I can use the same configuration to operate the actuator from the output pins of an Arduino Uno with no problem so I don't think the problem lies with the actuator or mosfet circuit

Looks like the problem is some kind of interference affecting the receiver. The receiver module is designed for 5 volts DC I would not exceed that.
SG

 

Thanks for the explanation of VT
Yes I measured 0.5A while the actuator was activated. It might possibly be higher for a brief instant which my DMM can't catch.
My experience shows me that 5V IS sufficient to switch the mosfet and the actuator on. This is consistent with LesJones's reading of the datasheet. I have made probably 20 of these, using this exact mosfet and actuator, but I was using a previous iteration of the receiver modules which are now not available and which did not present this problem. I am having difficulties with the newer receiver modules for some reason. (It is probably not relevant, but they use a different frequency - 315MHz as against 433MHz). (Also, 5V from a UNO switches the mosfet and actuator on just fine.)
Yes, some of the modules require 12V. Even with the one I am using, the transmitter requires a 12V battery. But the receiver operates fine with 5V and so have all the other ones I've used. I don't know how to check the spec any further than what's on the ebay listing.
Yes, I have an antenna - just a bit of wire about 9 inches long.

 

I wrongly assumed it was an actuator that uses a threaded rod driven by a motor. (I have only just looked at the link to your actuator.) I will have to try to find out how they work to understand if they are likely to generate interference of any kind.

Les.

There is not much data on them available. Migamotors don't make them, they just bought up a stock. Essentially they are just lengths of flexinol-type wire which contracts and then some mechanics which translates the linear contraction into rotary motion; and a spring which pulls the wire back to the original length when current is removed. I thought that there was an internal switch which cut the current when the full rotation was achieved, but there must be a little more to it than this, because there the inputs have a polarity so there must be some real electronics inside too.

 

(It is probably not relevant, but they use a different frequency - 315MHz as against 433MHz).

Interesting. You may be on to something. I would compare the boards to see if there are some additional components on the 433 board that might provide decoupling or filtering. Just a thought.
SG

 

My experience shows me that 5V IS sufficient to switch the mosfet and the actuator on. This is consistent with LesJones's reading of the datasheet. I have made probably 20 of these, using this exact mosfet and actuator, but

Ok, your experience says this will work. BUT IT DOESN’T. You believe LesJones thinks it might work. But shortbus and I have stated that it won’t work.

I guess we’ll have to let the circuit decide. Oh wait, it doesn’t work!

Reminds me of an old IT story that was presented in a college class. True story (Well, the report times are best as I can remember. )

A team was assigned to create a parts list report for custom automobile assembly. After weeks of making no progress, our hero asked his boss to return home, convinced he was wasting his time He was allowed to leave.

On a long flight home, he had an ah-hah moment. He called his boss as soon as he got off the plane and described his solution. He returned on the next flight.

It was arranged for him to present his algorithm to the team. When he was done, the team leader stood and asked him how long it took to prepare the list for each car.

He replied, “Five minutes.”

The team leader laughed and said, “Our program takes ten seconds.” The remainder of the team joined his laughter.

Our hero replied,”But,but... Your parts list produces a car with seven tires and three steering wheels!”

The rest of the team would have nothing to do with his solution. Our hero returned home, the team was disbanded and several months later, the report was bought from a consultant.

I feel for you. It should work. It’s worked before. BUT YOUR CAR HAS SEVEN TIRES AND THREE STEERING WHEELS!