19-05-2012, 05:31 PM
As with all things it's practise.
Well, I've done the VHF side and things didn't go too badly, I suppose. The first two transistors were dead-short screen to emitter and and had a lesser short to their collectors. The other two seemed fine.
Unfortunately (here it comes!) the leads had got badly mangled and while straightening them one of the bases broke off right at the top.
I've put a BC327 (which work in R200s) in but it's not doing anything: there's no sound at all coming out of either it's own amplifier or my external one. I wasn't expecting it to WORK with the wrong transistor but thought there may be some hiss or oscillation at least. I haven't got any AF114s but should be able to borrow an AF117 from something else. On the external amp it's drawing 10mA on VHF and 5mA on MW and LW.
I'll have a go at the AM side tomorrow with Dr Mark's method and see if I can get that going as if not it implies that the switchery is at fault; I have noticed that the "Quiet Tuning" button doesn't lock down. Should it? I'm also suspicious as there's no crackling when changing wave-band. In the mean-time I'll study the circuit a bit more and try to fathom what does what.
Cheers
Joe
Well, I've done the VHF side and things didn't go too badly, I suppose. The first two transistors were dead-short screen to emitter and and had a lesser short to their collectors. The other two seemed fine.
Unfortunately (here it comes!) the leads had got badly mangled and while straightening them one of the bases broke off right at the top.
I've put a BC327 (which work in R200s) in but it's not doing anything: there's no sound at all coming out of either it's own amplifier or my external one. I wasn't expecting it to WORK with the wrong transistor but thought there may be some hiss or oscillation at least. I haven't got any AF114s but should be able to borrow an AF117 from something else. On the external amp it's drawing 10mA on VHF and 5mA on MW and LW.I'll have a go at the AM side tomorrow with Dr Mark's method and see if I can get that going as if not it implies that the switchery is at fault; I have noticed that the "Quiet Tuning" button doesn't lock down. Should it? I'm also suspicious as there's no crackling when changing wave-band. In the mean-time I'll study the circuit a bit more and try to fathom what does what.
Cheers
Joe
