microwave oven blues :(

philstar

hi there...

I have chorus digital, reception is fine, that is until someone starts using the microwave oven in the kitchen, then the picture goes distorted ...which is a pain in the ass.

So i just wanna know is there anyway of fixing this??

PS: i'm using top quality scart cables..

Sponge Bob

Its leaking, buy a new microwave.

watty

I'd get your wiring checked! Sounds like a voltage drop due to power used. If it's really interference from the oven you may all go blind. Get it checked for leakage!

Sponge Bob

If its a voltage drop then plug your hoover in where the microwave is plugged and turn it on and check your telly , if the same thing happens Watty is right . That may require an electrician to have a look. Its dodgy.

Otherwise its a leak or an internalised voltage drop maybe caused by shorting, either way get rid of that microwave.

philstar

Well come to think of it, its not just the microwave...i also get interference when someone is using a food processor, blender etc.

And its always been like that but before it wasn't as bad, but with digital its really noticeable.:(

do u guys not get the same trouble??

nicelives

philstar wrote:

Well come to think of it, its not just the microwave...i also get interference when someone is using a food processor, blender etc.

And its always been like that but before it wasn't as bad, but with digital its really noticeable.:(

do u guys not get the same trouble??

I've noticed when I'm watching ntl digital, it wrecks the microwave, frozen pizzas still cold in the middle, popcorn leaving loads of unpopped kernels, I'm sick of it and thinking of getting Sky.

paulm17781

nicelives wrote:

I've noticed when I'm watching ntl digital, it wrecks the microwave, frozen pizzas still cold in the middle, popcorn leaving loads of unpopped kernels, I'm sick of it and thinking of getting Sky.

I'm no electrician but I would be amazed if your digital box is affecting your microwave.

darkmaster2

paulm17781 wrote:

I'm no electrician but I would be amazed if your digital box is affecting your microwave.

Haha, It was a joke man

paulm17781

darkmaster2 wrote:

Haha, It was a joke man

You sure?

darkmaster2

paulm17781 wrote:

You sure?

Jaysus I hope so :eek:

nicelives

it was indeed, sorry should have put in the , it's like the canned laughter of boards

lucernarian

I am guessing that the OP has digital MMDS, which is close to microwave frequencies. If things with motors in them is affecting the signal too, then the cable going to the digital box might not be the best quality.

The cable must be good with ordinary cable or MMDS.

As for the voltage drop, how would that distort the picture?? We have bad voltage drops (i.e. turning on the shower brings mains voltage to ~205 Volts) but it only dims the lights.

Meh. I wonder how serious Watty was when he posted that...

philstar

To_be_confirmed wrote:

I am guessing that the OP has digital MMDS, which is close to microwave frequencies. If things with motors in them is affecting the signal too, then the cable going to the digital box might not be the best quality.

yes its mmds digital, the cable going from the aerial to the decoder is top notch and im also using top quality scart cables which i taught would fix it but ...no:(

PS the old mmds was never effected that much

Solair

Microwave ovens operate at about 2.45-2.5Ghz, very similar to MMDS. If your oven has developed a leak it's quite possible that your MMDS antenna or cabling is picking it up!

Is your MMDS antenna or cable located anywhere in proximity to the microwave?

Is the microwave old or was it very cheap? Or has it been subjected to any damage?
Check the interior of the oven for any rust, damaged paint work, or chipped paintwork.

It's quite possible that it's leaking some microwave energy. It's unlikely to be any major risk to you or your family as the intensity of the microwaves being leaked out won't be enough to do any damage. The only damage they can really do to you is heat you if you get too close to the source.

I would suggest that you have the microwave checked out by a competent repair person.

It's also possible the microwave has developed an electrical fault. They contain a fairly hefty transformer and some other high energy electrical components. If there are any faults it's quite possible that they'll create significant RF interference which could be messing up your MMDS reception too.

Again, it's not unusual that a microwave will interfere with equipment that uses those frequencies, but it shouldn't do so. There are RF shielding requirements and I would suggest that you get the microwave serviced or replaced.

We had a very similar problem in the US with a particular microwave and our cordless phone. The phone operated at 2.4Ghz, in common with many US cordless phones. When the microwave was running, there was a loud buzzing across the calls.

We got a better microwave. Problem solved!

Microwave ovens: Conventional microwave ovens operate within the 2.4-GHz ISM band. Microwave ovens are known to emit 1,000-1,200 watts of power within the heating chamber. Due to poor fabrication and RF shielding, however, RF energy can leak out of a microwave oven. As much as 10-dBm to 20-dBm power can be detected a couple of feet outside a microwave oven, sufficient enough to completely shut down the operation of a WLAN. Usually, the operation of a microwave oven can bring down performance by 75%-90% if the network operates in the same channel on which the microwave ovens works.

If your MMDS cabling is passing through the kitchen / near the microwave or, if you're in a bungalow and the antenna is located directly over the oven. It might be worth looking into.

It's one potentially big drawback to MMDS service!! There are lots of devices potentially using that spectrum. Including WiFi !!

http://en.wikipedia.org/wiki/ISM_band

Does the digital MMDS downconvert the signal from microwave frequencies at the settop box? Or is it down-converted at the antenna/masthead?

The analogue systems generally used standard analogue cable decoders, and the MMDS signals were down-converted at the masthead. The connection into the back of your settop box was just normal cable frequencies.

It's also possible that digital MMDS is more sensitive to major interference like that. i.e., rather than your signal just getting a bit snowy, some channels might freeze.

It does rather sound like the MMDS cable is poorly shielded.

What colour is the cable?
Can you see any codes printed on the cable itself? Could you possibly post them to this thread and we can let you know if it's appropriately shielded cable or not.

Antenna

He could try putting some chicken wire in the attic in between the microwave and the MMDS aerial?

repostion microwave elsewhere in room?

I'd also get it checked for excessive microwave leakage?
Until then avoid being near the microwave when its on!

Solair, MMDS is always downconverted (regardless of analogue/digital) as 2.5 GHz in say a 10m length of normal co-ax would be too lossy

Solair

Chicken wire won't filter microwaves out. They're too narrow.

You'd need a mesh which had a similar size grid to the one inside the glass door of your microwave.

However, aluminum foil "tin foil" would do the trick quite nicely!

Definitely get that microwave checked out though!

watty

The downlead is 218MHz to 400MHz, analogue or Digital MMDS. Like Satellite, the radio signal is converted at the dish. So if leaking microwave oven is getting that far you are all in danger of cateracts.

Many electronics gear works perfectly from 80V to 250V, some doesn't. I have seen computers reboot and distorted pictures on 200V .. 250V only gear (often a rear or internal switch for 110V mode) when an instant shower is used.

Prolonged microwave radiation of too high a level (i.e. standing near a Radar or leaking microwave oven ) has not yet conclusively shown to cause cancer, but cataracts is well known at Radar power levels (identical Transmitter components and similar frequency to Microwave oven).

You would never feel skin heat at microwave oven frequency. The heating would be internal and you would not feel it. A much higher frequency is needed for surface heating. The US military is tesing such a higher frequency device for "crowd control".

Fine chicken wire would block a lot of 2.5Ghz, but only if there was 100% coverage of the source, with all seams well connected at each hexagon.

philstar

the microwave is a top of the range panasonic...i don't its leaking.

the chicken-wire method how much of an area does it need to cover ??
have any of you guys tried it ??

watty

Complete enclosed.

Fine chicken wire would block a lot of 2.5Ghz, but only if there was 100% coverage of the source, with all seams well connected at each hexagon.

I don't care if it is a €5000 Neff. Stuff gets faults or is made wrong. Get it checked. Going blind with cateracts is not a good alternative.

paulm17781

philstar wrote:

Well come to think of it, its not just the microwave...i also get interference when someone is using a food processor, blender etc.

Surely this points to an electrical problem opposed to a microwave problem?

John1000

philstar wrote:

Well come to think of it, its not just the microwave...i also get interference when someone is using a food processor, blender etc.

And its always been like that but before it wasn't as bad, but with digital its really noticeable.:(

do u guys not get the same trouble??

It's hardly the microwave unless the food processor and blender are
emitting microwaves as well

Solair

In that case you it's most likely the shielding on your coax that's at fault.

watty

Yes. And/or a very weak signal too.

philstar

John1000 wrote:

It's hardly the microwave unless the food processor and blender are
emitting microwaves as well

sorry...that was my mistake, i do get interference from the food processor and blender but its different..just a line of static across the middle of the screen.

But the interference from the microwave is much more pronounced..the tv picture breaks up and becomes blocky.

Anyway surely in this day and age there must be some device on the market to stop/block this interference.:cool:

watty

Borrow a UPS for your TV and decoder box (Or about 80 Euro in Maplin for a "Trust") if it is a mains interference issue. Actually unplug the mains then try Microwave oven.

Are you using RF coax rather than SCART for Box to TV connection?

The tax man

Most times I've come across this problem is with central heating systems. When the timer kicked in you'd see the interference.No one would ever believe me until I'd hook up a TV to an inverter in my car(so separate power supply) and wait. When the heating kicked in again you'll see the interference on the TV plugged into the house mains,my TV running from the car had no problems. Most people got the idea and got a sparks out to fix things.
Seeing that you're getting interference from multiple appliances would make me believe you've got something wrong with the electrical wiring in the house. Generally it's a suppression failure linked to one item but not in your case. Maybe a bad earth somewhere in the wiring but it's something you'll probably need to get a sparks to check out.

philstar

i use scart for box to TV connection

scart is best yes ??

watty

Yes.


I'd agree with The Tax Man.

In fact I said it was either oven leaking or wiring at start.