Some glass encapsulated thermistors I salvaged from some scrap telephone
equipment - I was hoping were RA53 as sometimes used to stabilise the
amplitude of simple AG signal generators.

Having found the data sheet online, I find that the RA53 has a room temp
res' of 5k - the one's I have are nearer 200k, so they might be RA25.

Anyone know where to look for info that might help in re designing such
circuits to accommodate the higher resistance thermistor?

TIA.