A trio of QRPGuys kits

A while ago (back in October) I ordered a few kits from QRPGuys: a dummy load, mini-paddle, mini keyer and two digital frequency counters (PTH and SMD versions).

I finally got around to assembling the dummy load, paddle and keyer over the past week.

QRPGuys kits
Iambic paddle, mini-keyer and dummy load from QRPGuys

The dummy load was the easiest to assemble, and parts placement was pretty obvious (I’m only a little bit bothered because the resistors don’t line up…). 5 minutes of soldering and you’ve got yourself a nice compact little 12 watt dummy load that also lets you measure power output via a voltage measurement.

The mini-paddle was only a little more difficult because of the size and length of the screws being used to attach the paddles. Still a relatively easy build, although you have to be careful with the alignment of the little PCB pieces that are soldered onto the base. The hardest part was getting the little nuts that hold the paddles secured. There’s not a whole lot of space to work in, you have to hold the screw, spacers, washers and metal paddle part while trying to get the nut on, and there’s not a whole lot of screw remaining to get the nut started on. Moderately difficult to assemble.

In terms of parts count, the single lever keyer/paddle was the largest kit, but easier to assemble than the iambic mini-paddle. On the electronics side, the only thing I had to consult the assembly manual for was to find out the correct orientation for the 1N4148 diodes. Placement of all the other parts is pretty obvious from the silkscreen outlines. On the keyer side, assembly was similar to the mini-paddle, but with only one lever to worry about, getting it put together was significantly easier. I did end up leaving off two nuts for the two screws that serve as contacts for the paddle. With the nuts, the screws were just too far away from the paddle. I don’t know if the screws I got were just too short to begin with, or if the kitting changed but the instructions didn’t get updated.

True to their mission, these are fun, inexpensive little kits to put together. Looking forward to working on the frequency counters next.

 

 

Ensemble RXTX build – Driver/PA

The driver/PA section is the final section of the build.

Three capacitors are the final SMD components left to solder onto the back of the board.

Capacitors for the driver/PA section
Capacitors for the driver/PA section

Two binocular core transformers are part of this section. You might be tempted to do these last, but I suggest making them the first components to install. The top of the board is starting to get pretty crowded at this point and you’ll want a bit of room to thread the wires for the transformers through the holes. Same for the RF choke (RFC1, which I noticed I inadvertently left out).

The transformers themselves can be tough to wind. Make sure you pull each wire tightly through the hole or you’ll have a hard time fitting all the windings in.

The three BS170 FETs get covered up by a heatsink and pad. The 2N2222 transistor also gets a heatsink treatment. There are a few components that get partially covered up by the heatsinks, so make the FETs and 2N2222 the last parts you work on.

Everything else is pretty simple and should go together without any issues.

Ensemble RXTX driver/PA section
Ensemble RXTX driver/PA section

The top and bottom of the (practically) completed board.

Ensemble RXTX top
Ensemble RXTX top
Ensemble RXTX bottom
Ensemble RXTX bottom

 

Ensemble RXTX build – TX mixer

The TX mixer section doesn’t have quite as many components as the previous section, but there are a few band specific components including a toroid and transformer so you’ll want to make sure you have the right band selected if you’re following the WB5RVZ build instructions.

Like the RF mixer stage, the only SMD components are the FST3253 IC and three accompanying capacitors.

Ensemble RXTX TX mixer
Ensemble RXTX TX mixer

The through hole components consist of a 3904 transistor and a few capacitors and resistors. Watch out for accidental solder bridges between the closely spaced holes of the transistor.

Both the L1 inductor and T2 transformer have a lot of turns to wind onto a relatively small T30 core. If you have some 28 or 30 gauge magnet wire that’s a different colour than what comes in the kit, use it for either the primary or secondary winding on T2. That will help make it easier to separate out the T2 wires before soldering onto the board.

Ensemble RXTX TX mixer toroids
Ensemble RXTX TX mixer toroids

Here’s the top and bottom of the board so far.

Ensemble RXTX Top
Ensemble RXTX Top
Ensemble RXTX bottom
Ensemble RXTX bottom

One more section left in the build: the driver/PA section.

Ensemble RXTX build – TX op amps

Lots of parts to solder on in the TX op amp section, but most of them are through hole. No band specific compnents to worry about.

You might be tempted to place them all at once and then start soldering, but with all the dangling leads you end up with, it can make getting around with the solder and soldering iron a bit difficult. I found it easier to place a few components, solder, trim the leads and then repeat with a few more components.

I cross-wired JP1 here instead of jumpering them straight across, based on the notes in the build instructions. May end up having to change this, but we’ll see.

Ensemble RXTX TX opamps top
Ensemble RXTX TX opamps top

Two SMD op amps and accompanying capacitors go on the bottom of the board. By now, soldering the SMD components should be pretty easy, even if you’re new at working with them.

Ensemble RXTX TX opamps section bottom
Ensemble RXTX TX opamps section bottom

Getting near the end of the build now. Only two more sections left: the TX mixer and PA. TX mixer section is up next.

Ensemble RXTX build – RX Opamps and Output

The RX op amp/output stage is another relatively easy one. A handful of non-band specific through hole parts, 3 SMD caps and the SMD op amp. Nothing too difficult here, although again, you’re dealing with pretty tight quarters with the through hole parts.

The line-in (which goes to the line in port on your computer’s sound card) is the largest component to deal with.

The instructions for wiring JP2 in the build instructions were a bit confusing. My interpretation was that if your jumpers crossed over (jumper wires formed an X), then you could use any of the software mentioned (PowerSDR, Rocky, Winrad). In this configuration, you’d need to set a “Swap IQ” setting in Rocky/Winrad. If the jumpers were straight across, you could use Rocky or Winrad, but not PowerSDR.

I chose to jumper them straight across as shown in the WB5RVZ build instructions.

Top of the board for this section.

Ensemble RXTX jumpering
Ensemble RXTX jumpering

Bottom of the board

Ensemble RXTX RX opamps/output section bottom
Ensemble RXTX RX opamps/output section bottom

Next section is the TX op amp. Lots of parts there.