"Chris Hogg" wrote in message
...

On Fri, 27 Feb 2015 16:25:52 -0000, "Bertie Doe"
There are loads of these TM-902C available thru UK based suppliers but
expect to pay 3 or 4 quid more.

Before Easter, I must google the best soil temp for me seed potatoes :-)

Two tests for a thermocouple: does it read zero (or very close to it)
in a mix of ice and water that's been allowed to stand for a while,
and does it read close to 100 (or very close to it) when held in the
steam just down inside the spout of a boiling kettle (but not actually
in the boiling water)? If it meets those two tests, I'd be happy with
it.

I do have another K type which I bought on ebay for about 10 quid, 5 years
ago. It's the blue one in the following pics.

The 2-wire t/c supplied, sits permanently in the boiler of my espresso
machine. The s/s t/c probe is used for bread and yoghurt.

The cheapo (black) on will be kept in the allotment shed, it will be used on
soil and also checking g/house temps etc.

Freezing test. Didn't have an ice cube mould so used 4 x 100 ml yoghurt
pots. Perhaps if I'd hammered them into a slush, I may have got to Zero :-
https://www.dropbox.com/s/s5sj9sdb8g...10865.JPG?dl=0

Tap water. Got close to my neighbour's expensive Omega :-
https://www.dropbox.com/s/ybdcff5a7f...10875.JPG?dl=0

Boiling water. Bit short but close enough :-
https://www.dropbox.com/s/plb6p6x2n0...10877.JPG?dl=0

Both the Omega and my blue thermometers have dual input facilities and a
set-screw to tweak the temps +/-. The cheapo one doesn't have these options.
Over the last 5 years I've only used the dual input once (on the espresso
machine).

My blue one has an auto switch-off mode. The cheapo one does not. No problem
as I have loadsa re-chargable 9 volts.

I believe it's accurate enough - for the intended use. Change from £5 for
thermometer and s/s t/c probe is well worth the money IMO.