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49MHz motorola finals

B

brandon7861

Loose Wire
Nov 28, 2018
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I have a bunch of old motorola radios (I assume some are 100w at least due to the huge heat sync and big MRF's). I don't use 6m so I am thinking of either parting them out or building an amp or two out of them. Without digging in the shed to look at the part numbers, does anyone know if those 49MHz finals are good for use in 11m amps or are they specifically designed for 49MHz?

Thanks!
 

brandon7861 said:
I have a bunch of old motorola radios (I assume some are 100w at least due to the huge heat sync and big MRF's). I don't use 6m so I am thinking of either parting them out or building an amp or two out of them. Without digging in the shed to look at the part numbers, does anyone know if those 49MHz finals are good for use in 11m amps or are they specifically designed for 49MHz?

Thanks!
Click to expand...
Any VHF band transistor I have ever uses has always worked on 11m as well. In fact it should actually provide a bit higher gain and output. IE The SD1446 is rated for VHF-Lo band for 70 watts. It will reliably put out 100-125 watts pep on 11m.
 
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brandon7861 said:
I have a bunch of old motorola radios (I assume some are 100w at least due to the huge heat sync and big MRF's). I don't use 6m so I am thinking of either parting them out or building an amp or two out of them. Without digging in the shed to look at the part numbers, does anyone know if those 49MHz finals are good for use in 11m amps or are they specifically designed for 49MHz?

Thanks!
Click to expand...
Depending on how many of them you have .... you might just be sitting on a little gold mine there.
 
It would all depend on how readily available these finals are. If they are still out there in large numbers then next it would take an amp builder willing to try and come up with a design that works. Off hand I would say if it was possible and profitable someone would have already done it.
 
The SD1446 transistor so popular for CB amplifiers from the 90s to mid-2000s was specified for 50 MHz. Works okay on half that frequency, but requires only half the drive power it needs at 50 MHz.

Good chance the transistors in those radios will exhibit the same personality trait.

73
 
9C1Driver said:
It would all depend on how readily available these finals are. If they are still out there in large numbers then next it would take an amp builder willing to try and come up with a design that works. Off hand I would say if it was possible and profitable someone would have already done it.
Click to expand...
Maybe, maybe not. VHF transistors are more expensive to begin with and we know how cheap some people can be.
 
Hopefully this winter I will get that shed cleaned out and see whats in there. I know I have at least 7 of the medium-sized mobiles but only two of the big ones that mount behind the seats with remote faces. Those are the two with the huge heat syncs. I have no idea of the smaller mobiles have the final MRF's or if they are modules.
 
Motorola 2-way radios tend to have Motorola house numbers on them. As a rule, they use mundane transistors with their 'house' number substituted. Trouble is, only a short abbreviated portion of the actual part number from the service manual is printed on the part. That's all that will fit. Deducing the missing part of that number kinda requires that service manual. More than one sales company will have their own cross reference from that number back to a number you can find in the transistor's data sheet catalog. Just where they come by that info is kinda murky.

And if you spot a number you recognize, starting with "MRF" or "SD", so much the better.

73
 
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brandon7861 said:
I have a bunch of old motorola radios (I assume some are 100w at least due to the huge heat sync and big MRF's). I don't use 6m so I am thinking of either parting them out or building an amp or two out of them. Without digging in the shed to look at the part numbers, does anyone know if those 49MHz finals are good for use in 11m amps or are they specifically designed for 49MHz?

Th
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