I have still some 1N60 I bought about 15 years ago. They have a green band and no other marking. Iv'e not many left so I ordered some 1N60P from a UK eBay seller not too much more expensive than China, hoping he really was in the UK. They came today via Royal Mail and An Post, so "epartbox" does seem to be shipping from the UK.
They are Vf = 266 mV +/- 9mV and about 18 pF +/- 1pF (precision LC meter that does down to 0.5 pF +/- 0.2pF), but 0 pF on Chinese tester. At least 50V PIV (56 to 65V).
They look like 1N4148, except marked 1N60P in the tiny black print.
They are about Vf =341 mV, +/- 2mV and zero voltage capacitance is about 7.8 pF +/- 0.2pF, less with any reverse voltage, about 6pF on a Chinese tester. PIV is better than 60V (measured parts were 68 to 80V).
Conclusion:
The old green band ones are best for a crystal set or very low level peak detector. They might not be great without selection for a ring diode mixer. Capacitance might be an issue on higher RF frequencies and detectors above 10.7 MHz. The marked 1N60P part is better for anything other than a crystal set or a very low level peak detector at lower frequencies. In practice there might not be much difference on a crystal set or low level detector (about 80mV difference).
The recent purchase with 1N60P on the body that look identical to 1N4148 with body print seem to have a smaller spread of Vf, so may be fine in a ring diode mixer without selection. There is less varicap action, i.e. the capacitor isolated capacitance is only 2pF more than the Chinese tester capacitance (18pF more with green band part) and is a fairly low 8pF with no voltage to less than 6pF reverse biased. There is no measurable spread on capacitance as +/- 0.2pF is less than the repeatable measurements without a jig. With a PIV over 60V and low capacitance they should be fine for an FM Ratio detector. I'll try them on my 21.5 MHz IF.
I'll trace curves sometime and measure reverse leakage. The PIV is too high for that Vf for a Schottky diode. The low Vf types are only 15V to 20V PIV.
It looks an interesting comparison. I presume production techniques have changed greatly over the years so the specifications are maybe unlikely to be as variable? I like to keep an ear the the crystal set scene as, although it's seldom I do much with them, I do have interest. I notice that people still swear by 1N60's but there are many forgeries about. Personally I go Russian as I feel they can be more reliable to form. Many crystal set builders appear to be of a similar opinion.
Tracy
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.
For what it is worth:
[
attachment=19890]
(18-08-2020, 11:42 AM)Mike Watterson Wrote: [ -> ]I have still some 1N60 I bought about 15 years ago. They have a green band and no other marking. Iv'e not many left so I ordered some 1N60P from a UK eBay seller not too much more expensive than China, hoping he really was in the UK. They came today via Royal Mail and An Post, so "epartbox" does seem to be shipping from the UK.
They are Vf = 266 mV +/- 9mV and about 18 pF +/- 1pF (precision LC meter that does down to 0.5 pF +/- 0.2pF), but 0 pF on Chinese tester. At least 50V PIV (56 to 65V).
They look like 1N4148, except marked 1N60P in the tiny black print.
They are about Vf =341 mV, +/- 2mV and zero voltage capacitance is about 7.8 pF +/- 0.2pF, less with any reverse voltage, about 6pF on a Chinese tester. PIV is better than 60V (measured parts were 68 to 80V).
Conclusion:
The old green band ones are best for a crystal set or very low level peak detector. They might not be great without selection for a ring diode mixer. Capacitance might be an issue on higher RF frequencies and detectors above 10.7 MHz. The marked 1N60P part is better for anything other than a crystal set or a very low level peak detector at lower frequencies. In practice there might not be much difference on a crystal set or low level detector (about 80mV difference).
The recent purchase with 1N60P on the body that look identical to 1N4148 with body print seem to have a smaller spread of Vf, so may be fine in a ring diode mixer without selection. There is less varicap action, i.e. the capacitor isolated capacitance is only 2pF more than the Chinese tester capacitance (18pF more with green band part) and is a fairly low 8pF with no voltage to less than 6pF reverse biased. There is no measurable spread on capacitance as +/- 0.2pF is less than the repeatable measurements without a jig. With a PIV over 60V and low capacitance they should be fine for an FM Ratio detector. I'll try them on my 21.5 MHz IF.
I'll trace curves sometime and measure reverse leakage. The PIV is too high for that Vf for a Schottky diode. The low Vf types are only 15V to 20V PIV.
I know what you mean about forgeries but, with the majority of users not really understanding the coding systems used on parts, it is easy for incorrect parts to be supplied, particularly to the home user. For instance, in a simple toy crystal set I bought for fun the diode was Silicon even though the handbook said Germanium. Although I have managed to avoid component problems by buying from reputable dealers the sheer volume of tales from many places, even with diodes, does make me think many are true.
Your point about 'Any design that depends on device selection is poor' is a very valid one. I think that this is maybe one good reason that the Japanese did so well with their methods late last century (thinking of their precision in engine manufacture as much as anything else). I don't think that it will ever really be totally lost though as, taking your comment of the 80mV difference not making much difference in the real world. Not to most people I am sure but it would perhaps make all the difference in a DX crystal set with a distant contact.
Tracy
An interesting datasheet - very few points of comparison. I found another which may be more useful:[
attachment=19891]
And yet another which seems to confuse things? [
attachment=19892]
Tracy
EDIT: Mod tidy up...
They are really the same and the same as my tests.
The weasel aspects are Typical and Max.
Also I don't know what forward current the automagical Chinese tester was using. It's interesting that my 1N60P Vf is closer to the datasheet for the plain 1N60 and that my Green band 1N60 has the 1N60P Vf. And the Capacitances my of 1N60 and 1N60P are also reversed. Both the DEC and Weitron datasheets are similar.
For a crystal radio you want to assume a 4K (2 x 2K earphones) with an RF decoupling cap or 10k (a 10K resistor across a ceramic or crystal earpiece) with the ceramic earpiece as the 3nF to 10nF cap. A peak detector will give sharper tuning as it loads less, needs an extra diode and capacitance. Minimum signal is a little less, but it's twice as loud. Thus the forward current is tiny. I'd want to measure a number of diodes and I'd bet the aerial and earth and Q of tuning coil has more effect. Litz wire on a glass spice jar.
Note my PIV of both diodes is an estimate by a 20 M Ω input DMM on volts across the diode fed by a 400V+ capacitor tester that has 2 M Ω source impedance, so it's non-destructive. I subtracted at least 6V off the lowest rating and there is quite a spread.