Re: Using IRF530 outputs and 2N3553 drivers in ubitx
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At the level of 100 watts, it makes immense sense to just go with MRF150 or one of the higher end mistuibishi devices. The IRF series are very prone to oscillations. They are gratifyingly well behaved on the bench with a dummy load. They go wild with the antenna. My favourite configuration for more than 100 watts is actually a bit of steam-punk. You can pick two 6146Bs for 10 dollars off a good online supplier. I bought several from last year's Dayton schelp. A valve amplifier will be very forgiving with SWRs, it has a sparkling SWR, it uses air wound coils. Surely, the power supply is a big of a challenge, but not really. The audio aficiondos have rejuventated the supply of high voltage transformers. A great linear amplifier with two 6146Bs will serve you and your kids for a long long time. I am going to rebuild my double-807 job to these tubes soon.
- f??
On Sat, May 19, 2018 at 8:53 PM, Howard Fidel <sonic1@...> wrote: After I wrote the last email, I realized the cascode configuration is much better.
It needs 2 more FETs but you drive the gate of the first one, and it provides the drive to the second one and the second one's gate is AC ground. I can't do it now, but I will see if I can find time to design one next week.
If you wanted to do this with uBitx, remove the exiting output xformer, add 2? IRF530 and a higher voltage supply, with a new output transformer. Should get up to 50W easily without changing the driver.
Howard
Quoting "Rahul Srivastava via Groups.Io" <vu3wjm=[email protected]>:
Thanks..!!? Alison for the detailed analysis. Just to scratch the itch maybe I will hook up one in mid air with a 25:1 transformer at input and standard bifilar on drain.?
I once made 3x3 pushpull on IRF510 running at 30V for? 27.120Mhz ISM band freq got pretty decent 150W output. Input was on binocular core and output on stacked Mix 6 toroids.?
73
Rahul VU3WJM
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