The switched LPF on the output should be sufficient. Allison ------------------------------- Please reply on list so we can share. No direct email, it goes to bit bucket due address harvesting in grou

#pa #wspr

A laptop PSU is a great home option! I do a lot of portable operation, so I built an appropriately rated, quiet DC-DC converter with sufficient filtering from a 12-13vdc battery source instead of modi

#pa

OK Nick, glad it worked for you. I like the KISS ethos. Never been very keen on Germanium diodes though, when they get warm they stop working ;-) You can get Schottky diodes that have a lower voltage

#pa #u3s

No. It would complicate the construction and make it harder to assemble. That is a alternate technique for getting the input and output further apart. and works well for dead bug assembly if space is

#pa

In the instructions for connecting the U3S to the 5W PA, C5 is removed to break the circuit to allow the RF to be routed out to the 5W PA and back into the Band Pass Filter circuit and then out throug

#mods #pa #u3s

Hi Hans, apologies, wrong terminology. What I meant was the output across the HF bands is very consistent, although at 20M there is a big dip, but I have a lack of drive at that frequency. It can't be

#pa

Hi Thomas The output of the Si5351A direct is likely a little weak to drive the 10W Linear to full power 10W output. I'd suggest keeping the U3S PA and adjust the U3S bias pot (R5) for around 25mW +/-

#u3s #pa

Alan: Back Home. QRP Quarterly Fall 2014, Volume 55 Number 4. I assume since they published it, it is copyrighted. Not sure if the raw article is OK to send? 73 Fred WD9HNJ

#pa #u3s

Another data point: Supply: 13.3V Receive current: 2.3mA /TX grounded (before adjustment): 63.4mA /TX grounded (after): 313.3mA cln - Nick WB5BKL Lake Buchanan, TX

#pa

Would you be able to take some pictures of your coil windings for those of us who are about to start assembling a qcx20?

#qcx #mods #pa

Robin, It has been suggested that the BS170s may well be destroyed by the high voltage produced by class E when not loaded correctly. It would seem possible that the destruction results in one of the

#pa #wspr #qcx

Bingo -- I swapped out the PA fets and the driver and all is working again. Wattmeter shows a full gallon. Thanks for the help everyone. James - AB9LM

#qcx #pa

Thank you very much for your detailed answers. I will think about that. Stefan

#u3s #gps #pa

Allison, yes it’s a pretty good fit. The book by EI9GQ and is titled "building a transceiver" and was printed in 2014 & 2015. ISBN: 9781 9101 9301 3 pdf Copy of the Sch is attached here. Drawn by me.

#pa #qsx

Al, That's the downside of the digital age. So many options, so many settings. Another "fault" cured:-) 73 Alan G4ZFQ

#qcx #pa

I pulled out the second one I built and with a wideband block amp (.1 to 100mhz flat, Pmax 25dbm) I setup to test. Line up is tracking generator out -> 3db attenuator -> Block amp +32DB -> Amp (qrplab

#pa #qsx