State of the ZM-100
Posted on August 25th, 2010 by Scott Gregson
As it says on our web site Emtech the development of the ZM-100 is stalled. It also says “Want to Help?”
Some folks emailed me inquiring as to what help we needed.
Here is a list of the issues I wanted to solve before we went into regular production:
- Front mount issue
- SWR Circuit
- Clearance on air-variable capacitor
- Needed to build a small injection mold for the front indicator pointers
- Solid mount for T1
- - wanted to have a mount method that did not require soldering/unsoldering any components to get inside enclosure
- - ? to use a powered circuit
- ? source micro-ammeters if for non-powered design
- ? PIC based SWR/Forward circuit
Please post if you have ideas, interest in moving this project forward.
Did you look at a more simple enclosure? Radio Shack sells a 7x3x5 enclosure. I have started building my 100W Z-Match and this is the enclosure that I have selected. The tuning capacitor is exactly the same as the one you are using and probably came from the same source. With anything less than 3″ of height I ran into the same problem. Some of the obstacles I overcame using the all plastic case is the need to isolate the main tuning capacitor! There are many designs for swr circuits out there. Why did you feel the need to isolate the coil from the rest of the circuit? I used a larger more robust T200 coil in mine but the coil that you are using is probably large enough I wish I had used a bit smaller one it is huge but I am not worried about power one bit! I saw a posting about making a kilowatt z-match that Zach Lau chimed in on that said you could get a kilowatt out of 2 of the toriods stacked if Zach says so it is true I would bank on it. I wouldn’t worry too much about the toroid being too small. I think keeping it simple, inexpensive and let the community work out he bugs will do you just fine. I will send you a picture when I have finished mine maybe it will give you some ideas?
Mike
Answers:
• When I did this I searched and found the enclosure I liked. It has good weight (doesn’t move around when tuning), I think has a great look, and hopefully the compactness wouldn’t cause issues with performance.
• I was not trying to isolate T1 – I was the only space left and I needed to mount the band switch ans SWR board. The plate provided that mount.
• The T1 torroid – cost isn’t the issue – torroids are cheap.
• One thing that I need done is to fry 1 or two units. We need to actually find where the breaking point is. The air variable caps are rated higher than the 100 watts. We need to know what 100% load is so the tuner can be rated to work at 80% of that. I don’t have the antennas or equip. to force it into arcing, overheating etc.