Monday, April 23, 2012

SoftRock SDR Kit - Power Supply

I put off starting my SDR kit for about a week, and I now realize that probably means that "kit month" will extend into May (boo hoo). This kit is a bit more formidable than the previous two, in part because of the number of parts, but more so because of their small size. It's going to take some time.

The parts inventory

I thought today would be a good day to get a start on it, since it is my birthday and therefore I get pretty much free rein over my activities. Some blogging, Skyping, and a couple of coffee breaks with chocolate chip cookies, and ... where did the time go?  And I hadn't even printed the kit manual yet (an also formidable 71 pages!). Once I got the manual and headed down to the bench it was afternoon. 

Nonetheless, I thought I could make some good progress, but it was not to be. All I was able to accomplish was to put the components together for the 5V power supply and then I got stuck running the PS tests. Those tests are 3-stage - 2 current tests one with one without a limiting resistor, followed (if the previous were succesful) by a voltage test. Trouble was, I couldn't get any current reading at all. 

The power supply done
 I double-checked that I had voltage coming in (is it plugged in?), fiddled with everything that could have a loose connection, ran resistance checks according to the circuit schematic and sat befuddled. Everything checked out, but it seemed dead.

After a few more minutes of thought I popped the back off my trusty DMM and found the low-current fuse was blown! Duh. Of course, I don't have a spare 200 mA fuse handy, but I did remember a backup DMM I had in another tool box. You'd think I'd be smiling by now, but alas, this DMM also showed no current. This time, however, re-setting connections did bring it to life with current readings of about 2.2 mA. The voltage checks also panned out fine, so it looks like I somehow managed to place about six parts without error. LOL!!

I'd hoped I'd be able to get some radio time today, but it seems our rainy season has decided to start a month early after our exceptionally dry summer and the lightning storm in progress at this moment precludes that. Well, there is always tomorrow!

2 comments:

  1. Good morning Casey, kit building has always been one of the parts of the hobby I really look forward too. At this time for me there is nothing on the bench with regards to kit building. Keep us posted with the progress of the build.

    ReplyDelete
    Replies
    1. GM OM. Will do on the posting about the kits. Hope to get a little more time on it today. Looking forward to my first SMD IC soldering!

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Thanks very much for your comment! 73, Casey

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