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Vintage Amateur and Military Radio Amateur/military receivers and transmitters, morse, and any other related vintage comms equipment.

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Old 29th Aug 2020, 11:51 am   #21
crackle
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Default Re: Superstar 360FM

Oops I have just noticed I typed the wrong transistor number in my first post. 2SA2012 should have been 2SA1012.
I have asked for it to be corrected.
Thanks
Mike
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Old 29th Aug 2020, 10:00 pm   #22
SiriusHardware
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Default Re: Superstar 360FM

Significantly more gain probably would not affect matters in SSB mode since the transistor is meant to be turned on flat-out in that mode.

In AM mode it could conceivably make a difference to the AM modulation depth, so again, ideally you just want something as close to the spec of the original part as possible. It can be the same or higher voltage rated, the same or higher current rated, but try to go for something with the same hfe.
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Old 29th Aug 2020, 10:06 pm   #23
crackle
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Default Re: Superstar 360FM

Thanks, not having a lot of luck, there is not much to choose from, everything now seems to be surface mounted, or cheap Chinese copies with stock photos.

Mike
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Old 8th Sep 2020, 9:04 pm   #24
crackle
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Default Re: Superstar 360FM

I thought I would just let you know that I got 2 types of transistor to try as replacements for the 2SA1012 AM modulator/voltage regulator.
I first bought a 2SB920 which was an original green colour one on ebay which came from Holland, but then I found this one on Farnell MJE15031G.
As I was buying some more IRF520 mosfets from there I decided to buy the MJE15031G as well.

I have fitted the MJE15031G and the radio is working fine in all modes. So I am suggesting to the owner we keep to this one as its a more capable transistor.

Here is a comparison of the specs of the original and the 2 replacements I bought.
Click image for larger version

Name:	2sa1012 comparison.png
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ID:	215248

Mike

Last edited by crackle; 8th Sep 2020 at 9:11 pm.
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