Jay, I appreciate your help with this. See below. Forget that rather poor picture. Here are better ones. Overall view #1: http://www.n1bug.com/vd-amp1.jpg Overall view #2: http://www.n1bug.com/vd-amp
Yep, voltage breakdown of the FETs was my worry. However I may be making a false assumption. I assumed the voltage spikes in the ringing would vary linearly with applied drain voltage? Perhaps that i
I had to use the (carefully resonated and matched) antenna for this test rather than a dummy load but it appears the maximum voltage spike in the ringing does indeed vary almost linearly with applied
Hello again Chris, Yes that's what it is and yes that may be a problem. However at the moment for testing and troubleshooting elsewhere, I'm not using that board. There are no wires whatsoever connec
Jay, Oops. I took a picture of the LPF this morning and uploaded it to the server. Then I forgot to include the link in my earlier reply to you. Here it is: http://www.n1bug.com/vd-lpf.jpg I used the
The core is 78 material. I tried again with different wire. The winding is somewhat tighter on the core but definitely not what I was hoping for. Clearly I am not bringing required skills to the tabl
Jay, I have no reliable way to measure capacitance. The ones I used originally were NOS Sangamo caps. The physical dimensions are the same as I find listed for DM19 caps. Last night I swapped one out
Jay, The secondary is #14 solid THHN. It is tight to the core only at the sharp bend areas, that is to say four places per turn at the "corners" of the core. This was the best of *many* attempts. Ini
OK, let's switch topics a bit. I have a serious drain circuit ringing problem that most builders apparently don't have. Many things change all but the first peak of the ringing, but that first one is
Andy, Jay, all The next thing you're probably going to tell me is to remember the flux density equation when designing such a thing. :-) I have yet to grasp how to work with that. To me it's a viciou
Aha! Jay See! Mine are *not* the same. In yours, one phase drops all the way down, there's a slight dead zone, then the other starts coming up. In mine, one is still on its way down when the other st
Jay, The caps I used are polyester. Here's the datasheet: https://www.mouser.com/datasheet/2/212/KEM_F3101_R82-1103738.pdf It mentions timing applications, but I am no capacitor expert! Comments appr
Chris, I think it was after looking at your driver board photos that I decided to order these particular caps. They look exactly like yours. ;-) I haven't tried the bypass caps yet. Given we're now t
Hi Rik, Of course that is true and I can see a difference in the gate waveform with Vdd on and off. But it doesn't explain why under same conditions (Vdd off) Jay and I see quite different gate wavef
Hi Rik, I don't recall that having been mentioned previously in this discussion. I am sure I have read that somewhere in my studies over the past year but it obviously had not taken root as it seemed
Jay, I agree everything points to a problem in the driver circuit. This morning I set up the scope very carefully, took pictures of the gate waveform with the 2000pf. I then removed the added cap on
Jay, When the package arrives I will swap out the caps and the IR2110. If that doesn't do it I will order a new 74F74 and swap out the resistors. If all of that fails I don't see anything else I can
Hi Chris, Actually that's a bit of trickery on my part. :-) I wanted all the coils to "look" about the same. All the Delrin end plates are 1/4" thick. On the center one I wrapped the core with glass
Today I verified board connections again, including power to the driver IC (tnx Luis). With the scope I checked +5v and +12v power at IC pins while operating to be sure it is clean. All looked OK. I
