[Techman]

Just catching up with this thread.

There's not much that I can really add.

The big brute which is Q55 from memory is something like a 150 volt 25 amp (or thereabouts) transistor, also used in audio amplifier applications and was the part that had failed on the radio that I had to repair last year. The circuit around this area, including that actual transistor type seems to have undergone considerable changes during production, and it makes you wonder what actually causes these failures and whether there's some oscillation or stray RF somewhere that's getting in where it shouldn't, but only sometimes and under certain conditions. Mike said something about the power control not turning the power all the way down like he thought it should - I can't remember what sort of range this control had on the set that I had here, other than it worked and I remember having it set to an output power that a 5-7 amp test power supply would happily run it at. I remember talking to the radio's owner on it before taking it back to him and we tried it on both FM and SSB - AM was not checked, but I think I possibly did a quick 'monitor' type check with another radio in the same room just to prove it was also working.

As for the Q17/18 transistors - I also can't seem to see them on the diagram, so perhaps another more recent change during production. I can't see that shorted turns on L27 will have any effect in this instance, but I well remember the inductor with just a few turns that used to overheat and develop shorted turns on the old '059' chassis, killing the RF output with lots of heat still - I'm actually working on two home base models of that chassis when I get time, both having had multiple issues, as you can imagine - perhaps a story for another thread.