Conway Yee
Thu, 27 Jun 1996 17:18:45 -0400

Jim (VE3DDY) writes:
>A good "noise source" to test the blanker is to connect up a 12 v DC
>relay with one of its N.C. contacts in series with the supply. The
>resultant buzzer and spark at the contacts makes a wonderful noise
>source for testing the noise blanker.  This circuit simulates auto
>ignition noise.

Is this true?  I have been thinking about putting a 12v DC relay in my
Corsair II so that I can use the front panel on-off switch.  I never
liked the idea of controlling power to the rig by turning the power
supply on/off like TenTec seems to like to do.  In addition TenTec
seems to like to deal with high SWR by good current limiting on the
part of the power supply.  I don't like that too much either.

Looking at how DC power supplies are designed, I suppose it is easier
to do current limiting at the power supply end but from a
philosophical point of view, I believe that every piece of equipment
should be as self-sufficient and untrusting as possible.  Why should
the HF rig trust that another unit, a power supply, will properly
limit the current?  Why should a rig trust a power supply to turn off
its 12V output when the rig's on-off switch is used?

Wrt using a relay to use the front panel on-off switch with non-TenTec
power supplies, this is a mod that TenTec itself recommends in the
users manual (Corsair II).  They recommend a Potter-Brumfield relay as
one of two possible choices.  I never liked the idea of my having to
install the relay when I felt that it should have been a factory
standard default.  Perhaps TenTec may have a good reason other than
convincing end users to buy their power supplies.  How bad will the
noise be?