I knew going into the SoftRock RX Ensemble II project that it wasn’t going to be easy. With 15 toroids, a slew of surface mount components and a range of through-hole work, all packed into a 2×4.5-inch board, there is a lot that can go wrong.
My buddy KN4QD has experience with these kits and offered to give me a hand with mine this past weekend. I was grateful, for I didn’t have any of the items needed for surface mount work: a fine-tipped soldering iron, very small diameter solder, a flux pen, solder-wicking braid, fine tweezers, etc. I haven’t built a kit in a year or so, therefore my skills with the volt-ohm meter and iron were very rusty.
Following the instructions on WB5RVZ’s site, we began the build with optimism. We made it through the first two build stages, with the main hang-up occuring when I managed to solder-bridge two of the contacts on the smallest SMT component in the kit: the flea-sized voltage regulator, which has five leads altogether, three of them a hair’s breadth away from each other. After about an hour of heating, wicking and scraping, we managed to clear the bridge, but testing at this stage was showing numbers that were off.
Using a loupe, I examined the problematic voltage regulator and noticed that one of the contacts wasn’t even touching the trace on the board. A blob of solder later, and we were getting the proper testing values on the VOM, and it was off to lunch with an optimistic outlook for the rest of the build.
Stage three of the build involved installing the heart of the board, the tiny Si570 oscillator. No problems there. SMT is beginning to agree with me. We also encountered our first wound component, the binocular core inductor, which involved a bifilar winding of very fine magnet wire, which is apparently encased in enamel that is impervious to heat and acetone.
Once everything was in place, it was time to connect the board to the computer via USB and see if it was recognized and controllable. Once we installed the proper drivers and software, we connected the board and launched the Si570 programming tool. The program reported a “green light” and oscillator control seemed to be working. Looking good so far, but upon connecting the VOM to test some recommended values, we were seeing numbers that didn’t make sense.
We touched up some solder joints, checked and re-checked our work, but continued to come up with numbers that were way off from those in the build manual.
As a result of those early tests, confidence is low as I continue to plow through the build. I fear that I may have damaged the tiny voltage regulator when we were trying to clear the solder bridge. While we did work with a grounded wrist strap, there could be ESD damage to one of the ICs, perhaps there is a solder joint on one of the SMT capacitors that isn’t making solid contact, perhaps one of the components was simply bad. There are even reports that there have been bad batches of the Si570 chip. There are just so many factors.
My goal with this kit was threefold. One to have fun building a kit, two, to gain experience with SMT soldering, and three, to have an SDR receiver on my shack computer. For now, at least two of the three goals have been met — although at $67 a pop, it was an expensive lesson in SMT work. I certainly hope it works in the end, but I’m not holding my breath.
Going Mobile, Part II
I decided to buy a mobile rig on a whim last week after a Yaesu FT-8800 showed up on a local ham swap board. I’m now the owner of this used rig, complete with box, manuals, all the original mounting hardware, programming cable, separation kit, two antenna mounts (one a magmount, the other an NMO) and a dual-band antenna.
The rig itself is practically brand-new. I hooked it up to a 12V SLA battery and gave it a test drive on some local repeaters. Everything looked and sounded pretty good. Now I just need to explore some installation options for my Focus hatchback. At least I’ve finally located the grommet in the firewall through which I will be able to run my power cable. I’m thinking I will just attach the radio’s main chassis to a piece of board using the included mounting bracket, and sit the rig either in the rear cargo area or the rear passenger footwell, then install the rig’s faceplate in the front with a gooseneck and seat-bolt mount. I often have to transport an elderly family member, along with her wheelchair, so it will be nice having the flexibility to remove the main radio unit easily if the need arises.