Free lab power supply

There are several sites on the internet to get plans to convert an old computer power supply over for use as a small voltage power supply for experimental uses. I wanted one to use on my breadboard to mock up circuits, and to use to power some of my small regenerative receivers I have built. Here is what I ended up with. I found a computer power supply (dumpster find.) I ended up putting it in a black project box. I drilled holes in the top and each side of the box to add the computers fan to help cool the interior. Basically you combine all like colored wires and test what voltage you come up with. Mine was noisy when I tested it with one of my small QRP transceivers. I added some ferrite clip on type beads from the junk box collection.

SIde view of the power supply. You must have a load on these supplies or they will not power up.

I added a power up LED and a push button on off switch. Works great and best off all it was (nearly) free.

Tracer/Injector R.F. Probe Kits

I picked up a Hendricks Tracer/Injector Kit and an R.F. probe kit a couple weeks back.
First one on the table was the Tracer/Injector kit. Here is their product description from their website.

The Hendricks Tracer/Injector probe is an easy to use, handheld, piece of test equipment for diagnosing amplifiers, receivers and transmitters. It incorporates an LM358N, integrated circuit, half of which is the audio signal injector and the other half a tracer, incorporating a product detector to allow you to locate problem stages. With this tool you will be able inject audio signals through the various stages of your problem circuit, or trace signals from the front end thus narrowing in on the problem. It is a completely self contained, handheld device, using an inexpensive readily available battery.

I got started this morning and before I knew it, it was finished. Yep I forgot to take pictures until after I put on the final shrink wrap tube.

The whole thing is encased in shrink wrap tubing, but you can put it in your own case. A quick test with an earphone verified it was working.





Next up was the R.F. Probe kit.

A brief description again from their website.

The Hendricks R.F. probe is a handy test device to have in your shack. When used with an inexpensive high impedance digital voltmeter (typically 11 meg ohm input impedance), you can measure RF voltage in your solid state circuits, and trace RF through your new designs or malfunctioning circuits. You will be able to detect RF voltages in the range of .25v to 50v, and accurately measure voltages in the range of 1.0v to 50v, the range of the 1N34A diode used in this design, well up to 30mHz. This design is shielded to prevent picking up unwanted stray signals, or broadcasting them to other stages while testing.

Assembled board with components.

I comes with copper tape that you wrap around the PVC tubing that acts as shielding.

Completed probe. The hardest thing about this kit was putting the screw through the PVC tube body and aligning it with the nut on the PC board. Both of these were simple projects perfect for killing a little time in the shack. I am sure I will get good use out of both of these tools.

Here is a link to their site. http://www.qrpkits.com

National NC-300 project

Nice National

National NC-300 project

Working condition, has a few mods:

1. previous owner added a Lower / upper SSB switch on the front panel.
2. also a coax connecter so-239 was added to the back.
3. home brew XCU-300 crystal calibrator circuit added

Finished the Hallicrafters SX-99

A new dial cord was needed. I tried a few suggestions I saw on the web. Bead string was one it worked fine for a few turns and then it started to unravel and slip! Off comes the front panel dials lamps.....

A better suggestion I found was fishing line, the braided type with a core material. This actually worked. ( it got a real nice workout, I DID not want to take the front panel off again) I did rough up the spindle on the tuning shaft with 800 grit sand paper just to make sure it did not slip. Alinement was painless. Works FB now!

I decided not to paint it for now. I did do a wax job on it to shine it up a little. It has character, it has seen a lot in 50+ years. How does the matching speaker look?

Lots o'dirt here

First a little house keeping to clean off the years of crud.

Looks a little better. Some hand cleaner with a little denatured alcohol as a chaser does wonders on this stuff.

The old caps "Tiny Chiefs" and a few paper caps have to go. There a a few out of tolerance resistors that I will replace also. Bad news is the 3 section twist can cap has one 10MF section out of tolerance too.

If you need replacement for these you can try to cut them apart and re stuff them. I am lazy, I just order new ones from Tom N0JMY at
www.hayseedhamfest.com

All recapped and ready to test.