It sounds like the UL3S is best suited for weak signal digital modes like WSPR and that the QCX- mini would be better suited for a CW beacon and the QCX has some other amazing attributes like CAT control which opens up the possibility of remote control which is beneficial since my 10m beacon is over 100 miles from my home QTH. ?I¡¯ve experimented with the CAT and it works very well. ?I have a QCX mini that I built then accidentally destroyed the CPU out of shear clumsiness but I went ahead and ordered a replacement today. ?I think it put out a solid 3 watts before I destroyed it. ?But I might also experiment with the UL3S to increase power output by adding a driver or an outboard amp. ?
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On Sep 22, 2023, at 2:14 PM, Shirley Dulcey KE1L <mark@...> wrote:
?
That's why other QRP Labs designs like the QCX and QDX have a driver stage. It's pretty simple, using some CMOS gates, but it's enough to drive the BS170 transistors. The U3S is a QRPp transmitter (under 1W) so it doesn't bother with the driver.
On Fri, Sep 22, 2023 at 1:45?PM Alan G4ZFQ <
alan4alan@...> wrote:
On 22/09/2023 17:38, John Z wrote:
>? ?I think the total capacitance may
> be too much for the chip to swing at 28 MHz.
I think the reason is that they are not driven hard enough just by the
Si5351. Maybe add a driver?
73 Alan GZFQ
