Well after loads of messing around I eventually bought all new gear. So I now have a 160 Amp ESC, brushless motor and LiPo batteries. The 48" Perkasa runs like a dream. Not sure if the hyper link works. Noise from out of balance prop but sorted now.

Thanks Dave. I will keep you posted.

From your figures the pulse control range is far short of the 1ms width I would expect to see (0.5ms either side of neutral). A solution would be to use the EPA on a digital transmitter to restrict the pulse width.
When I think about using an Mtronik15 I believe I did have to adjust my settings to stop the motor cutting out on full stick movement. Sorry to have not mentioned this before, but I sail yachts as well as electric powered and am used to adjusting the transmitter to suit servo throws etc so its almost second nature and nothing out of the ordinary.
I suspect the chips they use are all from the same source and the code has been changed so affects all ESC's regardless of their provenance.
Interesting web site you mention, had a quick look and reminds me of my home made speed controllers from the 1960's. Hope you find a solution and manage to power your model successfully. 😀

Hi. I have tried an Acoms 27Mhz RC and a 2.4Ghz RC both do the same thing. I have given up with Mtronik. it looks like they have buried their head in the sand maybe because they do not know. So moving forward I am going to build my own speed controller based on an article on www.pt.boat.com.

For what it's worth this is what I sent to Mtronik:

"Sorry but this made things worse on both Viper ESC the 25A and 40A have the same problem so does my cheep Chinese Import.
I have set them up on my bench now with the digital scope coupled up to confirm what is happening and have come to the conclusion there is something in the software causing the problem. This is my test method. Two 6 Volt gel batteries coupled in series feed the main power to the ESC. A separate 6 volt supply powers the servo tester. A 4 Watt 12 Volt bulb is connected to the ESC output (this is to give load and make sure there is no EMC) The servo tester is giving out 0.945 to 1.926ms with centre off around 1.452ms. At 1.087 and 1.85ms the ESC's output switches hard off and on. This is what causes the flickering on the bulb. All that happens when I use the left or right mid point to set the travel is the problem moves in proportion. Which makes me think it is a software glitch. Would it be possible for you to set this up and replicate it?"

Interesting. Clearly some sort of timing issue. What RC set are you using? Their solution suggests the ESC is not able to cover the whole of the pulse width. As a matter of interest does the same fault happen in reverse?
I look forward to hearing how you progress.

Just to let you know I have received this reply from Mtroniks and it made matters worse.

"Have you tried reducing the throttle end pints on your transmitter? This would bring the throttle end points closer together and stop the controller from seeing the spurious signal at 75-80%. Dong this would not effect your feel or proportionality in any way.

Let me know how you get on.

Best regards,"

I have replied to them with the outcome and await their reply. 😀

Thanks for response Dave. I did some more checks yesterday (Sunday) and ran the ESC from a servo checker. I put a 4 watt 12 V bulb on the output of the ESC. Coupled it to my digital scope and sure enough the wave form is very clean but switches off and on at around 75% throttle. The PWM looks like 1Khz so it makes the bulb flicker rather than switch off and on. As soon as the throttle gets to 90% it clears up and at 100% full voltage is applied. I did this on all three ESC and the result is the same. I have written to Mtronik as my conclusion is the ESC cannot resolve the change in mark space well enough. it looks like the system thinks there is a loss of signal so it shuts off. From what I can gather most ESC use the same embedded software in the PIC.

Just as a matter on interest I did all the usual suppression things including running a large separate negative wire to the RX.

Will post what Mtroniks have to say to the site if I get a reply.

Looking at the spec for the MFA 850 Torpedo the max current is quoted at 10.2 amps at 12v. Assuming you are using the two 6v batteries in series giving 12v then the ESC should be OK.
Do you know the actual amps being drawn by your motor? Could be the prop is two big for the motor. IC props are usually too coarse a pitch for electric motors. if you can borrow a wattmeter you can check this at the bank with the prop in the water.
I would check that the prop shaft and motor are aligned and that there is no stiffness in the propshaft. This is a common cause of heavy current.
Brushed motors are good at generating electrical noise which will play havoc with your electronics. You need to fit suppressor capacitors: One across the motor terminals and another two from the motor case to each terminal. I use 0.1uF ceramic. The placing of the wiring in the boat should be such that the high current (dirty) wiring is as far away as possible from the signal wiring and aerial.
The fact that your problem starts at high power throttle suggests sparking interference is causing the problem. The 2.4 Ghz will not be too affected but the ESC will be.
Do make sure that your aerial is above the waterline in the model as 2.4Ghz will not pass through water.
Hope this helps solve the problem. 😀