Interface notes are a little way down the page - this first part is just me rambling about WHY I did this.
Why run NBEMS on an LCR (Little Chinese Radio)?I participated in the Lindon City Drill Down for Safety preparedness exercise earlier this month. We had one ham radio operator in the EOC (Emergency Operations Center) and 3 area operators. Each area had neighborhoods reporting with scenarios that we were required to relay to the city EOC as they came in from runners or over the neighborhood radio nets (some of which were using FRS radios). This was accomplished admirably in the time allotted for the exercise (just over 60 minutes). I think we relayed close to 30 scenarios and a few other things as well. Had there been more scenarios, or other traffic (health & welfare, etc.) that needed to be passed over the net from the areas to the EOC, there would not have been enough time to get it done. As it was, the radio operator in the EOC was fully engaged in receiving, transcribing, and disseminating the scenario information to the participants at the city.
Creating the Interface
|I took advantage of a couple of existing solder pads for the resistor and tried to put the capacitor in a place where it would not contact other stuff. The wires from the cable were very tiny, but soldered just fine without doing anything special.|
|A view of the isolation transformers on the other side of the PCB.|
|The finished unit from the bottom|
Although work and home are only 4 miles apart, there are some good sized hills in between. Also, work is in a building that is really good at blocking radio waves. At home I have a Comet GP-6 clone hooked to a Kenwood G-707A and the SignaLink interface I mentioned earlier. From inside my building at work, I can't hear the home radio consistently on 2 meters even at 50 watts especially from where my desk is located (bottom floor on the opposite side from my home). From outside in the parking lot, my truck's radio (a Yaesu FT-8900R and a Comet SSB-5) can talk to home with both ends running just 5 watts. If I set the rig in the truck to cross-band mode, I can use the HT inside the building on 70cm at low power to reach the truck and from there on 2 meters to the house. This works great so far.
All in all, I'm excited about the possibilities for using NBEMS along with normal voice operations for emergency situations. I believe it has more immediate value than HSMM or BBHN, which I have also been playing with, so I am shifting my focus for a time to learn and do more with digital over VHF/UHF. As always, there's plenty more to do (setting up NBEMS on my Raspberry Pi in my trailer for example).