Eugene

Building the Softrock Lite II

Finally got around to starting one of the Softrock radios I got a few months ago. Decided to start with the Softrock Lite II receiver since it was the easiest and didn’t have too many SMT components to put on. Most of the components are through-hole, with a few SMT capacitors, ICs and an op amp. Perfect for starting off with SMT work.

It’s a pretty easy build, and the build instructions are pretty thorough and informative. The instructions break up the build into the different sections of the radio, explain what it does and provides the schematics, list of parts, where to put them on the board and tests afterwards.

I did run into a couple of problems with getting the SMT capacitors on. One of them was the wrong one (didn’t take note that one set was marked and the other wasn’t), and two of them I put in the wrong orientation because I wasn’t paying attention to the diagram. Other than that the SMT work turned out to be a little easier than I thought it would be.

The build starts with the power supply part of the radio. All through hole stuff, except for one SMT capactior, so pretty easy. Just need to pay attention to the orientation of the diode.

I used a couple of jumper pins and used power from the MiniLab to supply power to the radio for testing. The oscillator part was next. Again, all through hole stuff and one SMT capactior here for this section of the radio.

Most of the SMT components are in the divider and op-amp stages of the build. There are 3 SMT ICs and the rest of the SMT capacitors that go on in this part. With a bit of practice from the first two SMT capacitors, getting the rest of the capacitors on wasn’t too hard (aside from not paying attention to orientation). The SMT ICs and op amp were a little trickier, but still not as bad as I expected.

Except for the inductor and transformer in the band pass filter stage, all the components are on the radio. Will need to study the section on winding toroids first before I try to make them. Then I’ll have to switch out the jumper pins for a more permanent power connection and then make up the computer and antenna connections.

Charleston Hamfest

The Charleston Hamfest is only a few weeks away on Feb 2. This will be the second hamfest that I’ve gone to so I’m looking forward to seeing what will be there. The first hamfest was the Atlanta Hamfest back in June (which is also where I passed the ham radio license tests) and was a lot of fun. A pretty decent attendance and a lot of neat looking gear. I wonder what this one will have.

Wifi router antennas

I thought I’d see what I got out of EZNEC for modeling the three antennas on the wifi router. I treated each of them as single wires at 2.452 GHz about 1m off the ground (not the floor). Each wire was 8 cm long (0.654 lambda) spaced 8 cm apart. Radiation pattern is directed perpendicularly to the plane containing the antennas, so I have two of them pointed down (the wifi router is mounted to the side of the desk) and one pointed off to the side (there’s a power strip that gets in the way of it pointing down like the others).

After reading through some of the original documentation for NEC learning about the somewhat arcane input format (like MCNP, it can be pretty confusing at first), I’m liking how EZNEC simplifies and hides some of the complexity, but is still accessible if needed. When I start getting into building antennas, I might have to get a copy of it.

New antenna model

I was able to find some EZNEC model files for a G5RV antenna including the feed line and tried to modify it to match my current antenna setup. 40m and 80m are pretty much the same, but the radiation patterns for 20m and 10m become a little more complex compared to my initial model.

10m

20m

Here’s EZNEC’s SWR plot

Modeling the antenna

Using the EZNEC ARRL version that comes in the ARRL Antenna book, I attempted to create a simple model of the antenna as it’s currently set up.

Using a tape measure and some very rough estimating, I came up with this plot of how the antenna is set up, without the ladder line in the middle (haven’t figured out how to add the feed line yet).

The far field plots EZNEC gives me look like this

80m

40m

20m

10m

The antenna model is pretty simple and nowhere near perfect. I’m probably missing a lot by not having the feed line included. Based on these rough simulations though, it looks like I’m warming a lot of clouds (ham speak for when your antenna is sending radiation mostly straight up).