18-08-2020, 01:37 PM
(This post was last modified: 18-08-2020, 01:40 PM by Mike Watterson.)
The Russians were still developing and producing Germanium parts as well as Rod Pentodes when most companies in the West were only doing Silicon.
I'm sceptical of the idea of 1N60 forgeries as it's too low value part. There are just different parts made at different times and places that might have the same designation, or sold as a part as they are sufficiently similar for most applications.
The original 1N60 and 1N34 of 1946 are quite different.
I'm sure from my own lab tests about 12 years ago that the most sensitive detector without an amplifier is the 1N60. An 80mV won't make much difference in the real world.
Also some parts like FETs the newer ones may have a lower Vt, which is normally thought as a good thing. They will fry in a poorly designed circuit that assumes a high Vt, or that needs adjustment that's not obvious.
Increasing PIV and reducing capacitance and part variation is good. The BC107, BC108 and BC109 may have originally just been the same production, but tested to grade them. Certainly true of a, b, c suffix gain. You see the same with early triodes and pentodes. Often they were colour coded with a table of bias battery settings. Later in the 1930s valve making became highly automated and there was less variation. Even so the gm variation on 1960s valves and 21st Century transistor gain is quite large.
Any design that depends on device selection is poor. The circuit has to either cope with variation or have feedback or adjustment. It's inherent in ICs that the transistors even side by side on the chip don't match, hence op-amp offsets. Where this is an issue there may be two extra pins. Or devices may be selected on test or even laser trimmed in a test circuit before encapsulation.
I'm sceptical of the idea of 1N60 forgeries as it's too low value part. There are just different parts made at different times and places that might have the same designation, or sold as a part as they are sufficiently similar for most applications.
The original 1N60 and 1N34 of 1946 are quite different.
I'm sure from my own lab tests about 12 years ago that the most sensitive detector without an amplifier is the 1N60. An 80mV won't make much difference in the real world.
Also some parts like FETs the newer ones may have a lower Vt, which is normally thought as a good thing. They will fry in a poorly designed circuit that assumes a high Vt, or that needs adjustment that's not obvious.
Increasing PIV and reducing capacitance and part variation is good. The BC107, BC108 and BC109 may have originally just been the same production, but tested to grade them. Certainly true of a, b, c suffix gain. You see the same with early triodes and pentodes. Often they were colour coded with a table of bias battery settings. Later in the 1930s valve making became highly automated and there was less variation. Even so the gm variation on 1960s valves and 21st Century transistor gain is quite large.
Any design that depends on device selection is poor. The circuit has to either cope with variation or have feedback or adjustment. It's inherent in ICs that the transistors even side by side on the chip don't match, hence op-amp offsets. Where this is an issue there may be two extra pins. Or devices may be selected on test or even laser trimmed in a test circuit before encapsulation.
