tahrens301 wrote: > .....snip..... > > I noticed that there is some silkscreen on the transmitter > interconnect board (in the big hole to the right of the > exciter) that says 12WPA. > > Didn't know whether Mot actually had put a low power amplifier > into the space or not. > > Anybody know? Hi Tim,
Yes, the 12 watt PA was used in UHF Stations in that location. On VHF, the amplifier was usually mounted externally - usually in the form of a mobile heat sink mounted into the rack above the Unified Chassis. The VHF 12 watt PA was commonly used to driver higher level tube-type PA's. The MICOR series is not known for its efficiency, especially when commercial frequency range gear is tuned into the ham band without being properly converted. That being said, there are several things that you can do to improve the power efficiency. I don't believe the exciter itself is terribly inefficient, as it uses an unheated channel element. The tuning of the exciter into the ham band usually results in factory specification performance without modification, the exciter filter and PA are another story. Modification of the exciter filter is usually not difficult, but the PA conversion can be. So, since you only want a small amount of transmitter power, you might want to look into using a Japanese Power Brick for the PA; as they are usually very power efficient. Repeater Builder makes a little circuit board to aide in the use of such a module for this type of purpose. http://www.repeater-builder.com/products/ The receiver can be made to have better power efficiency by removing the B+ from the audio power amplifier. Since these circuits are Class A/B, they draw current all the time. In solar applications I usually place a SPST switch in the B+ lead to the audio power amp so the current can be cut off when it's not in use. There is a bunch of other circuitry that you might also consider eliminating, like any cards that may no longer serve any useful purpose. Most repeaters can be built to deliver the necessities to a controller and the rest of the support circuitry can be gotten rid of. The NHRC Micro is a really good controller choice where power consumption is concerned. The Micro installed in a MICOR allows solid RF technology to be interfaced with a modern controller. http://www.nhrc.net Good luck with the project, Kevin Custer