UM4006D are now $60.00 each at Mouser Elec.Sent via the Samsung Galaxy S9+, an
AT&T 5G Evolution capable smartphone
-------- Original message --------From: dbritchie@gmail.com Date: 3/16/21 7:20
AM (GMT-06:00)mTo: amps@contesting.com Subject: Re: [Amps] Looking for Alpha
87A expertise (David W6DR) I wouldn't say I am an expert on the Alpha 87A
although I did own one anddeal with issues inside it for several years. It was
a good amp and itsbest feature was the quiet and reliable PIN diodes making
real QSK not onlypossible, but normal. I never managed to kill mine. I did
trade it in toAlpha for a 9500. As far as PIN diodes are concerned, you can
download theSPEC sheet from Micro-Semi (UM4006D/SM) and for 1N4007s you can
download theSpec sheet from any company that makes them. UM4006D/SM PIN diodes
runabout $16 per; 1N4007 diodes run about $0.03 per. So on price it ought tobe
fairly obvious that there is a difference here. Looking at the specsheet, the
speed of switching of the UM4006D is incredibly high (like 5uSec) - the 1N4007
doesn't appear to be specified except to confirm that itworks well at 60 Hz.
If 60Hz works for you - go for it. But this is a T/Rrelay we are talking about
and you don't want the power going to the wrongplace for very long. And 1/60
second is VERY long for 1500 Watts to begoing to the wrong place. (1/60 second
= 16700 uSec).From what I have read, the failures tended to occur in earlier
units due toa less than optimal installation protocol during manufacturing.
(10/05/2017Amps Post from WC1M).Microchip Technology Inc. appears to have units
available for sale right now- possibly others, and there appear to be
alternates available.I am enough of an expert to know that I would rather
replace a dead partwith a same thing replacement than attempt to reengineer a
critical circuitthat will kill my expensive transceiver in a few microseconds
if I get itwrong. Especially if the part costs less than $20. Good luck.Dave
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