hi
am a beginner roaster i have huky500t
there is something strange , first when am preheating my roaster the (ET) temp increase so fast that the (BT) temp is 74 and the (ET) temp is 150 and am preheating with just 1kpa
and when i drop the beans the (ET) not going down it start increasing the moment i charge the beans
i attached img of what is happening to me

what should i do to fix this ?
thanks alot every one

I am guessing the initial differential is due to where the probes are located. I am guessing the increase after dropping is because the air flow is being sufficiently restricted to cause the temps to rise. Maybe someone else knows better. You could try physically swapping the probes and see if achieve same results.

Well, the Huky forum seems like it's down at the moment.

First, about preheating. I usually allow the roaster to preheat for at least 15 minutes (so that the exhaust etc. is at working temperature too). Nice and slow at around 1-1-5 kPa. You are doing the right thing, but you need to let the roaster run for some 10 minutes more once you are up at say 200C BT (and keep it at 200C with a bit less heat and some airflow). (You don't say if and how you control the airflow, but if you only use the damper, put the fan on with the damper closed or almost fully closed, else with a fan controller just a slow fan will do.)
The idea with preheating is that the 2 readings,BT and MET (and ET too), to be steady and very close together over a period of time.

Second. The "ET" that you have is from the very top of the roaster, outside the drum. It's named "MET". You don't say if you have an analogue ET meter (5 cm dial on the right side of the center of the drum), but I guess that is the case.
If you want to record and show the ET curve in Artisan, I'd recommend that you get a digital ET replacement probe from Mr. Li. It's only about $20 or so and he sends it in an envelope the same or next day after recieving payment. (Replacing it is very easy, you just need to undo the analogue meter (with a 14mm spanner) and put in the digital one and hook it up to you thermometer or phidget...)

About the roast. It looks like a very good roast. The values from your MET looks very normal and indicates that you have a solid drum setup.

thanks all for the reply
edtbjon, i thought that the top thermometer was also (ET) thanks for the information, is it necessary to have (ET)? and about the roast it looks good by looking at the curve but the problem is that the roasted coffee beans are really burned i tried charging with 180c and 195c and the gas is started after 1 min by applying 1,8 kpa and drop the beans when reached 210c
(12-14 min) roasting time