As you may or may not know, a few of the club members are experimenting with APRS. The goal is to evaluate how it could best be used by our group for EMCOMM and for radio fun.

Typically to use APRS you need a TNC, but many of us do not have TNC's. The rest of us don't necessarily want to buy a TNC, they can be quite expensive. There are some cheaper alternatives, such as RigBlaster and SignaLink USB, which allow almost as much flexibility as a full TNC. Then there are even cheaper alternatives, such as TNC-X and TinyTracker, which are great if you need a dedicated APRS only TNC. However the cheapest option is a little project from the June 2009 QST. The QST article, titled "A Sound Card Interface for FM Transceivers", provides a everything you need to know. One correction to the QST article, they list the isolation transformer as Mouser part # 42LX016-RC, the correct part number is 42XL016-RC.

For those who do not have the June 2009 QST I have provided a list of of all the parts below.

The circuit board is available from the author, you can order one sending $5 and a self-addressed, stamped envelope to:

KH6TY
335 Plantation View Ln
Mount Pleasant, SC 29464.

The components are available from mouser.com.

Three 1µF 50V electrolytic capacitors.
One 10µF 50V electrolytic capacitor.
Two 1N4148 switching diodes.
One panel mount 1/8 inch stereo jack.
Two 2N2222A or any small NPN audio transistors.
One 100kΩ 1/4W resistor.
One 47kΩ 1/4W resistor.
One 330kΩ 1/4W resistor.
Two 4.7kΩ 1/4W resistor.
One 1:1 audio isolation transformer Mouser part number 42XL016-RC.

If anyone needs a circuit diagram replay back to this post.

Any chance of getting up a group order and have a Tech day to put them together?

I have contacted Skip. The maker of the boards. He is out of them. He will only reorder them when he has a request for 100 boards. I have put in a request for 20 boards. I will be happy to make up a bulk order of parts from mouser for the parts needed. I think that between Henry/Clayton and Newton clubs 20 would like to build one. If no one wanted to use the boards they would make a good training project.

I know that Judy (K4YLE) wanted to build one and I am pretty sure that Charles (N4CBJ) did as well.

We just need to promote it on the weekly net, and I will send an email to everyone with links to this post.

I would love to build one. I need the soldiering experience.

I would like to just finish mine... I will try to come to the event to help out though and as offered before we can hold it down at the hanger if you like. I only have one more cap to solder and hopefully we can test these things out. Things are starting to get back in line with my business so that I have a bit more free time...

I now have the components to build 20 soundcards. I do not have the boards. I do not know if the guy will ever get some more boards. I would suggest getting Radio Shack pn 276-150 board and building it up on it. If you want to get together and build up some boards or if you just want the parts let me know.