Tag Archives: flea market finds

Slacker Week

Oh, I’m a baaaad boy…

I have been busy, but not so busy that I couldn’t get a small post up, what a slacker. I just wasn’t up to it, so this week is catch-up week.

The clear bins on the left replaced one of the black drawer units and brought a bunch of stuff up from under the bench

One thing that got done was making some component storage changes on the benchtop. There was a bunch of stuff under the work surface that if I wanted a component I had to pull out and unstack containers to get to parts. Now most of the components and parts are on the benchtop. Staying organized is hard work. 😉

The Beach 40 is getting closer to completion. I have all of the sections done(ish), I need to go back and swap out a pair of capacitors in the Audio Amp and test the RF Amp section. The biggest thing I am behind on is posting updates to the project page which I will be doing this week.

I have a bunch of day-job stuff that I need to get done this week as well so it will be a bit of a crunch on time so I don’t see much solder melting in this weeks schedule but I do believe I’ll be up and running for Field Day, *knock on wood*.

On Saturday the De Anza Electronics Flea yielded some sweet fruit. A very nice edition of Andrew P. Peabody’s 1873 A Manual  of Moral Philosophy in great condition. Another awesome find was a Millersfalls No. 2 egg beater style hand drill, also in really good condition. The crank handle needs a little straightening but the drill is in great condition for daily use. Last but certainly not least was a bag-o-relays. Which is what I was specifically looking for at the flea. Thirty eight relays, all good for radio work, and only $20.

A really good flea market day, something for the mind, something for the hands, and something for making radio waves. What more could I ask for.

Sunday was the Bay Area Radio Builders Club meeting in Cupertino. A small gathering but plenty of radio building chin-wagging along with some show-and-tell. Topics ranged from my DSB transceiver to a Raspberry Pi controlled HT set up as an Echolink station with many more abilities under the hood, and the clubs TAK-40 radio build progress. (TAK-40 link to QST magazine article PDF)

That’s all for now, the day job beckons.

Until next time, 73,

New-To-Me Signal Generator

120 kc (kHz) to 200 mc (MHz)
120 kc (kHz) to 200 mc (MHz)

On Saturday I picked up a few things at the De Anza Electronics Flea Market. The most impressive acquisition would be the Lafayette Signal Generator for $20.

I have been needing one and I was dreading the prospect of having to build one and having a tough time without the right tools for calibrating it, so this was a great find and a steal of a value, though I didn’t know it for sure until today.

One thing I have learned about buying used electrical/electronic equipment, particularly in at a flea market, is that you have to take your time and open it up, get documentation, inspect and clean the equipment before attempting to use it, or plug it in for that matter.

20150414_075130 Sunday was opening day. I noticed right away that I would need to replace the power cord grommet as it was in two pieces. I didn’t actually get to anything else until today.

Today I inspected all of the wiring and components, looked for hot spots and anything that would indicate an over heat. Having found nothing of the sort I moved on to cleaning, which there was surprisingly little to do. I made sure the tubes were cleaned and had no fingerprints on them. Now that I have a piece of tube equipment I will need to get a tube tester. 😉

With the cleaning done it was time for the plug-in and smoke tests. No pops and and no smoke! I let everything warm up and burn in for a good twenty minutes before starting any tests.

Testing with the oscilloscope began with the AF (audio frequency) side of the generator. After the twenty minute warm up period the “approximately 400 cycles” audio tone as specified in the manual turned out to be stable at 388 cycles (Hertz). I can work with that.

“kc” is kilocycles. The term is essentially the same as the more familiar kilohertz along with “mc” megacycles being the same as megahertz. The change over in terminology occurred slowly from the mid 70s to the mid 80s. Many hams still use kc and mc. I use them interchangeably depending what I am referencing or who I’m talking with. This piece of equipment has frequency labeled on the dial as kc and mc.

20150417_152319Moving on… The generator did its first diagnostics job with a portable amplifier I have had for a very long time (the one on the right). I clipped on the amp to the audio out and it turn out the volume control on the amp is trashed from banging around in my tool bags for a couple of decades so I will need to replace the potentiometer in that this weekend.

I then moved over to the RF (radio frequency) side of the generator and clipped on the oscilloscope. The RF side is divided into 5 switchable bands. I checked each band by referencing the frequency on the dial with the frequency on the O-scope. All five bands checked out very closely to the dial. A little lead or lag here-and-there, but overall pretty close for this equipment and its age which I’m guessing is about as old as me (made in the mid/late 60s).

20150417_152206The frequency counter I purchased last year has been giving me problems. New equipment, cheap (figuratively and cost), and no manual. With the help of the new sig gen and the oscilloscope I managed to fix a couple of minor problems and figure out the modes on the counter in the process. Looks like the electronics bench is finally coming together.

Now that I can check the receivers I build I can also check the transmitters I plan on building. I can also check portions of the radios as the construction moves forward. I plan on building more of my own test equipment but it’s nice to have a reference point or two to calibrate off of.

I also did some diagnostics on the 40 meter direct conversion receiver project and updated the project page… some very interesting results, you should take a look. 🙂

A productive day I think.