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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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Old 25th Mar 2010, 10:52 am   #1
'LIVEWIRE?'
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Question Transistors used in 1970s Motorola car Radios

These have type nos. not found in any data book of which I know-the RF & IF devices are types 25A, 25B, 24A, the output transistors being A4K & P2U,etc., these latter being of a case type I've not come across elsewhere.
I'd be interested to know if anyone knows anything about these, or any source of data for comparison purposes. Back in the 70s I was repair engineer for a Motorola Dealer, and we used to get the pukka types from them. Now I know that the RF/IF types can be replaced with the likes of BF548s, and the output devices with BD131/132 or similar, but would still like to have a bit more info. on the originals, if possible
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Old 25th Mar 2010, 12:43 pm   #2
paulsherwin
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Default Re: Transistors used in 1970s Motorola car Radios

Presumably these are house codes. Motorola seem to have been very keen on these. I have a bag of BC168 class transistors with some meaningless Motorola house code on them.

As you say, you can probably sub functionally equivalent types easily enough, selecting them on the basis of their position in the circuit. It's unusual for 70s silicon transistors to fail en masse though, as I'm sure you're aware.

Paul
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Old 25th Mar 2010, 1:55 pm   #3
kalee20
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Default Re: Transistors used in 1970s Motorola car Radios

Unless, that is, you connect a positive-earth car radio to a negative-earth car, or vice versa!
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Old 27th Mar 2010, 2:26 pm   #4
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Default Re: Transistors used in 1970s Motorola car Radios

I thought that was the case, Paul, and I'm sure I can use substitutes as outlined in my post#1. The A4k & P2U devices have a mounting tab, but aren't any of the usual case types, but that shouldn't matter.
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Old 27th Mar 2010, 2:54 pm   #5
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Default Re: Transistors used in 1970s Motorola car Radios

I used to work for a service shop which specialized in Delco & Motorola car radios.
After starting-up my own business I also handled the Motorola line. (70's) I still have old
archived info, the only question would be where I put it. I'll see what I can find & then
conact you again.

Andrzej
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Old 27th Mar 2010, 7:59 pm   #6
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Default Re: Transistors used in 1970s Motorola car Radios

Thanks, Andrzej. I don't remember ever seeing data sheets for any of the transistors I mentioned, even back in the 1970s. Were the same types used by Motorola in the USA?
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