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Components and Circuits For discussions about component types, alternatives and availability, circuit configurations and modifications etc. Discussions here should be of a general nature and not about specific sets. |
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30th May 2011, 11:52 am | #1 |
Rest in Peace
Join Date: Mar 2006
Location: N.W. Oxfordshire(Chipping Norton)
Posts: 7,306
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Equivalents to Motorola Transistors with 'in-house' numbers
Apologies if this has been discussed before, but, whilst repairing a 70s Motorola Car radio(which didn't need any of them replacing) I got to thinking
what would be suitable replacements for the types 24B, 25A, & 25B types used in the RF/IF circuits of these MW/LW radios, and for the 54C, 54D, P2U, A4K, & P1V devices used in the audio circuits, the first two being small signal types, whilst the last three are driver and output transistors mounted on a heat-sink. I've never been able to find any data on the Motorola Original transistors, but have made a note in the margin of the circuit diagram that BD133/134 and BD433/434s can replace the o/p transistors. Similarly a DHD800 is specified as the AGC diode, but I've seen 1N4148s fitted from new. Out of curiosity does anyone know where I can find any data for these now long obsolete semiconductors? |
1st Jun 2011, 9:56 am | #2 |
Rest in Peace
Join Date: Feb 2004
Location: Hexham, Northumberland, UK.
Posts: 2,234
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Re: Equivalents to Motorola Transistors with 'in-house' numbers
I used to repair Motorola Communications equipment and they always used in house numbers for semiconductors. Occasionally you were lucky enough to find equipment with standard part numbers on components, and a note was made to use as a future cross reference but the company I worked for bought most of the parts from Motorola as genuine spares using the part numbers from the manuals. We never found any official cross reference lists. They occasionally used abbreviated part numbers shortened to the last five or six digits from the original longer number.
Alan. |
1st Jun 2011, 10:32 am | #3 |
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Join Date: Jun 2003
Location: Oxford, UK
Posts: 27,970
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Re: Equivalents to Motorola Transistors with 'in-house' numbers
Yes, Motorola seem to have used house codes for their semicondictors for many years for no obvious reason. I have a bag of silicon transistors with just a big M and a number which I've never managed to decode. They test like BC168 general purpose types.
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1st Jun 2011, 10:51 am | #4 |
Retired Dormant Member
Join Date: Jun 2010
Location: Co. Limerick, Ireland.
Posts: 1,183
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Re: Equivalents to Motorola Transistors with 'in-house' numbers
Very common on RF PA transistors. Usually from frequency, supply volts, power and package you can figure what the "public" part number would be as RF P.A transistors usually spec for particular band and 12V or 24V separately, rarely more as well as power.
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