For the past few weeks we have been playing around with building a cheap simplex node. The idea was a simple RF node for around the house.
We started with the NiceRF SA828-U. This was a pretty simple single RF chip based complete UHF radio. At $22 plus shipping, worth a shot.
The Sa818 was also considered, but the SA828 was a more complete.
<https://www.tindie.com/products/NiceRF/all-in-one-walkie-talkie-module-kit-sa828-v-400-480mhz/>
One problem with the single chip radios is that you have no access to discriminator receive audio and to the modulator input, but it's cheap.
The nice RF modules do work, but was there a better way? The SA-828 was shipped from China and took forever to get to us in the States. We started looking around for a alternative. Enter the Baofeng BF-888. Available on Amazon, shipped from the US and $15 + tax shipped to Prime account.
A number of people have used the 888 for IRLP, EchoLink and AllStar nodes. One thing we wanted to do differently was to take receive audio freon the receiver before the audio anp. A web search will turn up everything you need to know to use this type of radio in a node.
Next was the USB interface. The DMK URI or the Repeater Builder USB RIM are both fine pieces of equipment and we highly recommend them. There are lots of CM108 sound FOB mods on the net. We used the WB2EDV carrier board. With all new parts a a sound FOB, total cost about $23
<http://www.repeater-builder.com/projects/fob/syba71-fob.html>
Last but not least, the node computer. Doug has created a nice BeagleBone Black node computer. <http://hamviop.org> We really like the BBB board but we wanted to try something else. Since we had quite a few Raspberry Pi between us, why not try it. We know others have said it does not work (well) but was still worth a try.
We did not want to create a downloadable image ready to go with scripts to hold your hand. AllStar exported from the SVN, dahdi from asterisk.org and roll your own.
The scripts we built will help you install the required libs to compile
Asterisk and some simple patches to fix some issues with Wheezy and
Raspbian. SSL (res_crypto) and GSM. We also fixed the script that downloads the source for iLBC just to be complete.
The test machine for the project was the first rev Pi 256 MB. Keeping the loaded modules to a minimum, leaves about 64MB of free memory. Audio reports are good Surprising since we are do not have access to Discriminator and Modulator. The one complaint we got was the squelch crash at the end of a user transmission. This is a work in process and I would not put it out at a remote site. For a local simplex node, it seems to work. One of the nodes is running full time on the bench at node 2153.
I'll post a link to the tar of the scripts and patches. It's worth playing with if you have the time to wait for a compile and want to get your hands dirty with AllStar built from scratch.
Oh, and for the heck of it, we call it the PiStar
73, Steve N4IRS and Mike N4IRR.
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"Anything is possible if you don't know what you are talking about."
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