Author Topic: Why you should never let anyone in your shop alone  (Read 7163 times)

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Offline Planobilly

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Why you should never let anyone in your shop alone
« on: September 03, 2016, 01:49:49 am »
I finished the  new build of a tube amp and a day or two later I turned the volume up and noticed it was oscillating. I worked for hours looking for the cause of the issue. After a while I looked like this  |O |O |O...lol :wtf:

A few days before AT&T installed a new internet router in my shop. They placed it under my workbench. I was not there at the time.

I finally found the router was the cause of all this greif. What a pain in the butt!!

The lessons learned were don't doubt yourself, if you know you did stuff right and rechecked your work then look for some other cause to the issue. Don't let anyone in your shop alone!!

Cheers,

Billy
 
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Online tautech

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Re: Why you should never let anyone in your shop alone
« Reply #1 on: September 03, 2016, 01:54:20 am »
That might suggest it doesn't meet EMI standards. Does it affect anything else close?
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Offline Planobilly

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Re: Why you should never let anyone in your shop alone
« Reply #2 on: September 03, 2016, 02:05:49 am »
Not after I killed it with my 12 gauge shot gun...lol

Just joking. I have not done any investigation yet but it will get moved somewhere else. I am not sure what the FCC standards for a router are.

Billy
 

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Re: Why you should never let anyone in your shop alone
« Reply #3 on: September 03, 2016, 02:08:06 am »
Not after I killed it with my 12 gauge shot gun...lol

Just joking. I have not done any investigation yet but it will get moved somewhere else. I am not sure what the FCC standards for a router are.

Billy
:-DD

Is it a combo LAN and wireless unit ?
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Offline jmctech

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Re: Why you should never let anyone in your shop alone
« Reply #4 on: September 03, 2016, 02:11:28 am »
The WiFi radio in some of the routers AT&T uses will cause an audible clicking noise in speakers also. I work for them, I have had to move a few routers for interference issues.

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Online tautech

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Re: Why you should never let anyone in your shop alone
« Reply #5 on: September 03, 2016, 02:14:48 am »
The WiFi radio in some of the routers AT&T uses will cause an audible clicking noise in speakers also. I work for them, I have had to move a few routers for interference issues.

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:palm:

How do you get away with installing devices that can do that?  :rant:
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Offline jmctech

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Re: Why you should never let anyone in your shop alone
« Reply #6 on: September 03, 2016, 02:15:59 am »
I have no clue I wondered the same thing

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Offline jmctech

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Re: Why you should never let anyone in your shop alone
« Reply #7 on: September 03, 2016, 02:22:05 am »
Which model is the modem that you have, I assumed it is the WiFi radio that causes the interference, most of the  power supplies for our modems are linear, but they might have smps in the modem causing the problem.

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« Last Edit: September 03, 2016, 02:23:43 am by jmctech »
 

Offline helius

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Re: Why you should never let anyone in your shop alone
« Reply #8 on: September 03, 2016, 02:50:12 am »
How do you get away with installing devices that can do that?  :rant:
For some reason the $3T GSM industry hasn't been shut down yet. I blame corrupt regulators.
 

Offline Ampera

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Re: Why you should never let anyone in your shop alone
« Reply #9 on: September 03, 2016, 06:33:41 am »
Over in Albany area we have FiOS who also did their own wireless routers.

When the people were there installing it the first thing we did was disable the modem's inbuilt router and used our own.

Rn we have 2 DIR-655 routers and a wireless AP.

And surprising enough our wireless network kinda sucks. 2.4 Ghz networking is stupid. I am aware as to why it's used, being FCC sanctioned for consumer use, but the 5.8 Ghz band has a ton more stable channels and supports faster 802.11 speeds.
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Offline CM800

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Re: Why you should never let anyone in your shop alone
« Reply #10 on: September 03, 2016, 06:39:20 am »
Would it have much effect reporting it to FCC?
 

Offline Ampera

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Re: Why you should never let anyone in your shop alone
« Reply #11 on: September 03, 2016, 06:48:28 am »
Would it have much effect reporting it to FCC?
Maybe, but probably not. Like most US divisions they don't do a whole load of case by case stuff and focus more on major issues. If this is major? Idk.
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Online tggzzz

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Re: Why you should never let anyone in your shop alone
« Reply #12 on: September 03, 2016, 07:54:40 am »
The WiFi radio in some of the routers AT&T uses will cause an audible clicking noise in speakers also. I work for them, I have had to move a few routers for interference issues.

Sent from my SAMSUNG-SM-N920A using Tapatalk
:palm:

How do you get away with installing devices that can do that?  :rant:

Probably because the transmitter is operating correctly, within specification and without generating EMI.

The principle is that RF is picked up by a wire near the audio system's input, and is rectified by a non-linear device such as a "rusty bolt" or a semiconductor junction. For a constant power RF signal, the result is a constant DC shift, which won't be heard. For a pulsed signal, the shift will be pulsed and that will be amplified and heard.

Classic example: the 217Hz ba-de-ba-de-ba-de-bzzzzz from a GSM cellphone near an old deafaid (absolutely deafening), or by any microphone such as another phone.

The audio interference falls off as somewhere between r4 and r8.
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Offline Howardlong

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Re: Why you should never let anyone in your shop alone
« Reply #13 on: September 03, 2016, 07:55:46 am »
Although I am not casting aspersions one way or the other, the balanced approach is to consider not only the intentional radiator's EMC, but also the EMC of the affected device.

I am sure there are many radio hams on this forum who have operated entirely legally, even on low power, who have at times unintentionally interfered with their own and their neighbours' electronics. Whether that is to do with the affected devices themselves, or, for modern consumer electronics, more often the installation itself, it can take some time to resolve, and needs a large dose of diplomacy.

Having your average cellphone anywhere near many particularly older consumer audio devices and landline phones causes clicks that we've all heard for example.

The natural reaction is understandably always to blame "what's changed", but sometimes the story isn't always as black and white as that.

Maybe the router is at fault, or maybe that tube amp needs a little attention spent on EMC!
« Last Edit: September 03, 2016, 07:58:17 am by Howardlong »
 
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Online tggzzz

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Re: Why you should never let anyone in your shop alone
« Reply #14 on: September 03, 2016, 07:56:41 am »
How do you get away with installing devices that can do that?  :rant:
For some reason the $3T GSM industry hasn't been shut down yet. I blame corrupt regulators.
That's mistaken. Blame physics and improperly shielded audio equipment.

See my previous message for the explanation.
There are lies, damned lies, statistics - and ADC/DAC specs.
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Online tggzzz

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Re: Why you should never let anyone in your shop alone
« Reply #15 on: September 03, 2016, 07:59:12 am »
Would it have much effect reporting it to FCC?

Absolutely none whatsoever. The problem is inadequately shielded audio equipment rectifying and then amplifying pulses of RF energy.
There are lies, damned lies, statistics - and ADC/DAC specs.
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Online tautech

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Re: Why you should never let anyone in your shop alone
« Reply #16 on: September 03, 2016, 08:04:14 am »
The WiFi radio in some of the routers AT&T uses will cause an audible clicking noise in speakers also. I work for them, I have had to move a few routers for interference issues.

Sent from my SAMSUNG-SM-N920A using Tapatalk
:palm:

How do you get away with installing devices that can do that?  :rant:

Probably because the transmitter is operating correctly, within specification and without generating EMI.

The principle is that RF is picked up by a wire near the audio system's input, and is rectified by a non-linear device such as a "rusty bolt" or a semiconductor junction. For a constant power RF signal, the result is a constant DC shift, which won't be heard. For a pulsed signal, the shift will be pulsed and that will be amplified and heard.

Classic example: the 217Hz ba-de-ba-de-ba-de-bzzzzz from a GSM cellphone near an old deafaid (absolutely deafening), or by any microphone such as another phone.

The audio interference falls off as somewhere between r4 and r8.
Yes of course.  :)
My old iPhone 4S interferes with the audio on my PC when close to it, normally when it's hand shaking to my cell provider just before a call or text arrives. Thanks excusable IMO but for a permanently installed modem I'm not so sure. Yeah, the junction example you provide, well that's almost impossible to prevent except to move stuff away.  :-/O
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Offline VK5RC

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Re: Why you should never let anyone in your shop alone
« Reply #17 on: September 03, 2016, 12:18:22 pm »
Transmitting 7Mhz at about 50W with my transmissions all 'by the book' (in terms of harmonic suppression etc) I could open my neighbours garage door (and close it fortunately). Luckily he was out at the time. Never went on 7MHz again until I moved. Diplomacy always wins. :-+
Lots of gear is not well RFI hardened esp the older or cheaper stuff.
Plasma TVs/crappy SWPSUs are deafening in RF terms often.
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Offline madires

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Re: Why you should never let anyone in your shop alone
« Reply #18 on: September 03, 2016, 01:12:26 pm »
Rn we have 2 DIR-655 routers and a wireless AP.

And surprising enough our wireless network kinda sucks. 2.4 Ghz networking is stupid. I am aware as to why it's used, being FCC sanctioned for consumer use, but the 5.8 Ghz band has a ton more stable channels and supports faster 802.11 speeds.

I wouldn't use D-Link's WLAN stuff. It simply sucks, even the more expensive "professional" stuff. Better get a TP-Link supported by OpenWrt. Much better and stable.
 
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Offline Planobilly

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Re: Why you should never let anyone in your shop alone
« Reply #19 on: September 03, 2016, 02:06:49 pm »
For me the answer to the issue is simple, just relocate the router. I am sure it will interfere with my scope and perhaps other equipment.

In hindsight, I should have moved the amp to another location. I did turn off the lights and the computer system. I have built and worked on many amps in this location without issue in the past. When starting up a new amp build for the first time, there is always the possibility of discovering issues with the build.

Not realizing the router was even there was the real issue. Normally, if I have some issue with an amp I am able to come to the solution pretty quickly. It is much easier to find a fault than come to the conclusion that everything is correctly built.

Tube amps are notorious for doing strange things and the causes are sometimes not so easy to find. I guess that fact had me running around in circles a lot longer than normal.

Billy
 

Offline Ampera

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Re: Why you should never let anyone in your shop alone
« Reply #20 on: September 03, 2016, 02:38:35 pm »
Rn we have 2 DIR-655 routers and a wireless AP.

And surprising enough our wireless network kinda sucks. 2.4 Ghz networking is stupid. I am aware as to why it's used, being FCC sanctioned for consumer use, but the 5.8 Ghz band has a ton more stable channels and supports faster 802.11 speeds.

I wouldn't use D-Link's WLAN stuff. It simply sucks, even the more expensive "professional" stuff. Better get a TP-Link supported by OpenWrt. Much better and stable.

The original DIR-655 802.11 N router was purchased by my dad who installed it to replace a god awful 802.11G router.

And yea, I know. But I got the second DIR-655 free from someone who said it broke (It didn't)

And while I would love to do so, routers aren't the sorta thing you can just get up and replace.
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Offline blueskull

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Re: Why you should never let anyone in your shop alone
« Reply #21 on: September 03, 2016, 02:47:23 pm »
If a certified and massively produced device interferes with your home brew amp, then most likely your amp or the installation worker is to be blamed.
Under some situations one compliant device may interfere another, but that only happens when the distance is too close that it is closer than regulation specified distance.
BTW, 2.4G is sometimes better than 5G, especially when you do not have line of sight. Also, in some countries like Japan, the use of 5G band outdoor is illegal.
If you want to cover your entire house with only one router, then you do not have a choice. Every solid thing blocks 5G signal.
 

Offline Cyberdragon

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Re: Why you should never let anyone in your shop alone
« Reply #22 on: September 03, 2016, 03:34:38 pm »
Put the router in the microwave. >:D

If the radio waves penetrate the device then it must not be FCC compliant, thus solving your problem. :-DD
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Offline Ampera

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Re: Why you should never let anyone in your shop alone
« Reply #23 on: September 03, 2016, 04:41:14 pm »
Good idea, but how do you plug it in?

Unless you mean to make a router panini.
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Offline System Error Message

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Re: Why you should never let anyone in your shop alone
« Reply #24 on: September 03, 2016, 06:46:13 pm »
i replaced all my networking equipment with my own, the modem, router, etc. When i replaced the ISP router with my own i lost 2ms of internet latency and thats significant. The router was very basic and seemed like it was well designed but it seems to have higher latencies than my modded 36 core router.

I've heard of the horrors of american telecoms like at&t and other providers. Cable ISPs are usually greedy giving you really bad upload-download ratios. If in the UK Virgin media is a prime example advertising a 10-1 ratio but in practice it is 20-1 in order to keep you content happy but unable to properly utilise the network for your own use like your own vpn, file and other services that routers nowadays support.
 


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