At 06:14 AM 04/15/09, you wrote: >Mike Morris WA6ILQ wrote: > > > The high power 74MST was a 4 freq UHF MOTRAN > > (and used a 28volt PA deck run by a 12-to-28 transistorized > > switching power supply in the center section) along with > > the receive F3 and F4 channel elements. > >I don't remember ever seeing those! I saw lots of U74MST's >that were rated 90W, and had a ceramic tube final.
I only saw one, and it had an SP model number and a ditto- printed manual. >Also most had relays that switched tuning in the PA so that >it would do talkaround. There were Motracs that solenoid based tuning systems. >When you went to F2, for instance, the relay pulled in, >and changed the tuning of the PA. >Got to be a nightmare once they got to be 10-15 years old... Oh yeah.... I had one, and in the beginning it was neat, but it got to be a major PITA. I ended up dumping the wide spaced radio and going back to two individual full duplex UHF MHT Motracs. The MHTs had a totally passive front end all the way to the first mixer and were easy to duplex - cut two wires, add a jumper and you are done. If the repeater had enough ERP you could duplex across the antenna relay, if not, you had to unplug the coax jumper that plugged into the receiver casting and plug in a separate receiver antenna... At one point my Ford Falcon station wagon had a low band 4F LHT on 6m, a high band MHT (6F or 8F, I forget) , and two UHF MHTs, plus a couple of other radios in it. The UHF MHTs and the police scanner shared a single 18" receive antenna. And the straight 6 and front drum brakes got replaced with a 302 V8 and disks off a wrecked and rolled Mustang... but that was another project... Mike WA6ILQ
