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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 yellow in color for some time. Can't tell from the pix ... are they really DM19 size? The russian blue glass mica's that Chris mentioned (same as I used) are excellent. I've used these in applications where other 'lesser' mica's were pushed beyond their limits. Will check to see if I have a couple extra. Don't be in a hurry to start changing values since a number of these amps have been built 'to spec' with the no ringing problem. There's something in your amplifier / system thats causing the anomoly.
Did you try using a wider connection to ground on the snubber resistor? Grab some zip cord off a little used lamp ... it will be fine for 'low power' testing. It will wind tight aagainst the core.
Jay W1VD
----- Original Message -----
Sent: 4/9/2018 9:37:37 PM
Subject: Re: LF: W1VD amp help - more waveforms
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 table on constructing this.
Drain waveforms became somewhat asymmetrical with one phase having a
somewhat different shape from the other but peak voltage was
similar... 65V on one side, 63V on the other with 13VDC supply.
I'm sure this was a bad idea but out of curiosity I tried adding
another 500 pf in parallel with the 1500 pf snubber cap on one side
only. Power output and efficiency did not change but peak voltage on
that side dropped a couple of volts. I then increased that side to a
total of 3000 pf. Power output and efficiency has still not changed
at all but peak voltage on that side is down to 50V and it stops
ringing significantly sooner than the other side. Does this suggest
anything other than insanity of the builder?
Paul
On 04/09/2018 05:29 PM, [email protected] wrote:
> 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 insulation
> when soldering to prevent 'melt back'.
>
> Is your core 77 or 78 material?
>
> On your driver board ... are there reasonably wide traces ... especially from the 12 volt power
> supply to the IR2110? Peak currents can be high driving the gate C. Is the 12 volt supply reasonably
> stout?
>
> Jay W1VD
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