27-06-2017, 01:00 PM
I've not heard them called "spotters" but this kind of spot frequency generator was commonplace before the days of synthesised tuning. They provided a grid of accuarate frequencies to calibrate other equipment.
Why not Ge transistors? Basically because they're pretty hopeless. They are leaky, highly temperature sensitive, useless at high temperatures and generally don't work very well. Silicon wins hands down on everything except saturation voltage and possibly performance at extremely low temperatures. The latter is only of interest below perhaps -50C. Saturation voltage issues have been dealt with by using MOSFETS which can have extremely low on-resistance and no saturation voltage effects.
What if makers had put lots of development into Ge? I don't know, but Ge remains a relatively rare and expensive element while Si is abundant and cheap.
There are a few specialised and exotic Ge devices still made. They use a mixture of Ge and Si in the same device.
There's nothing fiddly or frail about Si devices such as BC548 in TO92 plastic packages. Dirt cheap, work well in loads of circuits.
As soon as you get much beyond very simple circuits, such as those found in domestic radios and TVs, hand wiring is a nightmare. Agreed some PCBs are badly designed or cheaply made but there's no sensible alternative once you get to a certain complexity.
Why not Ge transistors? Basically because they're pretty hopeless. They are leaky, highly temperature sensitive, useless at high temperatures and generally don't work very well. Silicon wins hands down on everything except saturation voltage and possibly performance at extremely low temperatures. The latter is only of interest below perhaps -50C. Saturation voltage issues have been dealt with by using MOSFETS which can have extremely low on-resistance and no saturation voltage effects.
What if makers had put lots of development into Ge? I don't know, but Ge remains a relatively rare and expensive element while Si is abundant and cheap.
There are a few specialised and exotic Ge devices still made. They use a mixture of Ge and Si in the same device.
There's nothing fiddly or frail about Si devices such as BC548 in TO92 plastic packages. Dirt cheap, work well in loads of circuits.
As soon as you get much beyond very simple circuits, such as those found in domestic radios and TVs, hand wiring is a nightmare. Agreed some PCBs are badly designed or cheaply made but there's no sensible alternative once you get to a certain complexity.
www.borinsky.co.uk Jeffrey Borinsky www.becg.tv
