Re: ubitx - stop press

Ashhar Farhan

One could push it that high, but not on the same PCB as the rest of the circuitry. I would say that 30 watts should be the tops. the RF ground loops on the board can make the entire TX chain wobbly. that said, i haven't tried anything of the sort. I'm curious to know what happens, i havent transmitted more than 25 watts for two decades.

- f

On Mon, Dec 11, 2017 at 12:16 PM, Jerry Gaffke via Groups.Io <jgaffke@...> wrote: write-up also mentions that power out is 10 Watts up to 10mhz, falls off to 2 Watts at 30mhz.
It is tough to drive IRF510's at 30mhz, but the WA2EBY amplifier uses two IRF510's in push-pull
like this to give 40 Watts up through 30mhz from a 28v supply.  Perhaps we can borrow some of the
WA2EBY design to approach that kind of performance.  May require beefier caps and coils.
And maybe an additional driver stage.

Also in the hfsignals uBitx write-up:  "TIA".
Not found in most dictionaries.
Means "Termination Insensitive Amplifier"

Jerry, KE7ER

On Sun, Dec 10, 2017 at 10:18 pm, AndyH wrote:
Just the close the circle, so to speak.  Farhan has additional comments in the sales write-up for the µBITX:
The power chain uses four common plastic 2N3904s in push-pull as drivers. The 2N3904s have enough gain at 30 MHz. The 2N2219s tried  earlier were found to have low gain at higher frequencies.

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