On Oct 16, 2007, at 10:10 PM, ldgelectronics wrote: > It looks like the seperate small amp will be the best solution in > terms of maximum battery life. I checked another repeater on the > bench tonight and found pretty much the same thing as Ron mentioned. > You can lower the RF power, but the efficency gets worse.
After having read along the entire thread, I think you're probably right -- another PA that's more efficient at the lower power setting will work best for you, at least to get the project going. The trick is finding PA's with 250mW inputs, which is pretty low for most "HT" type PA's, etc. (It's not shown on their website, but Henry will modify their PA's for a 250mW input, according to a recent e-mail exchange I had with them about a Henry that the club owns but hasn't been useful to us, since we went to the MASTR II Station/Repeaters.) Anyway, to add more ideas -- I just thought I'd mention that there is a lower-power VHF stock MASTR II PA that only has the driver board, minus the final board, that has a coax jumper across to the low-pass filter board. Once in a while you see them on eBay. I believe it's 40W continuous-duty, but I'd have to go check the LBI's. There are also the "mobile sticking out the back" style of "station" PA's that are just the back end of a mobile sticking through a mounting plate that fits where the stock GE PA goes. They're not "officially" rated for continuous-duty, but could be turned down to a fairly low power if they had the same "modification" to remove the final board, and/or some came that way. (Again, I'd have to go pull up the LBI's for those to see how many different "varieties" GE made.) Any of those other stock lower-power GE PA's could be switched in and out by switching the exciter's output between the two PA's using a RF- rated relay, etc. Just another thing to think about... if you can find them. I have only run across one of the low-power VHF continuous-duty PA's, and it came from a remote-base setup for the railroad in Canada, apparently -- judging by the fact that it has a GE Canada badge, and I bought it from a Canadian. (GRIN) It only had two or three sets of heatsink fins, versus the usual full compliment across the back of the PA. It'd be easy to spot in photos in an eBay auction, etc. Might be something to keep an eye out for. -- Nate Duehr, WY0X
