Replacement for 2SA473 (o)

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cb4ever104
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Replacement for 2SA473 (o)

Post by cb4ever104 » 26 Apr 2018, 08:43

Hi All .

Came across this post from RD250 .
RD250 wrote:
04 Aug 2011, 13:51
Yes, this is one part of the radio that shouldn't be tinkered with by someone new to faultfinding.
The reg is a LDO design with feedback and care must be taken to make sure the reg doesn't churn out 13.8V into the radio as this could cause damage.

Also if the DVM probes slip between the pins on the 2SA473 it can cause 13.8V at the reg output.

It's always best to replace with the original 2SA473 transistor because the reg circuit is designed for this (fast) PNP transistor. Any changes can alter the loop response of the regulator.
Eg fitting a slow PNP alternative might reduce its ability to regulate out spikes and ripple/noise.

Also PNP LDO regs are prone to instability if the phase/gain response of the regulation loop is altered with a different PNP transistor (or if other parts of the regulator circuit are swapped for non standard).
I must admit I do miss his technical insight .

Anyway . On the subject of the 2SA473 . What are we using these days as replacements ? I found some originals on Ebay .

https://www.ebay.co.uk/itm/272251998235

...which I'm going to buy , but I was just curious anyway .

Sammy
30TM060
Paul aka "Sammy". (108) PY60 Old Paisley DX Group (RIP Rab Markie)
Ex GM0 , now EA5 .
Handle "Fortune Hunter" back in "the day"
Radios ....? Anything that says "TAIWAN R.O.C" on the back.

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13EL121
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Re: Replacement for 2SA473 (o)

Post by 13EL121 » 28 Apr 2018, 22:01

Paul, a TIP42C works as a replacement. Did it in one of my Jackson. Works without problems.

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cb4ever104
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Re: Replacement for 2SA473 (o)

Post by cb4ever104 » 30 Apr 2018, 08:12

OK . Thanks Ralf . I've bought 10 originals , so hopefully they'll last for a while :)
30TM060
Paul aka "Sammy". (108) PY60 Old Paisley DX Group (RIP Rab Markie)
Ex GM0 , now EA5 .
Handle "Fortune Hunter" back in "the day"
Radios ....? Anything that says "TAIWAN R.O.C" on the back.

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