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ME/MA UK 1970's transistors?
Hi all,
I'm restoring a couple of 1970's wooden case acoustic coupler, both made in the UK. I haven't find the slightest bit of information about both of them, just some pictures on the net. One of them is the DCD model AC.350.OM (where probably OM stands for Originate, as it doesn't have any Orig/Answ switch). Now, I'm checking most parts (it's made on 6 PCBs, plus some chassis-mounted components) for obvious problem, like diode/BJT junctions, carbon composition resistors values, electrolytic ESR/shorts etc. All transistor have MAxxxx or MExxxx codes, they really look like BCxxx transistors from the early 1970's, one of the most common ones is ME4101. By the way, the ICs have 1972-1974 date codes, so this unit was probably manufactured in 1974. My first question is: does anyone have a cross reference for these MA/ME transistors? Are those a kind of military markings? Second question: almost all ME4101 have a junction voltage drop around 0.8V but one of them shows a bit more than 1V drop on both BE and BC junctions (it's NPN). Can I assume this one must be bad? Any other hint and information is welcome. Thanks Frank IZ8DWF |
ME/MA UK 1970's transistors?
On Saturday, 17 November 2018 20:44:14 UTC, wrote:
Hi all, I'm restoring a couple of 1970's wooden case acoustic coupler, both made in the UK. I haven't find the slightest bit of information about both of them, just some pictures on the net. One of them is the DCD model AC.350.OM (where probably OM stands for Originate, as it doesn't have any Orig/Answ switch). Now, I'm checking most parts (it's made on 6 PCBs, plus some chassis-mounted components) for obvious problem, like diode/BJT junctions, carbon composition resistors values, electrolytic ESR/shorts etc. All transistor have MAxxxx or MExxxx codes, they really look like BCxxx transistors from the early 1970's, one of the most common ones is ME4101. By the way, the ICs have 1972-1974 date codes, so this unit was probably manufactured in 1974. My first question is: does anyone have a cross reference for these MA/ME transistors? Are those a kind of military markings? Second question: almost all ME4101 have a junction voltage drop around 0.8V but one of them shows a bit more than 1V drop on both BE and BC junctions (it's NPN). Can I assume this one must be bad? Any other hint and information is welcome. Thanks Frank IZ8DWF 0.8v V_be is odd. Something isn't right there. NT |
ME/MA UK 1970's transistors?
On Saturday, 17 November 2018 20:44:14 UTC, wrote:
Hi all, I'm restoring a couple of 1970's wooden case acoustic coupler, both made in the UK. I haven't find the slightest bit of information about both of them, just some pictures on the net. One of them is the DCD model AC.350.OM (where probably OM stands for Originate, as it doesn't have any Orig/Answ switch). Now, I'm checking most parts (it's made on 6 PCBs, plus some chassis-mounted components) for obvious problem, like diode/BJT junctions, carbon composition resistors values, electrolytic ESR/shorts etc. All transistor have MAxxxx or MExxxx codes, they really look like BCxxx transistors from the early 1970's, one of the most common ones is ME4101. By the way, the ICs have 1972-1974 date codes, so this unit was probably manufactured in 1974. My first question is: does anyone have a cross reference for these MA/ME transistors? Are those a kind of military markings? Second question: almost all ME4101 have a junction voltage drop around 0.8V but one of them shows a bit more than 1V drop on both BE and BC junctions (it's NPN). Can I assume this one must be bad? Any other hint and information is welcome. Thanks Frank IZ8DWF http://pdf1.alldatasheet.com/datashe...CS/ME4101.html NT |
ME/MA UK 1970's transistors?
wrote:
I'm restoring a couple of 1970's wooden case acoustic coupler, both made in the UK. I haven't find the slightest bit of information about both of them, just some pictures on the net. One of them is the DCD model AC.350.OM (where probably OM stands for Originate, as it doesn't have any Orig/Answ switch). Now, I'm checking most parts (it's made on 6 PCBs, plus some chassis-mounted components) for obvious problem, like diode/BJT junctions, carbon composition resistors values, electrolytic ESR/shorts etc. All transistor have MAxxxx or MExxxx codes, they really look like BCxxx transistors from the early 1970's, one of the most common ones is ME4101. By the way, the ICs have 1972-1974 date codes, so this unit was probably manufactured in 1974. My first question is: does anyone have a cross reference for these MA/ME transistors? Are those a kind of military markings? Second question: almost all ME4101 have a junction voltage drop around 0.8V but one of them shows a bit more than 1V drop on both BE and BC junctions (it's NPN). Can I assume this one must be bad? Any other hint and information is welcome. ** ME4101 etc devices were made by " Micro Electronics" of the USA - Silicon Valley address. http://www.microelect.com/ Made a lot of types in TO106 package - shiny, glob tops and gold plated leads. Very neat looking. ..... Phil |
ME/MA UK 1970's transistors?
On Sunday, November 18, 2018 at 5:14:51 AM UTC-5, Phil Allison wrote:
wrote: I'm restoring a couple of 1970's wooden case acoustic coupler, both made in the UK. I haven't find the slightest bit of information about both of them, just some pictures on the net. One of them is the DCD model AC.350.OM (where probably OM stands for Originate, as it doesn't have any Orig/Answ switch). Now, I'm checking most parts (it's made on 6 PCBs, plus some chassis-mounted components) for obvious problem, like diode/BJT junctions, carbon composition resistors values, electrolytic ESR/shorts etc. All transistor have MAxxxx or MExxxx codes, they really look like BCxxx transistors from the early 1970's, one of the most common ones is ME4101. By the way, the ICs have 1972-1974 date codes, so this unit was probably manufactured in 1974. My first question is: does anyone have a cross reference for these MA/ME transistors? Are those a kind of military markings? Second question: almost all ME4101 have a junction voltage drop around 0.8V but one of them shows a bit more than 1V drop on both BE and BC junctions (it's NPN). Can I assume this one must be bad? Any other hint and information is welcome. ** ME4101 etc devices were made by " Micro Electronics" of the USA - Silicon Valley address. http://www.microelect.com/ Made a lot of types in TO106 package - shiny, glob tops and gold plated leads. Very neat looking. .... Phil You got me curious. Here's a link to a picture. I remember seeing similar transistors years ago in Zenith TVs. https://www.radiomuseum.org/images/t...n/me4101_1.jpg |
ME/MA UK 1970's transistors?
Got a bunch in my vintage (70s) AR tuner, receiver & integrated amp (Made by Fairchild per the service manual). I have had to do some pretty substantial rebuilding over the years, but never to those transistors.
Also a few of this type: http://www.gpecsrl.net/img_componenti19/19727.jpg made by Motorola. Peter Wieck Melrose Park, PA |
ME/MA UK 1970's transistors?
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ME/MA UK 1970's transistors?
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ME/MA UK 1970's transistors?
Look165 wrote:
With such aVBE, they surely are Ge transistors, not Si. They are all Si transistors. Ge have Vbe around 0.3 to 0.4V, I have quite a few devices with Ge transistors. Frank |
ME/MA UK 1970's transistors?
On Friday, 23 November 2018 08:28:18 UTC, wrote:
Look165 wrote: With such aVBE, they surely are Ge transistors, not Si. They are all Si transistors. Ge have Vbe around 0.3 to 0.4V, I have quite a few devices with Ge transistors. Frank I can't imagine what Si tr would have 0.8v V_be or why. Do you know? Geraniums start much lower of course, but also rise higher quickly as current increases. 0.8v on a Ge junction is no cause for surprise. The ME tr you mentioned is a Si device, so I'm puzzled by its V_be. NT |
ME/MA UK 1970's transistors?
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