Lowcountry Contest Club Mesh Networking Symposium

Update: I received a correction for the date of the symposium. It will be on Wednesday June 14. RSVP by June 11.

Did you know there was a Lowcountry Contest Club? I didn’t know there was a Lowcountry Contest Club. Apparently they’ve been around a while.

Anyway, word came to me that they’re holding a Mesh Networking Symposium June 1014 at the Fleet Reserve Association in Goose Creek.

The Low Country Contest Club (LCCC) will be holding a symposium on MESH networks for amateur radio at the Wednesday, June 10, meeting of the LCCC at the Fleet Reserve Association in Goose Creek, SC at 1800.  We generally arrive at 1800, order food/drink if desired at appx. 1830, and start the symposium shortly thereafter.  Note that there is no “meeting,” just the symposium. Directions, etc. are at the bottom of this email.

Terry, N4TLF, and I have been working for some time on establishing a 2.4GHz link between our houses, so we could further investigate the use of MESH networks in amateur radio.  We have finally managed to establish the link, and are currently working on ways to improve it, and also make the link available to others.

To make a MESH network really useful we need more participants.  To that end we are inviting interested members of TARC and CARS to attend the June meeting of the LCCC, and will have (for lack of a better word) a symposium on MESH networks that will address
equipment, software, and problems involved in making a useful MESH network in the Charleston metropolitan area.  We should have an example of a MESH network set up in the FRA building, and a demonstration of at least one possible application.

If you know of a ham that is interested please bring them with you.  They do not have to be a member of any club; only interest is required!

This is a growing part of amateur radio.  We think you will find it interesting, and hope that this will help to get a MESH network established here in the local area.

I assume they mean Saturday June 10 and that Wednesday is just a typo.

The symposium date is June 14. RSVP by June 11 if you want to attend.

Ham radio mesh networking is becoming a pretty popular thing these days with projects like Broadband Hamnet and AREDN using COTS wifi equipment and custom firmware. For hurricane and storm prone areas like the Lowcountry, having an infrastructure independent communication network based on a mesh network over the ham bands could be a very useful thing.

I’ll be out of town at Southeast Linuxfest when the symposium is happening, but if you’re interested in going, RSVP to W4MEL at <w4mel at arrl.org>

Power supply: Out to the control board

I’ve finished tracing the power supply schematic out to the control board. I’ll go through it once or twice more to make sure I’ve got everything right, but I think I’ve got a fairly complete schematic of the power supply now.

Here’s the schematic so far.

Power supply schematic
Power supply schematic

I did run into an anonymous transistor type part with a red case that I wasn’t able to identify. Whatever markings were on it have been rubbed off, so there’s no way to really identify it anymore.

Mystery transistor
Mystery transistor

The base of the transistor (I’m assuming it’s the base anyway) is connected to pin 10 of the 723 voltage regulator while the emitter is connected to the bases of the power transistors. The collector goes to pin 12 of the 723 and the collectors of the power transistors. Checking with schematics for my Astron RS-35, there’s a TIP29 transistor in roughly the same spot, so I’m reasonably confident this mystery part is an NPN transistor of some kind.

Tracing out the control board was a bit tricky, but I think I managed to get it right (I think I’m missing the diode on the schematic though). I’ll need to recheck where the wires coming off the control board go in the rest of the power supply.

Power supply control board
Power supply control board

Quite impressed with the way this power supply was put together. Everything is soldered or screwed together nice and cleanly, and the wires are nicely dressed and bundled together with zip ties and string.

Except for the blown fuse, I don’t see anything obviously wrong with the power supply. I think I will look into replacing that AC input plug though before I try applying power to this thing.

Happy hamiversary to me!

Today is my 5th hamiversary! 5 years as a licensed amateur radio guy!

It’s been a pretty fun 5 years where I’ve learned a lot of new things and remembered a lot of things I used to know. The shack has been off the air for the past year, but once I figure out how to get the antenna back up in a mostly stealthy manner, I’ll be back to throwing RF into the sky.

I’m looking forward to many more years playing with amateur radio.

Power supply: Power transistors

I’ve traced the power supply schematic past the SCR and out to the power transistors that are attached to the big heat sink. This part of the schematic might be a little questionable because a lot of the wires are covered up or obscured by other components and a little harder to follow.

The schematic so far:

Power supply schematic
Power supply schematic

I’m up to the control board now. It’s small, but has a lot of wires coming in and out of it. Fortuantely it’s all point to point wiring on perfboard, so I don’t have to follow any PCB traces.

Power supply project: Input and filtering

Tracing out a schematic for this power supply has been pretty fun so far. It’s also been a good excuse to learn how to use KiCad.

So far I’ve made it past the rectifier and filtering capacitors up to the power transistors. I’m pretty impressed with the way the innards of this thing are put together. The bridge rectifier part took me a bit to figure out until I realized there were two different stud mount diodes in it.

Rectifier diodes
Rectifier diodes
Rectifier diodes
Rectifier diodes

I’ve come across a couple types of components that took me some searching to figure out what they were (still not quite sure what one of them is). This one in particular is one I haven’t been able to identify.

Mystery component. Diode? Transistor?
Mystery component. Diode? Transistor?

It’s connected to one of the outputs of the bridge rectifier and the control board at the top. At the bottom it’s connected to an air core inductor and parts that lead to the 2N5886 power transistors. A Google search of the numbers printed on it take me to a single page at a store that has it listed as a rectifier diode.

This is the schematic I’ve cobbled together so far. Things start to get a bit confusing after the rectifier, but I think it’s reasonably accurate.

Power supply schematic
Power supply schematic

I wasn’t able to find symbols for everything in the KiCad library, particularly for the connectors, so I just used something that looked reasonable.

This has been a fun exercise so far. The power transistor section will probably take me a while to figure out.