stephenucedu wrote: > Does anyone have any experience with the TPL 250 watt 2-meter amps for > repeater use? > (bugs, reliability, operating manual/schematic availability).
Off the main topic reply: Many folks don't realize this..... Many of the modern 4 cavity type duplexer designed for 2M operation barely make enough isolation to properly duplex a 50 - 100 watt solid-state repeater, and it can be difficult to make the repeater work without receiver desensitization. Going to 250 watts (with solid-state power) is even worse unless some care is expressed. By using a GE MASTR II PLL exciter and IPA, about 22 dB less side-band noise is created, thus allowing 250 watts of power to be used with a typical 4 cavity duplexer. Of course, a better 6 cavity model will work, but will have more insertion loss in both directions. (I hate going to the expense and trouble to add 6 or 7 dB of transmitter power just to make an additional dB or so go up in added heat in the duplexer.) One other thing to do is use tube-type power amplification (my favorite). The GE 4EF5A1 is a wonderful long-lasting solution. I have seen a few on eBay lately for a good price. This amplifier can be used on any 10 watt driver (Motorola, GE, Kenwood, ICOM, etc.) and 4 cavity duplexer. Less RF power goes up as heat and you can even use a preamp on your receiver without side-band noise blowing it away. I have no knowledge of the amplifier Steve is considering, but he may want to consider the above if he gets one, and presently has a multiplier type transmitter. BTW: (relevant comment on another recent thread) Use RG-214 Mil-Spec, RG-400, and the like interconnection cables, not 9913, or LMR-400. I can't begin to tell you how many folks have inquired (to me personally) for repeater noise help and the replacing these types of cables fixed the problem, totally! Kevin Custer Repeater Builder
