Steve, May I make a suggestion? I have fiddled with big power 2 meter repeaters for a lot of years and I have a favorite amplifier that I would like you to consider. Many years ago GE made a 250 - 330 watt high-band amplifier for the Mastr Professional series called the 4EF5A1. This amp takes 10 watts of drive and makes 330 watts using a single 4CX250B/R tube, and tunes the 2 meter ham band with no modification; as the range is 144 to 174 MHz. I won't go into the advantages of using tube power, because that is covered in an article I wrote several years ago, link mentioned below. The 4EF5A1 was a current model through the Mastr II years, and in my opinion will still out-do any amateur grade solid-state (and most commercial) amplifier available. The Motorola 1/4K is a good amp, but was not intended to tune the 2 meter ham band, and doesn't provide the level of protection against several operating conditions like the GE EF5 does. There was also a 250 watt model called the 4EF5B1, but I really don't think there were any differences in the two amplifiers; most likely just for FCC licensing and possibly the setting of the Plate over-current relay. I have seen these amplifiers recently at hamfests for a decent price, and I have the complete manuals (for free) on Mastr2 Dot Com. While going down the isles at Dayton this year, I saw Andy - WA3PBD looking at a couple of old 6 foot GE cabinets that had been left behind. He and I looked at one another and in disbelief, opened the cabinets. Both were Mastr Pro high-band units with the 330 watt PA's. We helped one another dismantle the cabinets and each walked away with a complete amplifier for free. I even took the time to get the meter panel! Over the years I have purchased several of these amplifiers from eBay for a few hundred dollars or less. While it's a big project to build a complete stand-alone amplifier, in my opinion it's worth the effort.
Here are some interesting links on the subject: http://www.repeater-builder.com/rbtip/hpa.html http://www.shol.com/kuggie/ahra/hmft.html http://www.shol.com/kuggie/ahra/hmftinfo.html Hope this helps... Kevin Custer stephenucedu wrote: > I am new to the group, and just wanted to know if anyone had a 200-250 watt > amp for sale > for our 2-meter repeater. The core of the system is the Vertex 5000, but its > output is 25 > watts, and after the duplexer, there just isn't enough coverage to match the > receivers that > we use. We had a 100 watt Motarola for years and kept saying that we needed > to increase > the output and improve the transmit antenna/location. Well, that amp went > down, but we > have everything else in place now. There is no size limitation, so a big amp > is fine. The > Motarola 1/4 k amp that was recently posted would have been perfect, but > looks like its > gone. > > Thanks, > > Steve > WA4BVO
