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QRP-Labs 50W amplifier 

This page was last updated : 17-Dec-20 11:49:36

When I met QRP-Labs founder and designer Hans Summers G0UPL on the Dag Voor De Radio Amateur 2019 (DVDRA 2019) he showed me a prototype of his new kit a 50 W amplifier specialty designed for his famous QCX. The simple and compact design appield to me, so when it came out early December 2019 I ordered it. 

Not expecting someone ringing my doorbell on the last Saturday evening of December 2019 but the parcel service dropped of a package. It is the 50W amplifier for my QCX.

After sorting everything out it was time  to do some soldering.

The problem with the great qrp-labs kits is that they are to much fun to leave on the workbench. So the next day it was already build and tested. 
But I still made some pictures during the building progress.

During the build I found some minor errors in the supplied documentations. The findings I have post on the QRP-Labs groups.io page. 

it seems that there is a difference in the PCB silkscreen drawing  in the documentation and the silkscreen on the actual PCB.

Topic 3.8 Install Low Pass Filter capacitors C14 and C18

- C18 in documentation is C19 on PCB
- C21 in documentation is C22 on PCB

3.10 Install Low Pass Filter capacitors C19 and C20 (30m only)

- C19 in documentation is C20 on PCB
- C20 in documentation is C21 on PCB

It's not a big deal but worth noting.

Edit 3 Jan 2019 : Hans has updated the manual on his website. 

When you have the optional QRP Labs enclosure, in the topic 3.31..3.33 it states that you have to take care of the aligment of the holes.

I found out that the easiest way is to screwed in the RF in and Out in the backplate loosely place them in the PCB. install the PTT chasis part, screw the nuts on the RF in and Out tight and place the DC powerin chasis part. Align the last one with a DC plug and now  everything is alligned and ready to get solderd (start with he RF In and Out chassis parts as desribed in 3.33).

It then will fit without problems. 

You might note that I didn't completly follow the documentations. For example i started with the lower components instead of winding the coils (the coils are much higher then the lower components)

After winding the coils, checking, and again, checking, all the components. it was time for alignment. 

I have set it up on 12V and adjusted it according to the manual (full counter clock wise  85.3mA and adjusted it until it raised a bit above that and then back to the 85.3mA). Switched my QCX out of practice mode and got a nice 20W on my old power meter (don't know if it still accurate).

After the test, it was time to box it all up. 

 

 I only can say : QRP-Labs founder and designer Hans Summers G0UPL again did it. A very nice and effortable hamradio kit. Can't wait to test it in the field. 

 

 

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