14-02-2013, 10:43 PM
Hi Mark,
The AF139 was the only Germanium one I've got apart from some ACXXX.
I'll check out the decoupling, the weird thing is that moving the twisted speaker leads affects the instability but decoupling them makes no difference. The instability occurs when a signal on MW is slightly off tune, and as I said before with the other transistor this was just apparent. All the earth/chassis connections appear OK so probably it's down to some decoupling cap somewhere as you said. I 'll get my old scope out tomorrow and start digging.
BTW any ideas about using an external PSU without making any holes etc, (Thought about some thick film or thin ribbon cable but It wouldn't be very reliable)
BRs
Mike
The AF139 was the only Germanium one I've got apart from some ACXXX.
I'll check out the decoupling, the weird thing is that moving the twisted speaker leads affects the instability but decoupling them makes no difference. The instability occurs when a signal on MW is slightly off tune, and as I said before with the other transistor this was just apparent. All the earth/chassis connections appear OK so probably it's down to some decoupling cap somewhere as you said. I 'll get my old scope out tomorrow and start digging.
BTW any ideas about using an external PSU without making any holes etc, (Thought about some thick film or thin ribbon cable but It wouldn't be very reliable)
BRs
Mike
