Albert, Yes, you must tune the amplifier for the narrow range of frequencies that you will be using. The N1274A amplifier was used with MT500 and MX300 Converta-Com Consoles to boost the output of the Handie-Talkie in mobile service. The unit has a sensor to detect the transmit signal and switch the amplifier into the circuit, The manual which covers this specific amplifier is 6881020C90- which, unfortunately, is NLA from Motorola Parts.
73, Eric Lemmon WB6FLY -----Original Message----- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Albert Sent: Tuesday, March 10, 2009 11:04 PM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Help with N1274A VHF amplifier please I have very cheaply acquired a Motorola N1274A amplifier and would like to use it on 2 meters. My first question, is, since this amplifier was originally designed for 150-174MHz do I need to do any retuning. I assume the answer would be yes. On the board, on the far left and the far right I see two components that appear to be tuning capacitors. They are marked Johanson 9612. (Looking them up on the net confirmed they were tuning caps) Are these what I need to adjust? If so, what is the procedure? Tune for max power? Min SWR? Any assistance would be appreciated. Also, what tool is used for this? I kind of looks like a tiny hex head, but I haven't looked at it under a magnifier yet. Secondly, I was wondering if anyone has a schematic for the amplifier. I looked on the net but turned up nothing. There is one component inside the amplifier that appears what "used to be" a capacitor. It obviously suffered a catastrophic failure and the magic smoke came out quite rapidly. It is located on the board next to a large 1 ohm power resistor. I obviously need to replace this component and could possibly need to replace others. Again, any schematic or parts list info anyone could share with me would be greatly appreciated. Thanks Albert
