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I found this utube video about troubleshooting the QCX amplifier very helpful. https://www.youtube.com/watch?v=rUVLphjKaFQ -- KE4LJH Steve, Florida

Have a ver 3 QDX for sale.? Works great.? With case, wired for 12V.? Im just not too much about the digital modes. $80 Shipped contact at? ? n5mf at dfn . com Mark N5MF

Dear Hans, There are plenty of inexpensive 12VDC Regulated 2 Amp wall warts out there.?? I just use one of them and have been since QDX rev 1.??? I have had no problems at all and it makes it

Alan, Lower voltage in and lower power out both make lower heat. I see no problem in lowering risk to rig! I used 7809 bolted to case internally to keep voltage exactly right. It does run warm at 13.8

Hans, Are the frequency limits ignored during the filter sweeps? That is, can the start frequency be less than frequency min, or the maximum of the frequency sweep be greater than frequency max as set

knobs: if you have or make the right standoffs, you can use the supplied M2.5 screws and standard knobs. Conversely if you have longer screws you can make the supplied knobs work.

Dan, Hans has said he runs his at 13.8 volts as a test rig, no failures. But he recommends 12 volts to be safer. As Evan says excess voltage is dissipated as heat so that makes most feel more

The QDX manual states; If you wish to use a supply of 12 - 13 V the 3:2 winding style is more suitable and will produce 4 – 5 W output for 12 – 13 V supply. I started with the 9v build and it gave

Hi Hans, I will not run my 12volt QDX on anything over 12volts.? The output MOSFETs are not the only thing that will generate heat in the enclosure.? The LM78m05 will also need to dissipate another

Check the manual for your power supplies.? Many of them can be adjusted via a small trimmer on the main board.

I built mine for 9V, since Hans suggested that was preferred. However, if you look at the power curves Hans supplied, it looks like power outputs at 9V (9V build) and 13.8V ('12'V build) are about the

Are you talking about these links? Steve Fabricant posted these in a previous post.

Hi Hans, I’m using a 13.8v supply and 3x 1N4001 diodes in series worked for me to drop the voltage. They get warm but not excessively so… Before using the diodes the QDX case did get quite warm

How tough would it have been for them to simply send some sort of knob that actually worked? Well knobs for polyvaricons are not common. Usually you use a long enough (and not too long) M2.5 machine

IIRC there were several mistakes in the diagrams and instructions. ?For me the biggest issue is that the knobs simply do not work with the polyvaricons...... ? and, I'm a handy guy, and experienced

Hi Hans! I hope all is well with QRPLabs! I just had a nutty idea I thought I'd share with you. Please ignore this if you think it's silly or a waste of time or if you've already thought of it... The

Another note of encouragement. If you take it slow, and like Hans' says triple check each connection, you can't go wrong. Like travel, half the fun is getting there. Good Luck! --Al WD4AH

Hi, My QDX is nearly finished, and I now realize that all powersupplies I own give out 13.6 volts. That's a whopping 1.6 volts more than advised. I did provide for extra cooling of the BS170s, and I

Besides, just following directions (when building a new kit) isn’t really teaching you anything. If it doesn’t work and with help from others on this connection you finally figure out what is

OK, here comes some truth: if I can do it, anyone can. Due to the rigors of my career path, I have carpal tunnel issues along with arthritis in both hands...let's just say that my soldering skills