Matched transistor set question?

[long night]

Hi to all. I have a amplifier that uses mosfet transistors. Two are bad. Do you need to purchase a complete matched set of mosfets for replacement like you you would with regular pill amp?

Thanks in advance for the information.
Chuck Saylor

 

[nomadradio]

If what you mean by "MOSFET" is the generic IRF-520 or FQP13N10, those are made by numerous vendors. Using parts from the same factory is the least amount of "matching" I recommend. Ordering by the part number alone won't guarantee new parts were made by the same vendor as the old ones. Too many different outfits making them.

We use a cheap Ebay tester to measure the new MOSFET's turn-on voltage or "Vth". The reading on the tester is what we use to 'match' sets of two, four or more. Just how many you need to order to get a set that match is anybody's guess.

In general, the only way you'll get matched parts into the equipment is to replace them all. Finding new parts that will actually match the used ones is either a lot of trouble, or just not practical.

73

 

[long night]

If what you mean by "MOSFET" is the generic IRF-520 or FQP13N10, those are made by numerous vendors. Using parts from the same factory is the least amount of "matching" I recommend. Ordering by the part number alone won't guarantee new parts were made by the same vendor as the old ones. Too many different outfits making them.

We use a cheap Ebay tester to measure the new MOSFET's turn-on voltage or "Vth". The reading on the tester is what we use to 'match' sets of two, four or more. Just how many you need to order to get a set that match is anybody's guess.

In general, the only way you'll get matched parts into the equipment is to replace them all. Finding new parts that will actually match the used ones is either a lot of trouble, or just not practical.

73

Thank you so much for this information sir!