BUILDING THE QDX 'REV2' BOARD
I recently built the Original QRP-LABS QDX (Rev-1) and everything went very well. It was an enjoyable kit and so I thought I'd purchase the Rev.2 board so I could keep one in the shack and stick one in my 'go-bag'.
I'll state right now that this build did not go well initially - there were problems which drove me nuts and I later found out that it was nothing to do with anything that I'd done - it was a fault on the PCB.
I chose to record all the details of the build (and the struggle) so that anyone else who experiences similar problems may benefit. Bear in mind that this is written from the perspective of a BEGINNER with virtually no electronics knowledge. So here we go....
This updated kit thankfully didn't have any SMD parts to worry about and I found it extremely easy to build. If I say so myself, I did a great job of all the toroids and was especially proud of my L12 with its awkward taps. It was much neater than the first one I did.
It fitted onto the PCB like it was made to measure and I experienced no problems. Neither did I have any problems with the trifilar T2. I took my time with it and made doubly sure that I had the correct A-A, B-B and C-C. I even went to the trouble of colour-coding them with a touch of acrylic paints (my other hobby is painting) 😊
Before I loaded WSJT-X, I decided to run the PuTTY app and try some tests. The first test I chose was the Transmitter test. Using a SotaBeams Dummy Load and an MFJ-813 meter, I could see that it was putting out a solid 5W.The main LED was flashing 3 times during tx, as it should.
Next up was the RF FILTER sweep and I wasn't expecting anything good from it. I was right to feel that way because ever time I ran it, it swept up to 100% and then completely locked up. Ctrl-Q didn't work and I had to force the whole app to terminate. This app works perfectly with my Rev.1 QDX.
Thankfully, I have my original Rev1 QDX build to play with. That works superbly.
2) Return it to me in Turkey to solder on a new C38 (SMD)
3) We send you a whole new kit - NOT a preferred option!
4) Find any similar capacitor, or higher value, which is an ordinary through-hole component, and solder one end of it to the appropriate wire of the trifilar transformer, and the other end to a convenient nearby ground point.
Once the cap was soldered, I checked the AA,BB,CC connections and all was well, so I laid down a small piece of tape to prevent the cap legs touching anything they shouldn't - just a precaution.
Output voltage: 1.25-36V continuously adjustable
Over 3A, attached the heat sink.(recommended for use within 4.5A for long time use)
Output power: recommended for use in below 75W
Working temperature:-40 to +85 degrees
Operating Frequency: 180KHz
Conversion efficiency: up to 96%
Load regulation: S (I)<0.8%
Voltage Regulation: S (u)< 0.8%
Short-circuit protection: Yes (the limited current is 8A)
Over-temperature protection: Yes (automatic shutdown when over-temperature)
|16 JAN - UK to JAPAN on 4W 😃|
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