The final stage of the build process involved final assemble and testing. The last few resistors, a zener diode and a trimmer pot were soldered in. Then it was time to wind and install toroidal inductors. The only tricky one was the transformer, which has two windings.
Next came inserting the metal standoffs onto the PCB.
With the standoffs in place, it is beginning to look like a radio.
Once that was done, it was time to scrape off the paint on the enclosure so that there is a good earth between it and the standoffs. I did this with a rotary tool.
Having the right tools makes the job easier. Sand paper will also do.
I then installed the red filter over the LED display opening, soldered in the final transistor and carried out some voltage checks to see if all was okay. I then attended to the installation and wiring of the internal battery holders. This was a little tricky but didn’t present any problems, except that I applied too much solder to one of the crimp terminals and so ruined it. A quick email to Elecraft resulted in two new ones being mailed out to me that same day. Awesome service.
The PCB in place mounted to the upper part of the enclosure.
Time now for final alignment and testing.
Testing the transmitter requires taking power readings on both bands with an accurate power meter; one that can read power at QRP levels. I have two; a QRPometer, and a Hendricks dummy load/power meter. I used both.
QRPometer on the left, Hendricks dummy load/power meter on the right.
This is what I read:
20m @ 13.8V: 3.8W
40m @ 13.8V: 2.66W
Hendricks dummy load/power meter
20m @ 13.8V: 3.5145W
40m @ 13.8V: 2.66W
The formula I used to calculate power with the Hendricks meter is as follows:
The instruction manual says that power on both bands should be between 3 and 4 Watts, so clearly my 40m readings are a bit low. I emailed Elecraft and was told the readings look typical, but I want a little more power, especially on 40m as Down Under it was come in handy. I was told to change the values of R11 and R30 to between 4.7 and 5.6 Ohms, and 27 to 33 Ohms respectively. That is the next thing I will attend to, when I can source such low value resistors.
The rig complete and ready for the first on air test.
Time for the first real test. I plugged in my Touchkeyer P3K and tuned around on 40m on 1 March 2013 and heard ZL1IG Robin calling. I answered and completed my first QSO with this rig. He gave me a 339, which I was pleased about, especially since the distance between us was 1,549 miles. He is in Invercargill and I am in Brisbane.
Two days later, I decided to try 20m and answered FK8CE Dominique, who was calling from New Caledonia, a distance of 891 miles away. He replied and we had a satisfying QSO. He gave me a 599. After that, I tuned around and heard HB9BQR Roland calling from Solothurn in Switzerland. I answered and he gave me a 579. That was fantastic because the distance between us was 10,133 miles. We had a long QSO, so it wasn’t just a case of luck.
The antenna I was using was a simple dipole up at around 15 feet.
Now to wait for the crimp connectors to arrive and then to source some resistors, and the rig will be complete. Perhaps I don’t really need that additional Watt of power!