Hi Stefan,
Thank-you for the tip. The totem pole worked well for me (thanks
to Alan G3NYK) but the waveform was a bit mushy and I suspect it
may have contributed to the demise of many FETS as a result of
operator incompetence (High SWR, etc).
Could you provide more details on your class E for 1820 kHz? Are
key-clicks a problem on top band?
73
Joe
On Mon, 12 Nov 2012, Stefan Sch�fer wrote:
Hello Joe (VO1NA),
If you're doing modifications on your PA FETs, try the IXDD614CI
<https://dl.dropbox.com/u/19882028/Datenbl%C3%A4tter/IXDD%20414CI.pdf> MOSFET
driver. I can assure you that gate drive problems are gone then! I use a
single IXDD614CI to drive 4x IRFP260N (gates in parallel) in a 1820 kHz class
E PA without any problem :-)
73, Stefan/DK7FC
Am 12.11.2012 11:19, schrieb [email protected]:
GM Gary and Group,
Thank-you for the report. The TX was the original 100 watt unit (Jul '05
QST) somewhat modified. After frying many FETS over the past decade, a
4427 driver and IRFP260 hexfet was tried. It seems this FET had too much
gate capacitance for the totem pole driver, hence the 4427. The gate
waveform looks a lot better and the heatsink was cool this morning,
presumably
because the RDS was lower than that for the IRF640.
The Decca is on standby after a heart-breaking experience. More on that
later...
Thanks to you Gary and the others who operate the grabber services.
73
Joe VO1NA
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