Carl,
> Suffice it to say that the real world of tube type ham amps uses the 1N5408
> almost universally no matter what the configuration.
Do the Alpha 8410, 9500, 8406, and the 89 belong into the real world of tube
type ham amps? I would say, they do. And they don't use the 1N5408 but instead
use a potted bridge rectifier, rated at 5kV peak inverse voltage and 2A total
forward current. I don't know with certainty what's inside it, but 4 strings of
5 each 1N4007 diodes would have exactly those ratings. Instead a bridge made
from 1N5408 diodes would have a rating of 6A total.
This is it:
http://www.rfconcepts.com/REPLACEMENT-PARTS-LISTED-BY-ALPHA-PRODUCT/Blowers-and-Fans_2/HV-Bridge-Rectifier
Maybe it doesn't use the 1N4007, but then certainly it uses some other diode
very similar to it, and not at all like the 1N5408.
They rate it for 50A surge of 8.3ms duration, which might mean the diodes inside
are slightly beefier than the 1N4007, or maybe the difference is just due to to
larger thermal mass thanks to the potting. If different, this could be 1N5622
diodes, which have that 50A surge rating. But that diode has a slightly higher
voltage drop, which isn't consistent with the bridge's rating for voltage drop -
while the 1N4007's is consistent with it!
I suspect this bridge is simply made from 1N4007 diodes, nicely potted, and sold
for $150...
Take $2 worth of diodes, a little plastic case, 4 blade terminals, 20 drops of
solder, and a few grams of a good epoxy potting resin, put it all together, and
sell it for $150 to hams. Hmm, I should get into that business! ;-)
On the other hand I do admit that several other amps I checked, indeed use
bridges made from 1N5408 diodes. But the Alphas are too important an exception,
to ignore them!
Manfred
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