Category: Kits and things

Although the 3.3V voltage regulator seems to be dead, I decided to press on with the build. So far, this RXTX kit is proving to be one of the more challenging ones I’ve done so far. Lots of parts, small-ish components and closely spaced holes for the through-hole parts.

On to the local oscillator section today. The most challenging part in this section is the Si570 oscillator chip. The pads for pins 1-6 are pretty large and easy to solder. Pins 7 and 8 on the sides of the oscillator have pretty tiny pads though. This means it’s pretty important to position the Si570 properly. There’s plenty of room to position the Si570 up and down, but too much to one side and you end up covering up the pad for either pin 7 or 8. Cover them up too much and you may not be able to make the connection between the oscillator and the pad. I think with mine, I may have a dodgy connection at pin 7. I’ll probably find out in a little while once I get around to replacing that voltage regulator.

Also I forgot about leaving off C55, so I’ll have to take that off when I get back to working on the board.

The rest of the local oscillator section was a few more surface mount capacitors and through hole components. The first of many transformers and toroids is in this section too. Pretty easy, although a little bit of a challenge with the close hole spacing. You definitely want to use a small pointy soldering iron tip for this kit.

The top and bottom of the board so far.

After cobbling together a power cord to use with the Astron power supply, I was able to verify the power section on the RXTX board. Was getting just under 13V in and measuring 5V where there was supposed to be 5V.

Then I started on the USB power section. This is a section that’s isolated from the rest of the board and has the first of the SMT components to solder on in the project: a 3.3V voltage regulator (LP2992) and some capacitors.

Got everything soldered on easily enough, but when it came time to test, I wasn’t getting anything on the output of the voltage regulator. There was the 5V USB voltage going into the voltage regulator, but nothing coming out.

Rats.

Not sure if the voltage regulator got cooked in the soldering process, zapped by static, or if something happened to it while it was sitting on the shelf.

Guess I’ll have to order another one. Fortunately they’re not terribly expensive ($1.09 each for 10 from Mouser.com).

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

Next section is the local oscillator. I may not be able to test it with a bum voltage regulator, but I think I’ll press on anyway.

It’s taken me a few years to get to, but I finally started working on the Softrock Ensemble RXTX kit I picked up a few years ago.

This is a much larger board than the Softrock Lite II I put together a while ago. A larger board, and a lot more parts (especially toroids).

Started off with the power sections yesterday, which was pretty easy to do. All through hole stuff. The bank of filtering capacitors was a little bit of a challenge, mostly because the holes are pretty close together and it’s not hard to accidentally bridge the contacts.

Haven’t powered it up to test yet because the power jack is a 2.5mm center pin, which none of my wall warts will fit. I’m planning on wiring up the included plug with powerpole connectors on the end. That will let me use the Astron power supply on the bench.

Here’s the current progress. USB power section is next.

Finished assembling a non-TCXO version of the Etherkit Si5351 breakout board today. With three boards worth of experience behind my back now, this one went pretty smoothly. Set this one up to use in a breadboard like board #3.

Then it was off to test them out. I used Jason’s Si5351 Arduino library (as of this writing, the ‘jason’ branch is the most current one) and one of the example sketches with one of my *duino boards, connected the M³ frequency counter and wired everything up.

Much to my surprise, the first board (with the TCXO) worked, and the frequency was pretty much bang on, at least to the resolution the M³ meter is capable of.

The non-TCXO board I assembled today was off by a bit (~900 Hz), but Jason says that’s normal for the regular oscillator.

The other two TCXO boards worked as well and were right on frequency.

Now I need to work on more precise frequency measurements so I can work out the calibration offset for each of the boards.

Finished assembling the last of the Etherkit Si5351A breakout boards I received from Jason‘s Indiegogo campaign. Since I had three of them to play with, I decided to do a few different configurations.

Board #1 is a pretty conventional setup with the header pins pointing up. Lays flat on a surface and could be mounted inside an enclosure if needed.

Board #2 I used female header pins to make interfacing with my *duino boards easier, since almost all the jumper wires I have are male/male.

Board #3 I set up to make it easy to use with breadboards. The header pins are pointed “down” so that I can stick the breakout board into a regular breadboard. I also added female headers to the output in addition to the SMA connectors.

I still need to test the boards out to make sure they actually work. I think if I’m going to have any problems with the boards, it will probably be with the soldering of the Si5351A chip.