need a VGA extension M-F cable, and USB A-B leads (type
commonly used for printers)

One, I was bold enough to buy it "sold for parts only" and fix it.

--
Adrian C

In message <unov97$31bjo$1@dont-email.me>, Woody
<harrogate3@ntlworld.com> writes
>
>Can anyone recommend me a KM or KVM switch with USB on board please?
>
>I have recently changed from a M$ Desktop (wireless mouse and keyboard)
>to a Cherry Gentix equivalent and have just discovered that the USB
>Bluetooth receiver plugged into my existing KVM switch is generating a
>low level buzz on the audio feed to my speakers. This never happened
>with the M$ kit but the keyboard was becoming intermittent so I had no
>option - the M$ Desktop that I had is no longer made it seems.)
>After much pratting about I have discovered that if the BT Rx is
>plugged directly into my main PC there is no buzz and audio is
>reproduced perfectly. However if I plug the BT Rx into the KVM switch I
>get the buzz.
>I have two desktop PCs, one that is rarely used running XPSP3, and my
>normal PC running W10Pro. As my (latest) monitor has two inputs (HDMI
>and DisplayPort) I no longer need the video switching capability but it
>is useful to have soft control of the keyboard and mouse should I need
>to use the XP machine.
>I have tried a longish USB extension cable on the BT Rx with three
>turns passed through a ferrite bead but it makes no difference, the
>buzz is still present.
>I have tried everything in terms of hum loops etc but this is not a
>50Hz or 100Hz hum, more a buzz which sounds like USB clock getting onto
>the supply wires in the cables. Using the soft switch to change over to
>the XP3 machine (switched off but connected to main) kills the buzz.
>
>If anyone has polite suggestions of a cure, or a reasonably priced KM
>or KVM HDMI switch I would be most obliged.

Have you considered using a VNC rather than a KVM. I use TightVNC
(free!) to control a headless Win 11 box from a Win10 desktop. Works
fine.
Install the server on the box you want to control, and the client on the
desktop.
--
Invalid