Try this old trick.
I used it with great success when switching high current dc.
get a multi pole relay, then wire all the contacts in series, that way
when the relay opens up, you have several air gaps the dc must breach.
Try a two pole relay first, remember you do NOT parallel the contacts,
you wire them in series. In on one, out of the other, in on the next
and the out to the load.
Mike, WB8VGE
SunLight Energy Systems
The Heathkit Shop
http://www.theheathkitshop.com/
J e e p
o|||||||o
Note: No trees were killed in the sending of this message, but a large
number of electrons were terribly inconvenienced
On Dec 10, 2009, at 1:17 PM, Steve Berg wrote:
I may have asked this her before, but I thought I would post it
anyway. One of the oldest radios in my modest collection is a Gonset
G-76 transceiver. I bought it used from AES in 1965, but was too poor
as a starving high school student to afford the companion power
supply, so I cobbled one together in breadboard fashion, and used it
for years. But, the voltages were never quite right. Now, Gonset
power supplies are virtually unobtainable, but I noted that the Drake
power supplies had the right voltages for my relic and bought one. I
plan to get the Heathkit Shoppe update for it. But, here is my
dilemma. The G-76 requires that the power supply disconnect the 650
volt DC line from the rig during receive, and ground the line going to
the radio. I used to use a surplus ceramic 12 volt relay to do this,
but that one has vanished somewhere in the past 40+ years. I have
tried to use normal power relays, but their contacts are seemingly set
up for breaking lower voltage DC, or are self quenching when breaking
AC. I have had some rather spectacular arcs in a few relays when
trying to use them for this application. Where might I find a 12 volt
AC coil power relay that will reliably open a 650 volt DC circuit, and
ground the far side that is going to the radio? Normally this would
be a simple SPDT relay.
Also, I want to make any modifications as reversible as possible as I
do not want to modify it so much that it would not be usable with a
Drake rig in the future.
Help?
Steve WA9JML
_______________________________________________
Drakelist mailing list
Drakelist@zerobeat.net
http://mailman.zerobeat.net/mailman/listinfo/drakelist
_______________________________________________
Drakelist mailing list
Drakelist@zerobeat.net
http://mailman.zerobeat.net/mailman/listinfo/drakelist
