Willis, I have run across two different versions of a factory mod to apply a backup battery to a Mastr II. One has a built in charger and the other uses an external charger.
The stock GE power supply has a bleeder resistor across the output to keep the voltage in check when lightly loaded, and that has to be disconnected in battery service. The relay in the power supply changes the source over to the battery when the AC power fails and disconnect the bleeder at the same time. It would quickly discharge the battery if it were left connected. The filter caps are still in the circuit when the battery is engaged, so there will be no interruption of service when the AC fails. Not even a glitch on the transmitter if it happened to be keyed. Here is a link to a recent backup system I installed on a GE Mastr II repeater. It did not have the built in charger, so an outboard charger is used. http://sbarcnm.org/forum/index.php?topic=102.0 73 - Jim W5ZIT "Willis M. Hagler" <[EMAIL PROTECTED]> wrote: Hello All, I have acquired a UHF Mastr II station in great working order. It's got what appears to be a 65-watt mobile type PA (approx 2" high heatsink that sticks out the back) so someday I'd like to upgrade that to a continuous duty model when I run across one. In the mean time I am wondering how to adapt a battery backup system into this unit. I've got the original 30 amp (I think) GE power supply, where the station gets power from the classic Molex-style connector and the PA gets power through the large fuse on the rear of the unit. What I don't see anywhere back there is any designated place to hook up a battery circuit. I'm pretty sure there are hundreds of these things across the country in amateur service and undoubtedly many of you have made some battery system for this very same setup. If anybody could share how you've worked in a battery backup and some sort of charging system I'd love to hear about it. Thanks all!! Mark Hagler W7WMH Seattle
