AE9RB build notes

[AE9RB]

First of all, this is a good project overall. I sell amateur radio kits so I took notes during the build as if this was one of mine. Since I'm experienced at looking for minor faults it may seem like I'm bashing your project, but I really did think it was good. You asked for feedback, so here goes, without any sugar coating...

There wasn't any thermal relief anywhere on either of the PCBs. I had to turn up my iron to 700F and it still took 10-20 seconds for these pads to flow. Maybe you wanted this on the coil board but there's no reason for leaving them off the interrupter board.

The pads for most parts were too small for hand soldering. Combined with the lack of thermal relief makes for some very difficult soldering.

R10 and R11 did not appear to be 0.5W. They were the same size as the third 100k resistor. Looked like 0.25W resistors to me.

Resistor lead spacing is too tight. I bent the leads directly against the body and still had to force them into the PCB.

R6 is labeled 470 ohms on the PCB but the manual says 560 and I got a 560 with the kit.

Adding the color codes for each resistor inline with the construction steps is trivial. Maybe your goal is to "teach me color codes" in which case you need to add the divider colors to your table at the beginning so the 6.8 ohm resistor can be decoded.

The silicone pads were a bit too wide. It would be possible for someone to install them in such a way that the overlap got under the adjacent IGBT.

The main heatsink flops around due to only being supported by the IGBT leads. I can feel it wobble every time I pick up the chassis.

Some rubber feet for the coil chassis would be nice. Screw heads will damage tabletops.

Hardware measurements were missing for most of the manual.

The regulator for the interrupter was sealed up with a 4-40 nut and metric screw. One is obviously incorrect but not sure which because the manual didn't say. I used a 1/2" 4-40 screw from my parts box and all is well.

The main coil hardware seemed to be missing a 1/2" 4-40 screw. I only got two but you also need a third for the optical receiver. I had a 1/4" metric screw left over at the end.

The ribbon cable for the interrupter switches and pots was a bit too short. It didn't quite make it to the MIDI toggle switch. The MIDI switch is also too close to the power jack.

Did I miss a build step or is the metal-cased battery really supposed bounce around the bottom of the interrupter board? I stuck some rubber pad on the battery just to be safe.

The power pot seems to work backwards from what normal people expect. In the manual you have "Sweep the power knob from minimum to maximum while playing a note. Does the green LED fade and brighten correspondingly?" So no, it didn't, but I found a post on the forums saying you meant it to be backwards, so maybe it did.

There seems to be a lack of schematic documentation or I couldn't find it. I found a coil schematic on the web site but it had no annotations. I could not find a schematic for the MIDI interrupter.

Everything tests out so far except MIDI. The included MIDI adapter didn't work under OSX even though it said it would. It worked under Windows with my synth but not the interrupter. My two keyboards and guitar did not work with the interrupter.

I have an E-MU MIDI adapter here that somewhat worked with the interrupter but it didn't seem to play all notes and after a short while the optical transmitter stuck on. I was testing the interrupter on its own without the coil so I doubt ESD/RFI was the cause as is mentioned in the manual. Looked like a software problem.

Alas, I have no interrupter schematic and will need to purchase an ISP device. So debugging the MIDI problem is not going to be trivial.

My secondary arrived damaged. It appears to have been stuck twice by a pointed object. One of the strikes severed the wire. The bubble wrap has a hole in the same location so this apparently happened after the wrap was in place.

Everything is built and tested except the secondary and toroid. It looks fine for running in "fixed" mode. I ordered an inner tube and foil tape so I don't have to wait for the stamped toroid.

73 David http://AE9RB.com/

[Heidi]

Thanks for the detailed comments. It's posts like this that make oneTesla better!

[MikeNZ]

Hi David,

You've saved me a lot of typing - I just wish I had read your notes before I started. I heard my toroid was shipping so I figured I'd put my kit togther today, I had made many of the same notes as you.

Had to have my iron up quite high too. My R10 and R11 also appear 1/4 watt, I'm getting some 1/2 watt ones in the morning. I had the same R6 difference, after checking the schematic and seeing it was just the LED current limiting resister I stopped caring.

I had the same mismatched bolt/nut with my regulator. I seem to be short one 1/2" 4-40 screw too. But since I'm in metric world I'll be replacing everying with metric bolts for my sanity and making sure all the imperial ones go in the trash.

But everything went together well and all the low voltage tests are good. Once my toroid arrives I'll be able to fire it up

- Mike