Ok, the Elmer fully retuned the Mastr2 mid power repeater on Sunday and has it tuned for roughly 26 watts out of the P/A... This is a 40 watt P/A. What will this station typically draw current-wise? Right now it's fed off of a 30 amp supply (major overkill) but we'd like to have a rough idea on amp draw to calculate standby time off of batteries.
Thanks! -AJ, K6LOR On Tue, Feb 3, 2009 at 9:45 AM, AJ <[email protected]> wrote: > Charles: > > Any idea what your current draw was when you had it tuned down to 10 watts? > > I've been doing the alignment directly off of the exciter (250 mw off of > the RCA jack on the drawer) but the power output doesn't match the needs of > the mobile usage. > > Thanks! > > 73s, > AJ, K6LOR > > On Tue, Feb 3, 2009 at 9:22 AM, Ham-Radio <[email protected]>wrote: > >> AJ, >> >> You asked what is the lowest power level for the Mastr2 radio. I had taken >> a 250 Watt base and turned it down to 10 Watts out for testing purposes with >> out generating any spurs. >> >> However, If I remember to documents say to not run the poweer any lower >> than 50% of rated power out. >> >> Remember, you can use only the driver if you need low power out. >> >> Charles Miller >> >> >> ------------------------------ >> *From:* [email protected] [mailto: >> [email protected]] *On Behalf Of *AJ >> *Sent:* Tuesday, February 03, 2009 10:04 AM >> *To:* [email protected] >> *Subject:* Re: [Repeater-Builder] GE Master II Pa decks >> >> With regard to the Intermittent Duty 50 watt Stations, what is the >> lowest these will tune down to without excessive spurs? >> >> I have a Mastr2 VHF station we're looking at placing in our command >> trailer for temporary operations - AC power most of the time, but would like >> to have it draw as little power as possible (within reason) for times when >> working on battery power only. 250 mw off the exciter just isn't enough, 65 >> watts out of the P/A is just too much. >> >> >> 73s, >> >> AJ, K6LOR/R >> 147.080+ >> 444.750+ >> >> On Mon, Feb 2, 2009 at 6:13 PM, Nate Duehr <[email protected]> wrote: >> >>> An isolator with appropriate harmonic filtering AFTER it (they create >>> harmonics, which are not friendly to your neighbors), presents a nice >>> solid >>> non-reactive 50 ohm load to the transmitter. It doesn't matter if it's a >>> GE >>> MASTR II PA, or someone elses. Many Motorola PA's have the isolator built >>> in, for example. >>> >>> The GE PA likes a 50 ohm load or it tends to do squirrelly things, like >>> die. >>> You can get this by proper choice of QUALITY products for your >>> filtering/feedline/antenna system, or you can use an isolator, or you can >>> have the "belt and suspenders" mentality and always run an isolator on >>> the >>> output of the PA. Another good reason to do this at high RF commercial >>> sites is that the PA (depending on how you may have modified it) has >>> transistors in the final section that are "always on", thus... mixing can >>> occur in the PA if RF from the outside world can get down INTO the PA >>> from >>> elsewhere. Also not a nice thing for your neighbors. >>> >>> The final "benefit" to a properly sized dummy load on your isolator is >>> that >>> the antenna can literally fall off the tower, and the PA will still be >>> driving into a solid 50 ohm dummy load. As long as that load is the >>> correct >>> size for your PA's power level, no damage to the PA will occur, even >>> though >>> your antenna is gone. >>> >>> Some late-model MASTR II PA's have built in Z-matchers on their output >>> Low-Pass Filter board on the right lower side. These have to be adjusted >>> correctly per the manual any time a new PA is installed on a new antenna >>> system, or anything changes in the antenna system. Older PA's do not have >>> this feature, but an off-board Z-matcher can be added in lieu of an >>> isolator >>> if all you're concerned about is matching the source (PA) to the load >>> (antenna system). >>> >>> The GE PA comes in different sizes for different power level needs. The >>> VHF >>> 100W (original with four final driver transistors) was known to get >>> spurious >>> and throw stuff up and down the band for various reasons. The newer >>> three-final-transistor PA's (the most commonly seen) are less prone to do >>> this, but can also become RF noisemakers if turned down too much. No >>> MASTR >>> II tech I know of will recommend turning any MASTR II PA any further down >>> than roughly 2/3's its maximum rated power output, ESPECIALLY not without >>> looking at it on a spectrum analyzer to make sure it's not spurring. When >>> they go spurious, which is rare enough people get away with turning the >>> PA's >>> down more than 2/3's, they also typically overheat drastically and >>> they'll >>> destroy themselves relatively quickly. >>> >>> If you need less power than 50W it's highly recommended to remove stages >>> of >>> the PA to get to the lower power level you need, bypassing them >>> completely, >>> or moving to a lower power/lower-duty-cycle PA in the model line. >>> >>> Done right, even after 20 years of commercial service, the VHF MASTR II >>> PA >>> will happily sit there and put out 85W all day long, without batting an >>> eyelash. Many will still do a strong 110W and never care, either. It's >>> just a little "easier" on the gear to run the power back just a little >>> bit. >>> The difference (in dB) between 85W and 110W often isn't significant, >>> depending on your area you're wanting to cover. >>> >>> Why are you wanting to turn your MASTR II back so far? After duplexer >>> losses, you're down to roughly 20W if you're putting 45W into a duplexer >>> (if >>> you're running split antenna, with no duplexer and vertical separation, >>> nevermind -- but I doubt you are), and 20W doesn't "balance" well with >>> 50W >>> mobiles. If you're trying to balance for HT coverage only, I could see it >>> maybe... >>> >>> My personal rule for the MASTR II PA's is: Set 'em to 85W and forget 'em. >>> Put an isolator on for ALL of the good reasons for an isolator, filter it >>> properly, and forget about it. The vast majority of them will run for 10 >>> or >>> more years without touching them again after doing that. >>> >>> Look carefully at the Repeater-Builder company specifications -- you may >>> be >>> looking at a MASTR II *MOBILE* rig converted into a repeater. That's NOT >>> a >>> MASTR II Repeater PA. They're de-rating the PA to save it from >>> overheating >>> and dying, as it's not rated for 100% continuous duty at full power in >>> the >>> mobile rig with the small heatsink. The MASTR II REPEATER PA is a giant >>> heavy thing with plenty of heatsink fins, 19" wide and multiple RU tall, >>> that is EIA rated to do continuous-duty cycle at 110W for at least 24 >>> hours. >>> >>> Nate WY0X >>> >>> -----Original Message----- >>> From: [email protected]<Repeater-Builder%40yahoogroups.com> >>> [mailto:[email protected]<Repeater-Builder%40yahoogroups.com>] >>> On Behalf Of Randy >>> Sent: Sunday, February 01, 2009 8:24 AM >>> To: [email protected]<Repeater-Builder%40yahoogroups.com> >>> Subject: [Repeater-Builder] GE Master II Pa decks >>> >>> Hi group whats the deal with the GE Master II PA decks needing to use a >>> ferrite isolator with a 50 ohm dummy load and a low pass filter between >>> the PA and the High Q duplexer. Is this something that most do with >>> the 75 and 100 w Pa's We just replaced one in a Master II Mobile radio >>> which lasted for years with no issues. After installing the PA and >>> doing a tune up the Radio did about 80 watts we set it to 45 watts I >>> was also told that was not a good thing to do so whats the story on the >>> PA. I seen where Repeater Builder the Company talks about the 75 or 100 >>> watt PA's in there web site only bening good set to 45 watts or so >>> anyway so I assume they are setting theres at that level when they do a >>> Duplex conversion ect making the radio into a repeater. I have read the >>> information on the website about this but would like some user comments >>> as well. Also where would one get the needed parts ect to do this Mod. >>> >>> Randy >>> >>> ------------------------------------ >>> >>> Yahoo! Groups Links >>> >>> >> >> > >
