Fisher 400 rectifier. Is this original?

daveyh

AK Subscriber
Subscriber
This looks like it is original but the guy who sold it says it has been changed. Most of these I have seen are metal cased. This is plastic. But it looks like the circuit has not been touched. This serial number starts with 699xx X.

Has anyone seen these before?
 

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Yep. It's original. The later series 400s in fact had silicon bridge rectifiers installed in place of the prior version's traditional selenium at the time. You really don't need to replace it unless you need the peace of mind. Don't know of any of the original silicon bridges that have ever failed though........

Dave
 
Yep. It's original. The later series 400s in fact had silicon bridge rectifiers installed in place of the prior version's traditional selenium at the time. You really don't need to replace it unless you need the peace of mind. Don't know of any of the original silicon bridges that have ever failed though........

Dave

Thanks Dave! Good to know I don't have to replace it.
 
Not that I'm aware of. I've seen them on the side of the chassis on a T-strip, and on the T-Strip mounted to the RF Box, why I haven't the foggiest! You'd think you'd want to keep a minimum amount of distance between the AC and RF sections, even shielded. But no heatsinks. I use the table style bridge and mount them right on the side of the chassis with some heatsink grease between the bridge and the chassis.
 
not to say they can't fail but generally when silicon diodes die, its because something else killed them. They rarely fail just because the day ended in Y.
 
One of mine also came with an attached heat sink. Don't know when they switched but both of mine have the one additional IF can but one had selenium, I'm assuming selenium because someone had already replaced the bridge, the other came with the silicone.
 
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