RF receiver

I have this Rf transmitter & receiver which uses ASK modulation. A comparator is connected to the receiver. My problem is that the resistor in the comparator is unstable and as a result a potentiometer is needed in order to receive the signal coming out of the transmitter. Does anybody has a solution for this? I don't want to use a potentiometer in order to receive the signal coming out of the transmitter. I need a stable resistance.

"...the resistor in the comparator is unstable and as a result a potentiometer is needed in order to receive the signal coming out of the transmitter without varying the potentiometer..." !?
Sorry, can you translate?

Sounds like an inappropriate threshold circuit in ASK demodulation. You may want to study existing ASK application circuits, how they handle it.

Problem is not clear.
May I ask you to frame simple and large number of sentences?
Can you share the schematic and explain why it is unstable?

I have this Rf transmitter & receiver which uses ASK modulation. A comparator is connected to the receiver. My problem is that the resistor in the comparator is unstable and as a result a potentiometer is needed in order to receive the signal coming out of the transmitter. Does anybody has a solution for this? I don't want to use a potentiometer in order to receive the signal coming out of the transmitter. I need a stable resistance.

EDITED

Unstable resistor? Unstable with what? With temperature, with current, with humidity, with light?

I believe it unstable with frequency.

So, at different frequencies has different resistance values?
For a standard resistor this is valid only at microwave frequencies, which is not your case.

I'm not quite sure about this, but I'm using only a fixed frequency. But for me to receive clearly the transmitted frequency, i have to vary the potentiometer.