Microwave Modules MML 144/100 1/4
By alecjw on Saturday 27 October 2012, 22:01 - Permalink
I've done a little bit of digging around and haven't been able to find out much about this specific model. It seems to be a rare early version of this. The reviews I've found seem to indicate that my version is by far the preferred one, since the newer one catches fire when running at high duty cycle, as you might guess from the smaller heatsink.
When I got it, the power cord went in through a hole in the back straight onto the PCB with no grommet or strain relief. (No pictures, sorry.) I didn't like that so I desoldered it, drilled out the hole to 12mm and added a strain relief. It could perhaps have done with being a little bit bigger, since the heavy gague wires were a nightmare to fit through it, but I managed in the end. Here you can see my results: You'll also notice here that the input and output connectors are BNC and N-type respectively. The datasheet for the new model says that both should be SO259. I wonder if these were replaced by the last owner (G8UBJ) or if this was part of the original design? If it is a modification, I must say it's been done very professionally.
Here's a shot of the inside. You can see where the previous owner replaced a capacitor, which by the looks of the burnt remains on the PCB must have failed quite catastrophically. Theres also a 470pf cap I replaced by myself because i was clumsy and managed to shatter the old one.
It looks quite well built to me, and I expect it will last a good few years to come. I've tested it with a 10W rig and it seems to put out something in the order of 100W, although I don't have the equipment to make precise power measurements. One thing I don't like is the case being held together with self-tappers. Some of the threads are already knackered. Once my reprap's working I plan to print out some enclosures for M3 nuts so I can bolt it together, unless anyone can suggest more eloquant solutions.