Finishing off the RF I/O stage means winding 3 toroids and two transformers on relatively smallish cores (T37, T25 and a BN-2402).
(Those are T30 cores in the picture...accidentally grabbed those instead of the T37 cores)
Took me about an hour to wind all the cores and get them soldered onto the board. For the transformers, I think I spent more time checking and rechecking the leads to make sure I had the primaries and secondaries sorted out properly.
Four bifilar turns is a lot to stuff into a BN-2402 core. It was a pretty tight fit with the AWG30 wire but I was able to cram it in.
With the toroids and transformers soldered onto the board (yay for heat stripable magnet wire!), this is what the top of that section looks like now.
Mixer stage is next.
Started on the non-toroid/transformer parts of the RF I/O and switching section of the build. Nothing too difficult with this section. Four SMD capacitors on the back of the board. On top are through-hole resistors, caps, and transistors.
The holes for the transistors is pretty close together, so to make inserting them (TO-92 package) easier, use some needle nose pliers to straighten out the outer legs. The transistors slip right into the holes without having to force them in because of the bend in the leads.
The BNC connector is also attached to the board at this stage. The one supplied with my kit has an all metal body. Soldering the two ground pins to the board takes a lot of heat. I ended up having to hold my soldering iron on the pins for close to a minute before they got hot enough to get a good solder joint. I suggest doing the BNC connector last. Once you've got it soldered on, it stays pretty hot for a while.
Top and bottom of this section so far.
Off to go wind some toroids and transformers.
On to the dividers stage of the build. Only 4 components here: a 74AC74 dual flip flop, a SMD cap and two resistors. The pin spacing on the 74AC74 is relatively wide, so it's pretty easy to solder. The blob and wick method will work, but it's also pretty easy to do each pin individually. Just have to make sure you get the orientation correct.
Top and bottom of the divider section of the build.
Here's the top and bottom of the whole board so far.
Next up is the RF I/O and Switching stage. Lots of stuff in that stage including a bunch of toroids and transformers, so that will probably take me a couple of days to do.
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.
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.
Just noticed the results for the 2015 North Carolina QSO Party are up. I submitted my log in the Single Op Out of State Phone category and ended up 16 out of 66 submissions in that category with 4070 points. Not anywhere near close to the big guys with scores in the 5 digits, but I'm pleased with it.
It's a fun QSO party to play in and looking forward to the next one.
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.
CARS has set up an operating day at the club station, WA4USN, on board the USS Yorktown for this year's ARRL Rookie Roundup (SSB). For Rookie Roundup purposes, a Rookie is someone who was licensed in the current year, or within the past 2 years (2013, 2014, or 2015). If you're a rookie or new ham and want to experience the HF side of amateur radio or just want to operate from the club station (it's a pretty neat place to play radio from), this is your chance!
The club room will be open starting at 1PM, April 19. Rookie Roundup starts at 2PM EDT and goes to 759PM EDT (1800 - 2359 UTC). If you're interested, drop me a note and I'll put you in touch with the proper people.
Spent some time playing in the Georgia QSO party this weekend. Band conditions were pretty terrible this weekend and I only worked a handful of stations on Saturday. I couldn't even hear WWV on any of its frequencies, which is really unusual. Normally I can always hear the 10MHz WWV signal, but this weekend it wasn't anywhere to be heard. Later in the evening the 15MHz WWV signal popped up, but that was it.
Spent most of Sunday at the radio tuning around 40m looking for more GA stations. Did a little better and ended up the weekend with 42 QSOs and 34 counties.
- 2 AB4 stations.
- Worked KK4UBQ again. Worked her last year in the 2014 QP when she was signing as KK4UBQ/AG.
- More QSOs, more counties than last year (although that wasn't hard to beat).
Had a good time tuning around the bands, even though propagation was down in the dumps.
Band QSOs Pts Mul
7 42 42 34
Total 42 42 34
1 Mult = 1.2 Q's
The Si5351 breakout boards all work, at least according to the frequency counter, so I thought I'd put the oscilloscope on one to see what was coming out. I just connected the output of the Si5351 board straight to the oscilloscope using an SMA/BNC pigtail. I'm sure it's a totally incorrect way of doing it, but all I wanted to see was if I got a waveform and if it changed when I changed the Si5351 frequency.
I've been told that the Si5351 output is a square wave, and at kHz frequencies, that's what I get. This is the 10 kHz waveform. Nice looking square waves.
Going up a few orders of magnitude to 1MHz, the shape of the waveform loses its squareness, most likely due to the way I've connected things (impedance mismatch, improper loading and all that). But, as the time base shows, it's a much higher frequency signal.
At 10 MHz, there's even more distortion of the waveform, but definitely higher frequency.
Up at 20MHz, things are looking pretty triangular.
- My Si5351 board really works! Yay!
- You can't just connect things willy-nilly to an oscilloscope and expect good results. (I already knew this, just wasn't important for this purpose.)
- There are still some things I need to learn about using this particular oscilloscope.