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
Hi Paul - Im running Jays design for the 1Kw version but with only 2 FETS in the final issues for me were secondary and primary winding on output were physically too loose and gave rise to too much l
Paul Maybe try some 14 or 16 gauge lamp cord ... it's pretty pliable and can be wound tight against the core. That's what I used in the 500 watt deck. Put a piece of wet paper towel around the insula
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
Hello Paul These are what I used, cheaper from Bulgaria, or Russia: https://www.ebay.co.uk/itm/Silver-Mica-Capacitor-Glass-Silvered-Mica-Military-Cap-Various-Values/120797139825?hash=item1c20121371:m
Paul Okay on 78 material. Wonder if you measured your snubber caps? Notice they're maroon color which would indicate they're old ... possibly used or an off brand? All new CDE mica caps have been yel
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
Paul Sangamo is a good brand ... so if they're NOS, and the correct value, the problem probably lies elsewhere. Is your secondary winding solid or stranded wire? I find solid #14 THHN better conforms
Hello Paul, the audiofool speaker wire I used is very pliable even at room temp. I tried it as it's a twin (bonded) flex, so no need for an outer sleeve to bond the two tight together. I found a shri
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
Paul Roger all. Now that you mentioned the scope probes ... to get an accurate view of the waveform I remove the long scope probe 'hook tip' and use just the remaining short pin as the probe. I also
Paul Here are some gate pix with Vdd off (Vdd supply not handy at the moment). www.w1vd.com/FETgate1.jpg www.w1vd.com/FETgate1.jpg Sorry pix quality isn't better. Notice dead zone between the two pha
Paul The 1000 pF caps I used are mylar ... suitable for timing applications. Ceramic caps, if that's what you're using (sounds like it might be since they're Kemet), have rather poor value tolerance,
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
Hello Paul, effectively the same as I am using, so I think you can safely discount those. Have you tried de-coupling caps yet, especially on the driver IC? I think the hump on the gate waveform is th
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 Paul, about testing without drain voltage: Be aware that the input (gate) capacitance will be a lot larger at 0V Uds. This might affect the waveform at the gate! 73, Rik ON7YD - OR7T Chris, I thin
Hello Paul, Yes, I put de-coupling caps on all of those, although some are tied together, I went for over kill! Can you temporarily jury rig the driver board right by the FET's and then try shorter g
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
