[Amps] Alpha Switching Diodes
jim.thom at telus.net
Wed Mar 1 09:50:09 EST 2017
Date: Wed, 1 Mar 2017 00:53:46 -0800
From: Jim Brown <jim at audiosystemsgroup.com>
To: Amps Amps <amps at contesting.com>
Subject: [Amps] Alpha Switching Diodes
I've heard that Alpha came up with a fix for problems with their
switching diodes on the 87A and 89 amps. I just bought one of each. Can
anyone shed light on this?
73, Jim K9YC
## yeah, its called vac relays, used on newer alpha amps. Having said that,
the pin diode tr switching diodes in the 87-A never seem to have issues, where
as the same pin diodes in the manual tune 89 do..dunno why that is.
## Gigavac GH-1, Jennings RJ1A, or a kilovac HC-1 are all the same, and all
will easily switch in less than 1.8 msecs. The gigavac GH-1 is the best of the bunch,
and will easily hi pot test to over 7.5 kv.
## a buddy used 3 x gigavac GH1s on his hb 6m GS35B amp. 1 for input, 1 for output,
3rd one for the bias. Then its easy to sequence them for qsk operation. With a vac relay
on both the input and the output, then you can also stuff 2 kw through it on bypass. That
comes in handy when you wire 2 or more amps in series, nose to tail. I do that with my 4 x drake
L4B amps. Then the key line from xcvr to a simple rotary switch. Output of rotary switch is
fed to each of the 4 x amps key line inputs. Simple mech interlock. Then only 1 amp can be
keyed at any one time.
## a buddy has an alpha 87-A. It has the high and low B+ position. On the low B+ position,
running half power, the plate xfmr buzzs. Never did figure that one out, has anybody else
experienced this ? The new alpha amps dont have a hi + low B+ position, too bad. That
comes in handy some times. If you want lower power, its more eff when using lower B+.
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