In CQ-TV 265, Clive G3GJA details how he got along with a amplifier kits from Bert PE1RKI for 70cm and 2m using Mitsubishi modules. These superb kits are subject to Bert's lead times for delivery.
The same modules form the main element of the Mini-kits UHF amplifier which turns the 10mW from a Portsdown into 11W clean DATV. A Pentium P4 heatsink and fan needs to be found to mount the module and PCB to its surface. The low pass filter kit for 437MHz duty is available from elsewhere on the same website. These typically arrive in 3 weeks.
Use a paper template with a rectangular aperture when applying the horrible heat sink compound. This ensures you get the dimensions for the compound shown in the Mitsubishi application note. You can use a plastic straight spreader to smear the compound then remove the template.
The Nokia TTRX Dolphin amplifiers appear from time to time at rallies and on Ebay. BATC members have modifed these. Other websites that deal with these are e.g.