Hello Paul I can understand what kind of ampliifcaotre you are
indifficulty I read with pleasure the work you are doing but I do not
understand what kind of scheme you are using you can publish the
scheme thanks Google translator sorry
73 Antonio ik1hgi
Ciao Paul posso capire che tipo di ampliifcaotre sei indifficoltà leggo
con piacere il lavoro che stai realizzamdo ma non capisco che tipo di
schema stai usando puoi publicare lo schema grazie traduttore Google scusa
73 Antonio ik1hgi
2018-04-22 19:23 GMT+02:00 N1BUG <[email protected]>:
> For sake of completeness, as there were some following this hoping
> to learn from my experience...
>
> After a break I went back to work on the amp.
>
> I swapped out the IR2110. No significant change.
>
> I swapped out the 74F74. No significant change.
>
> I replaced all four 1N4148 diodes on the gates with diodes from a
> different lot/source. No change.
>
> I experimented with the resistors on the gates, from 4.7 ohms to 47
> ohms. Lower value resistors make the cross conduction problem and
> drain ringing worse. Higher value resistors do the opposite but with
> some penalty on power output.
>
> I swapped out all four FETs. This returned drain circuit ringing on
> both sides to equal (as it had been originally) but did not fix the
> problem.
>
> I built two more versions of the driver board, same circuit but
> different physical construction. This definitely makes a difference
> in gate rise/fall times, cross conduction and ringing but none of my
> variations made it good enough. In fact the first version was the best.
>
> I tried moving the driver board around, mounting it closer to and
> farther from the FETs with varying gate twisted pair lead lengths.
> This made a difference but seemingly not in any predictable way.
>
> I believe there is some issue with my particular build wherein for
> whatever reason the driver cannot turn the FETs on and off quickly
> enough. It definitely appears the slow gate rise and fall times are
> causing or at least worsening my problems.
>
> Jay's design does work. I hear several of them on the air every
> night and they are reliable. For whatever reason my particular build
> does not work. Please don't judge a book by its reader. :-)
>
> I wish to commend Jay on his tireless assistance in the effort to
> figure this out.
>
> In the end I feel I am not learning anything from this and I have
> decided to move on to other things. I am also looking forward to a
> summer break from building.
>
>
>
> Since I am considering an upscaled version of my current class E
> amplifier, I put that back on the bench and was taking some
> measurements. It uses a single 34N20 FET. In particular I looked at
> the gate waveform with the same scope, probes, and settings I've
> been using with the W1VD deck. I was shocked at how steep the rise
> and fall times are and how it seems to 'power through' the FET
> turn-on anomaly. This stands in stark contrast to the W1VD deck with
> its slow gate rise/fall and long hiccup at FET turn on. At least I
> know the scope is capable of displaying a 'crisp' gate waveform. ;-)
>
> Paul N1BUG
>
>
>
>
--
Salve Antonio ik1hgi
http://www.qsl.net/ik1hgi/472khz/gps-x.htm
http://www.qsl.net/ik1hgi/472-50.htm
http://www.qsl.net/ik1hgi/qrp/index.htm
http://www.qsl.net/ik1hgi/eqsl.html
[email protected]
[email protected]
Antonio ik1hgi 73
RISERVATEZZA (ai sensi D.Lgs n. 196/03)
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