RV Repair: furnace wont light, furnace fan, wall thermostat

Question
have a 1974 scamper with hydroflame hf-16 furnace has a wall thermostat but doesnt seem to have any power source what opens the gas valve to allow it to light if i hold the knob down for a long time after lighting the pilot it sometimes stays lit but when i turn it on the main burner doesnt light what i would call the thermocoupler looks different than anything ive seen before about 7/16 in in diameter and made out of wire what is this i read a very vague article that said this creates the power to activate the gas valve is this true?

Answer
That furnace no longer has parts available for it, and the part your describing is called "pilot generator", not a t-couple.
I believe the way that works is, the pilot generator heats up, then that sends a signal to the furnace fan motor to "spool up" blowing air across the sail switch which opens the gas valve too obtain full burn. Then you get heat and forced air.
Thom