Interface finished!

Tweetbutton tweet

k7ip Mon, 08/03/2009 - 09:41

Yes, he CAN be taught!

After arranging all of my soldering weaponry in order to begin work on the Softrock this weekend, I discovered that I had left behind my anti-static mat. Curses, says I, well, we'll just have to pull out the DEMI preamp and do some work on that. Hmmmm....first step in the instructions is to install the GaAsFET on the board, the very reason I bought the static mat in the first place. Curses. Fall back to plan C. Not wanting to waste all that workbench preparation, the old homebrew soundcard interface was on the list right after making some small repair work on an old Heathkit HM-2102 wattmeter. I have two of these, and Heath, in their infinite 1970's wisdom made band selection an option at build time by two different capacitor values in the diode rectifier circuitry. Naturally, these are both E-Bay acquisitions, and lo, they are both wired for 2 meters. Out with the soldering club and change that 12 pf to 18 pf. The calibration looks like it matches on both scales, so the other mod to make the calibration on the high power position adjustable doesn't seem necessary.

Having just spent some time reviewing various videos on SMT soldering in anticipation of working on the Softrock, I took a critical look at the solderingI had done on this home brew sound card interface a few years back. Yowee....did I REALLY do a construction job that looks like it was directed by an idiot and accomplished by a barely-skilled baboon? Oh, the humanity......

First thing I did was use up the better part of a whole roll of solder wick and get all the connections cleaned up on the original part of the board. Next was to find space for the PTT circuit which I left off the original, intending it to only be used with VOX. Since the Ranger 5054DX100 has no vox, we needed to add the typical opto-isolator keying circuit. Half an hour later, that was on the board and playing very nicely with wsjt. Or at least it was after I traced and rectified conflicts with the serial port that had been seized by Palm Manager.

The solder job, while probably not NASA High Value certifiable, was much better, so I went on to redo all the other connections. Let me extol the virtues of a flux pen! I admit that doing some rework for my last employer introduced me to it, but for personal use I had pretty much assumed that the flux core solder would suffice for everything I needed to do. Not so! At about $8, a flux pen is a marvelous little addition to the toolkit. It definitely makes the solder go where YOU need it to go. Sticky, to be sure, but that's handled with a little isopropyl alcohol and an old non-lint dishtowel scrap. Be sure to get some flux/acid brushes too, about $2.50 for three at Ace hardware.

I ran out of time before I could actually finish up mounting and soldering the various connectors I wanted to add to a project that was pretty much a wire nest, but the improvement is already evident. If there's time this week, I'll finish the job and see if it will really key the rig.

It was an enjoyable Sunday morning!

8/05 update

A week from today is the peak of the Perseids meteor shower, arguably the best of the year. The goal is to have the interface done and have the Moxon in a place where I can make some noise. For this event, I think I'm going to go with the FT-736/Mirage combo at home rather than roaming. Midweek ops make more sense there, as pesky work is going to get in the way. The overpowering question is WHICH COMPUTER? I've been procrastinating moving the desktop to the workbench/operating table for months. This might be a good time to make that move. On the other hand, the apartment lease is up in about 2 months and I'm itching to get away from the A. loud neighbors. B. Minor TVI C. Apartment dweller compromise antennae, and did I mention D. loud neighbors? With so little time left, I should probably be packing rather than thinking of spreading more radio stuff around the already crowded location.

8/17 update

I really shouldn't go back and read the older posts. I did make an unsuccessful effort to get the Moxon up on Tuesday night to try the Perseids. The arrangement for attaching it to the patio just didn't work for one person to handle. Enough said on that. Although PingJockey showed a total of 121 people present in some form, the dipole just didn't cut it with only WA7BBJ showing up direct, as usual.

But, I digress. This weekend was about more construction, and the homebrew interface was finally finished off and boxed. I need to make a couple of cables for it, but the electrical checkout showed that it works, and I expect that if I can overcome the weekly inertia at some point it will be usable from now on. Cross one project off that long list!

4/01 update

In typical fashion, I finally got around to trying to make this thing work with my assembled pieces. Unfortunately, the construction phase went a lot better than the actual integration part. I can't for the life of me get the serial line (newly added) to key properly. When not connected to a rig, the serial port toggles the PTT line just like it should. Connect it to the rig, it hangs in the transition zone and will not key the rig. With everything else that is going on these days, it's going to be a few more weeks until this gets resolved.