Earlier this year, at a rocket launch, I saw the need for a portable repeater. The handheld radios (HT) just couldn't reach out. It seems that the playa at the Black Rock Desert would absorb the RF energy instead of reflecting it. Many of the rockets were landing about 3 miles down range. Normally a handheld radio would easily communicate over this distance. On this occasion I was getting less than a mile with my HT and 3 watts. I thought a repeater placed on one of the surrounding hills would work really well. On the drive home from the launch, I concluded that the easiest type of portable repeater would the a simplex repeater. I chose the NHRC-2 Repeater Controller for the brains of my portable repeater. One of the features of this controller is that it can operate as simplex repeater. One of the requirements of this repeater controller is that it needs access to the squelch circuitry of the radio. I decided that the packet data port on a radio would probably do the trick. I look at my packet radio station (a Kenwood TM-251A and a Kantronics KPC3) and saw the TM-251A data port provides the signals needed (audio in, audio out, PTT, and squelch). I really didn't want to use the radio from my packet station so I looked around on the internet to see if I could find another TM-251A. The newer kenwood 2 meter radio TM-261 doesn't include a data port. I posted a want-ad and didn't have any luck in finding another TM-251A. I received a flyer from Amateur Electronic Supply featuring a sale on the Yaesu FT-1500M. I bought the Yaesu and it turned out to have the data port with all the signals the NHRC-2 needed. I used the Yaesu data cable to connect the NHRC-2 Repeater Controller to the radio, thus allowing the radio to function normally with the MIC if needed. I connected the repeater audio out to the 1200 baud input. This seemed to give adequate sound quality.
Here's the finished project
A look inside
Here are some pictures of the repeater deployed on the edge of the Black Rock Desert
Here are more pictures taken by Ian.
[Info & pictures about HT battery.]
I acquired some new 12v 7Ahr sealed lead-acid batteries from a 5Kw rack mount UPS. They fit nicely in an orange utility box (like the one used for the simplex repeater). The box is a 5601 series manufactured by Action Products. I purchased the utility box from Overton's, item number 25960. Pictures and more info coming soon
Section updated: 13Feb2009
[Info & pictures about portable digi.]
[Info & pictures about of the mobile radio case and setup.]
[Info & pictures about project 7.]
Section updated: 19Jan2010
[Info & pictures about project #8.]