Bat 41 Diodes Forward Voltage Drop- Tayda diodes etc

[claytushaywood]

I am trying to build a zen drive again (havent had one in years- and I was just thinking- damn that was a great OD) So I go to measure the forward voltage drop of the bat41's I have on hand- and they measure .22Vf- which seems pretty low.  So I googled and it looks like bat41's should be around .4Vf or so...? 

Can anyone tell me if these tayda bat41's are too low?  I know theyll work and possibly sound good, but i want a spot on zen.  Tayda has also sent me 1n914's that measure .3Vf and 1n34a's that measure .6Vf.  Some of them dont even look right- I have some red bat41's (look like 1n4148's) that measure .25 and some 1n4148's that look like 1n60's that measure something way low.

I did find some other bat41's in my stash that are measuring .35Vf.  are those good?  Thanks!!

[claytushaywood]

I just assumed the bat41's were clipping diodes- now I see there in the loop with the mosfets doin something- not sure what?  Does the Vf even matter with the bat41's?

[pickdropper]

The BAT41s I received from Tayda were out of spec; low even for BAT46s.

I've also purchased BAT41's from a known, reliable vendor (Allied Elec, I think) that looked like 1n4148 and they were fine.  They had the correct Fv.

I would use the ones in your stash that measure 0.35V.  Those should work fine.

[midwayfair]

The diodes in series with the MOSFETs prevent the MOSFETs from reverse conducting. MOSFETs conduct in two directions. See here.

[Side note on the Zen Drive: It's asymmetrical on one side by a single diode.35V (or whatever), which is about 1/5th the total Fv of the MOSFET + BAT41 on the other side, which is honestly kind of silly IMO ... can you hear a 20% difference in wave symmetry? In a tube or other triode it's usually 2:1, not 6:5.]

The Fv on diodes will vary based on the multimeter used. The only other reliable measurements besides personal experience are under the identical test conditions (e.g. current) found in the datasheets.

I sort diodes in a bin by approximate Fv as measured on my current multimeter. When I had to switch multimeters, I just measured one of the diodes already in the bin and put any new ones in whatever the match.