Set up temperature sensor m308

Hello, I have been struggling with the problem that my ntc 100k 3950 sensor shows the wrong temperature for three days now. I have a thermometer for calibration, and so, at a temperature of 25 degrees, the difference in the readings of the printer-thermometer is about 0.4 degrees, at 70-100 degrees - 10, at 200 and above degrees - already 20-40 degrees. Reprap 3.4 firmware, rrf e3 board,
my settings from config.g

; Heaters
M308 S0 P"bedtemp" Y"thermistor" T100000 B4092 ; configure sensor 0 as thermistor on pin bedtemp
M950 H0 C"bed" T0 ; create bed heater output on bed and map it to sensor 0
M307 H0 B0 S1.00 ; disable bang-bang mode for the bed heater and set PWM limit
M140 H0 ; map heated bed to heater 0
M143 H0 S120 ; set temperature limit for heater 0 to 120C
M143 H0 S120 ; set temperature limit for heater 0 to 120C
M308 S1 P"e0temp" Y"thermistor" T100000 B4072 C1.375060139e-7 ; configure sensor 1 as thermistor on pin e0temp
M950 H1 C"e0heat" T1 ; create nozzle heater output on e0heat and map it to sensor 1
M307 H1 B0 S1.00 ; disable bang-bang mode for heater and set PWM limit
M143 H1 S350

As you are talking about temperatures of 200C I presume it is the hot end sensor thay you are referring to. How are you measuring the temperature of the hot end? If you are using an infrared thermometer, it won't give you an accurate reading because the target area is too small, so it will read lower than actual. You can get a more accurate reading by feeding a thermocouple into the hot end through the filament tube.

If you can get accurate readings at three temperatures, you can use the SRS calculator or the calculator in the RRF configuration tool to calculate the B and C values for that thermistor.

You may also wish to post this question in the STM section at [forum.duet3d.com].

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

I use a thermometer "rgk ct-11" for measurements, it is a contact, type k thermocouple, I attach it to the block with a metal clothespin.