A quick and failproof method I use is a small (3-12VDC) voltage source and a resistor in series, then I touch the LED leads to that combination. If it doesn't light up, reverse it. If it still doesn't

Regarding resistor colors, beware of the subtle difference between orange and red. The orange 3rd band on a 47k resistor and the red 3rd band on a 4.7k resistor often look identical. If you are missin

Nice product. I'm wondering why you used a USB-B connector rather than either of the 5-pin mini or micro USB connectors? That might have made the footprint a bit smaller, unless you already had plenty

Very nice "cooling" article. You probably should put some thermal compound between the FETs and the large solder pad on the circuit board, as that's the primary heat sink for those transistors. The wa

#qcxmini #magicsmoke

Switching the oscillator on and off or changing its frequency by more than a few kHz takes some amount of time. This might interfere with the full break-in operating mode and may not be the ideal solu

#qcxmini

Could that "grass" be when the actual NMEA data is being sent out of the QLG1? It seems to last about 0.5 to 0.6 seconds and might be present while the 1PPS signal is high, but we just can't see it. C

#progrock #qlg1

So the bigger question: after the blue fire, was the heat shrink tubing shrunken like you wanted it to be?

Hans, could you either add the TCXO connections to the schematic or add my diagram to the synth manual? Also, a photo of the ProgRoc synth board with the TCXO instead of the crystal. I have bigger ima

It was my understanding that he needs an X-ray view or track image of the synthesizer board, the one with the Si5351 on it, not the ProgRock board that it plugs into. If in fact his problem is on the

If you're going to be doing ANY SMD repair, definitely buy a Chip-Quik kit. It comes with liquid flux, which you apply before removing the IC, and before soldering on the new one. As the old IC is alr

Start at pin 14 and use an ohm-meter to trace the circuit per the schematic. Move past the FET and trace every component. There could be a broken trace when the board was etched. Hans may also have an

It's only a simple two-sided board. You can add jumper wires to the FET as needed according to the schematic diagram in the manual.

I live in Hamden CT, about 35 minutes from ARRL headquarters in Newington CT. Several years ago they sent me an order blank for their Travel-Plus repeater directory CD. I filled it all in, including m

Can you disconnect the secondary of T1 to check that 2.5V bias voltage? I don't know if the IC it feeds is passing that bias voltage to the circuitry to its right (on the schematic) but I suspect ever

When you installed the LEDs, did you orient them by the flat along one side, or the lengths of the leads? I've had some LEDs where the two orientations differed. The plastic molding was done incorrect

Most modern PCs have an electronic on/off button rather than a switch that interrupts the primary power. The PS has a 5V supply that's always on as long as the PS is plugged into the wall. This voltag

Also remember that the Heath Cantenna had an air vent in the top lid. The mineral oil and air would expand slightly when it got real hot, and the pressure in the can had to go somewhere. You don't wan

I know a lot of QRP Labs products can be programmed with a TTL-level serial protocol. The USB to serial adapter products that use a genuine FTDI USB serial chip seem to be the most compatible and reli

Looks like a bunch of nice improvements. From reading lots of posts here, it does seem as if a lot of people had problems with the 5k volume control lugs either disconnecting from the phenolic or losi

Yes, you should get 5V out of the regulator with no load. There are often small (less than 1uF) capacitors on the output of the 7805 regulators, sometimes tantalum. These have a nasty habit of shortin