A surprising 'solution' to a vexing problem :-)

Thread Starter

Hypatia's Protege

Joined Mar 1, 2015
3,228
Kind friends...

I offer this in hopes that someone will find it useful or interesting - 'Entertaining' is ok too inasmuch as I'm a 'happy camper' now my longstanding problem is solved:D...

So... For over a year I've been experiencing difficulties with my home wireless network despite recourse to a large variety of routers, after-market antennae, external amplifiers, etc...

Today I got a 'break' when my housekeeper inquired as to why an 'unplugged' florescent 'work lamp' flickered whenever she heated her coffee -- The below attached image neatly answers her question and explains my problem:cool:

Despite the existence of a 'second bottom' fashioned of a louvered and otherwise perforated piece of sheet steel - the leakage manifested as a prominent 'lobe' extending from the front and right of the appliance and registering as 'excessive' (CIP 'pegged' at > 10mW/cm^2) upon a certified 'microwave oven survey meter' to a distance of some 12 feeto_O (said instrument being an intentionally rather 'deaf' passive field strength indicator)...

Four "takeaways":

1)
Despite what passes for 'conventional wisdom', magnetrons operating on "ISM 7" (Fc= 2.450 GHz) can and do disrupt digital networks operating on the same band - and, I might add, at considerable distance (to over 400 yards)...

2) While the 'swept' nature of the 'signal' issuing from leaky RF heating devices equipped with conventional PSUs (i.e. magnetic transformer+doubler) does not preclude interference with digital communications equipment, it essentially 'masks' itself from 'standard' UHF/SHF 'fox hunting' gear:mad:

3) Should you choose to employ on-premises staff, you may save yourself a great deal of agro (to say nothing of fire insurance premiums) via provision of furnished quarters (with emphasis upon appliances).

4) Whoever 'Emerson' is they (To render John Cleese), deserve a 'thorough, rollicking spanking':mad:;););)

Now I've several trenchers of crow awaiting my 'attentions' on multiple (especially) D-link review fora:oops::(

OBTW -- To any readers from the 'old country' (UK) -- Please investigate the phrase 'happy camper' as apparent in American slang prior to drawing conclusions!:eek::D

WonkyMW.jpg

Best regards
HP:)
 
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Thread Starter

Hypatia's Protege

Joined Mar 1, 2015
3,228
I tend to think a wifi phone app (wifi analyzer) might detect abnormal activity on all eleven channels. It could be a nice simple test ...
Trouble is the 120Hz 'ripple' FMs and AMs the output in such a way as to create a 'faux noise floor', if you will -- Just for 'fun' I'll hold on to the offending device with the aim of researching a 'detection method' - I don't own a smartphone (long story:rolleyes:) however nearly everyone with whom I'm acquainted does:cool: So... Do you have a link or info as to where said App might be found?:)

Best regards
HP:cool:
 

Thread Starter

Hypatia's Protege

Joined Mar 1, 2015
3,228
From the state of your microwave oven you should change your housekeeper, or get a new microwave!
Actually, I bought her a new one featuring a (gasp!) 'inverter technology' PSU:)-- Twas the least I could do in exchange for her (albeit it inadvertent) identification of the source of my 'WIFI woes':cool: -- As regards the defective unit, I have no knowledge of its history nor how it came to be so heavily corroded:confused: - I know Ms B. is partial to strong java but...?:eek:

Best regards
HP:)
 
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RichardO

Joined May 4, 2013
2,270
When I bought a brand new microwave oven many years ago it interferred with the old vacuum tube TV. I was not completely surprised since the tuner (and maybe other circuits) was missing a shield.

Just before the microwave oven warranty expired the oven failed. When I say "just before" I mean it literally. The warranty expired in the few days it took the repair to be scheduled. The repairman came out and did his thing which I suspect involved replacing the magnetron. Lo and behold , no more interference with the TV.

I am guessing that there was a high voltage arc from day one and that got fixed for free when the other repair was done.
 

Thread Starter

Hypatia's Protege

Joined Mar 1, 2015
3,228
I am guessing that there was a high voltage arc from day one and that got fixed for free when the other repair was done.
That makes sense inasmuch as (IIRC) the 'highest' (UHF) TV channel (under the old 70 channel allocation schedule) was centered about 888 MHz...

It has been my observation that even a slight burr in the waveguide or a loose (or otherwise poorly mounted) tube may result in arcing which (in addition to functioning as a "DC to daylight" noise source:mad:) may, in the latter case, eventually 'pierce' the tube -- Out of curiosity what was the failure presentation? Did the appliance 'run' sans heating or simply 'short out'?

Very best regards
HP:)
 
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RichardO

Joined May 4, 2013
2,270
That makes sense inasmuch as (IIRC) the 'highest' (UHF) TV channel (under the old 70 channel allocation schedule) was centered about 888 MHz...

It has been my observation that even a slight burr in the waveguide or a loose (or otherwise poorly mounted) tube may result in arcing which (in addition to functioning as a "DC to daylight" noise source:mad:) may, in the latter case, eventually 'pierce' tube -- Out of curiosity what was the failure presentation? Did the appliance 'run' sans heating or simply 'short out'?

Very best regards
HP:)
I think the interference was on all of the channels -- that is why is suspect an arc. The interference caused a band on the TV screen as the power to the magnetron was turned on and off during the cooking cycle. As I remember it the oven failed to heat at all.

I said above that I thought the magnetron failed but on thinking about it some more, maybe the power supply failed because of arcing.

p.s. I am still using the oven. The only repair that I have done is to clean grease out of the on/off switch. I guess in an oven that is probably 40 yeas old, a very fine grease mist could have taken a real long time to foul the switch. The bell no longer rings as loud as I would like. Probably some more of the grease at work.
 

Thread Starter

Hypatia's Protege

Joined Mar 1, 2015
3,228
the interference caused a band on the TV screen
FWIW I too have noted the appearance of horizontal 'interference bars' on TV receivers corollary to line-modulated RF noise -- I assume it's to do with 'heterodyne phenomena' in relation to the vertical deflection signal{s}...

As I remember it the oven failed to heat at all.
maybe the power supply failed because of arcing.
Indeed... Either an open rectifier or a magnetron 'gone to air' seems a likely diagnosis...

I guess in an oven that is probably 40 yeas old
Is it an Amana 'Radar Range' unit? -- I was most favorably impressed with the 'antique' (late 60's/mid 70's vintage) 'Radar Range' ovens seen at a swap-fest:) - Constructed like a bank vault and featuring heavy gauge non-magnetic stainless cooking chambers!:cool: I got a charge (NPI:eek:) out of the auto-locking door (considering said units likewise featured all currently required safety interlocks):confused::)

Very best regards
HP:)
 

Thread Starter

Hypatia's Protege

Joined Mar 1, 2015
3,228
This I could have confirmed for you, had you asked.
You might be surprised at the number of so-called 'experts' whom advise that WIFI's DS algorithm renders it wonderfully 'immune' to such interferenceo_O:rolleyes:...
For my part, I've long-since decided that the re-education of 'educated' idiots (i.e. the active kernels of Quora and Stack Exchange) is not a 'hill I'm willing to die upon'!:rolleyes::rolleyes::rolleyes:

Very best regards
HP:)
 

RichardO

Joined May 4, 2013
2,270
Is it an Amana 'Radar Range' unit? -- I was most favorably impressed with the 'antique' (late 60's/mid 70's vintage) 'Radar Range' ovens seen at a swap-fest:) - Constructed like a bank vault and featuring heavy gauge non-magnetic stainless cooking chambers!:cool: I got a charge (NPI:eek:) out of the auto-locking door (considering said units likewise featured all currently required safety interlocks):confused::)

Very best regards
HP:)
It is a stand-alone box that was sold by Sears. I am not sure who actually manufactured it. It weighs a ton so I avoid taking it off the high shelf I have it on unless I _really_ need to repair it.

I suspect that you would like reading a book about the history of radar and microwave ovens. The early history of the magnetron is especially interesting.
https://www.amazon.com/Invention-That-Changed-World-Revolution/dp/0684835290
 

Aleph(0)

Joined Mar 14, 2015
597
Today I got a 'break' when my housekeeper inquired as to why an 'unplugged' florescent 'work lamp' flickered whenever she heated her coffee -- The below attached image neatly answers her question and explains my problem:cool:
HP That's just lame! Carousel had to be jammed cuz of hole in floor so she just ran it anyway:confused::rolleyes:! HP You know I like Mrs. B. even if she does remind me way too much of Huma Abedin:eek: But she's too smart to act so stupidly! HP that could have caused fire just cuz she's too cheep to buy quality MW or even replace rusted out junk!

HP now I'm going to tell you something! You should document that leaking MW was hers and she brought it on to property! Cuz otherwise next thing you know you could be paying for her _phaco_ procedure too:mad:! HP if I know you she'd guilt you into it anyway:rolleyes: HP you know I'm not cold hearted but I say ppl have to learn a lesson when they do totally negligent things! HP it's not like a _slip_ that can happen to anyone cuz like you said it was going on for more than a yearo_O!

why an 'unplugged' florescent 'work lamp' flickered whenever she heated her coffee
HP How far away was lamp? I say you should do experiment to see how far away you can get like f40t12 tube to light:)!

the leakage manifested as a prominent 'lobe' extending from the front and right of the appliance and registering as 'excessive' (CIP 'pegged' at > 10mW/cm^2) upon a certified 'microwave oven survey meter' to a distance of some 12 feeto_O
HP does that mean reading came on scale at 12' or just that you got stopped by wall in that direction?

3) Should you choose to employ on-premises staff, you may save yourself a great deal of agro (to say nothing of fire insurance premiums) via provision of furnished quarters (with emphasis upon appliances).
HP you're right abt that but I say you should still inspect appliances regularly:rolleyes:!

I tend to think a wifi phone app (wifi analyzer) might detect abnormal activity on all eleven channels. It could be a nice simple test ...
JoeJester that sounds worth a try but I say HP needs to get a new phone without important data just for that cuz strong field strength can _scribble_ ram and toast electronics:eek:!

For my part, I've long-since decided that the re-education of 'educated' idiots (i.e. the active kernels of Quora and Stack Exchange) is not a 'hill I'm willing to die upon'!:rolleyes::rolleyes::rolleyes:
HP you sure can say that again:rolleyes:! I say they should merge and call it "Quack Exchange":rolleyes:!

I know Ms B. is partial to strong java but...?:eek:
But it took a year's worth of strong joe and a flashing florescent to finally wake her up:rolleyes:! HP is like I said you're just lucky there wasn't a fire!
 

Thread Starter

Hypatia's Protege

Joined Mar 1, 2015
3,228
That's just lame! Carousel had to be jammed cuz of hole in floor so she just ran it anyway:confused::rolleyes:!
Indeed - howbeit I'm certain you'll agree that we've all erred on the side of 'lameness' at one time or another...

HP You know I like Mrs. B. even if she does remind me way too much of Huma Abedin:eek:
Well... She certainly bears a strong physical resemblance to Ms Abedin -- Though I daresay she has far better taste in spouses (i.e. Curtis) -- to say nothing of employers!:eek::cool:

You should document that leaking MW was hers and she brought it on to property! Cuz otherwise next thing you know you could be paying for her _phaco_ procedure too:mad:!
Liability is a non-issue! -- My concern was with her health (I'll have my halo please!;)) - She is scheduled for a comprehensive ophthalmological exam even as I type! -- Inasmuch as she denies relevant symptoms, I very much doubt 'exceptional' findings are forthcoming:)

HP How far away was lamp?
It 'strikes' at up to four feet within the described 'lobe' -- Once 'ignited' a distance Ca. 8 feet is required to extinguish the arc..

I say you should do experiment to see how far away you can get like f40t12 tube to light:)!
Ya know... I wish you could find the time (for work on 'tutorial related' items) that you mistakenly believe I enjoy:rolleyes:

HP does that mean reading came on scale at 12' or just that you got stopped by wall in that direction?
The FS is down to ≈ 7.5 mW/cm^2 (maximum) at 12'...

HP you sure can say that again:rolleyes:! I say they should merge and call it "Quack Exchange":rolleyes:!
:D:D:D

But it took a year's worth of strong joe and a flashing florescent to finally wake her up:rolleyes:! HP is like I said you're just lucky there wasn't a fire!
But then there's my negligence with CRTs and your 'wonky' ULA engines! -- Point being, we're all guilty of stupid mistakes/oversights! -- Loyal employees are far too scarce to alienate over missteps for which they manifest remorse and embarrassment!

JoeJester that sounds worth a try but I say HP needs to get a new phone without important data just for that cuz strong field strength can _scribble_ ram and toast electronics:eek:!
The plan would to approach the 'leaky' unit from a safe distance with phone and a real FS indicator -- That said, your point is well taken!:)

Very best regards
HP:)
 
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JoeJester

Joined Apr 26, 2005
4,390
HP,

The mere fact that your wifi was compromised, the RFI had to exceed your desired signal. I'd like to say it probably 60 dB or more stronger than the WIFI.

I've used that analyzer to see what the signal strengtss were. You would be amazed how many wifi's occupy the same channel.
 

Thread Starter

Hypatia's Protege

Joined Mar 1, 2015
3,228
Hi, @JoeJester ! - Thanks for your continued interest/input!:)

The mere fact that your wifi was compromised, the RFI had to exceed your desired signal. I'd like to say it probably 60 dB or more stronger than the WIFI.
Aye! -- And the device upon which effects of the interference were most noted is located in Garret Lab (some 350 yards from the 'leaky' appliance, through considerable intervening masonry, wood and plaster):eek: -- Moreover, the (externally amplified) router is located a scant 60 yards from Garret Lab in the opposite direction of said leak!:eek: Although such would seem to afford the router a 34X 'advantage', I suspect 'wave guiding' (or other structurally-induced phenomena) are in play...?

While I know little to nothing of WIFI algorithms, I nonetheless find it curious that interference produces a 'weak' or 'no' signal condition:confused: -- Apparently the (Wireless LAN software's) signal-strength bar graph is an indication of demodulated signal quality - as opposed to carrier field-strength? While such would 'square' with my experience Re: BWEM (Spec DSSS) systems - I'm by no manner of being certain such is the 'mode' of WIFI? -- Then too, at the field strengths involved, perhaps it's a simple matter of 'front end' overload?

I've used that analyzer to see what the signal strengtss were. You would be amazed how many wifi's occupy the same channel.
I'm looking forward to giving it a try!:cool:

Very best regards
HP:)
 
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