Re: #pa #u3s Extreme power curve across the bands. #u3s #pa

SkipF, NT1G <skip.flem@...>
 

I'll bet my 'ticket', your backwards coil is FINE. Leave it for last.
Transformers for phasing are a different issue.
Extra winding (and too few) can be repaired without unwinding.
Don't make extra work for yourself.
73 es gud luck!
SkipF, NT1G

On Sun, May 26, 2019, 7:45 PM <nik@...> wrote:
Just spent the last few hours scrutinising the low pass filters.  Found a couple of mistakes.  One choke with a winding too many, and another wound backwards(!).... 

I rebuilt the 20m unit just to be sure.  The results are the same.

If I select the 17m filter and transmit on 20m, the result is as expected, an increase of around 300mW, and approaching 1W through the 15m filter.

I then made a bypass filter and tried that on a dummy load.  That was around 2W.

I guess the filter is doing it's job well.  Although the output on the fundamental is still very low at 200mW through the 5W amplifier.  I'm now thinking of experimenting with something compatible with the BC170, but with a wider frequency range.  Something like a BC184.

Join QRPLabs@groups.io to automatically receive all group messages.