We have a couple of the "mobile sticking out the back" PA's that we will look at.
We'll find the best exciter/PA combination that gives the best efficency. So the original question was answered, the power control pot can be converted to a dual level pot, but at the expense of efficency. It's never as easy as it looks. Thanks to all (once again). Dwayne Kincaid WD8OYG > > GE made a number of PAs for the MII all to be driven by the exciter. I think the lowest for normal mobiles was 35 watts. Also the Exec II PAs will work. > > A 35 W set at 35 W draws about 7 Amps and at 20 will drop to 4 Amp. > > 73, ron, n9ee/r > > > > >From: Nate Duehr <[EMAIL PROTECTED]> > >Date: 2007/10/17 Wed PM 07:24:39 CDT > >To: Repeater-Builder@yahoogroups.com > >Subject: Re: [Repeater-Builder] Reducing power out when on battery backup. > > > > > > >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 > > > > > > > Ron Wright, N9EE > 727-376-6575 > MICRO COMPUTER CONCEPTS > Owner 146.64 repeater Tampa Bay, FL > No tone, all are welcome. >
