Topic: Bad sensor....no biscuit!

[aweatherguy]

I just solved a very annoying problem. I have lots of OS sensors around the house and I started losing contact with almost all of them, all at once. It was intermittent and would come and go every few hours or so.

Finally tracked it down to a version 2.1 ultra-cold sensor with weak batteries. It was continuously transmitting an un-modulated carrier, and blocking all of the other sensor signals. The little red transmit LED in the sensor was continuously illuminated; that was the only indication that something was amiss. A change of batteries solved the problem.

I only found it because I had an ICOM handheld radio that I could tune to 433.92MHz. I walked around looking for where the signal was strongest. I don't know what I would have done w/o the radio...maybe just replace the batteries in every sensor.

I don't know if the version 3.0 sensors will do this with low batteries. But, if you suddenly lose contact with all your sensors, this would be one possibility to consider.

[nincehelser]

I only found it because I had an ICOM handheld radio that I could tune to 433.92MHz.

I've also found such a radio receiver valuable for debugging.

Does anyone know of a *cheap* (say, under $20) audio receiver a non-ham could use to monitor for traffic and interference on that frequency?

[aweatherguy]

I got the ICOM on sale (from Universal Radio maybe) for real cheap (couple hundred bucks if I recall). 150kHz to 1300MHz...a real bargain.

The only thing I know of in that price range would be low-end field strength meters. There's this at $30 but I have absolutely no idea how useful it would be:

http://www.mfjenterprises.com/Product.php?productid=MFJ-801

You can also search for "field strength meter" and find several articles for building one yourself.