[R-390] MOV's and snubbers

[David Wise]

The formula in the Illinois Capacitor app note computes the same values as the HA-1 chart.

For the 120V 1A-2A load of the R-390A, that's 0.1uF and 8 ohms to 0.4uF and 4 ohms.  Next time
I have mine apart I'll put one in.  I'll use 0.1uF and 10 ohms, and add it to the Mod List.

Dave Wise

-----Original Message-----
From: r-390-bounces at mailman.qth.net [mailto:r-390-bounces at mailman.qth.net] On Behalf Of Roy Morgan
Sent: Saturday, January 25, 2014 9:06 PM
To: Phil Mills
Cc: R-390-List
Subject: Re: [R-390] MOV's and snubbers


On Jan 25, 2014, at 10:12 AM, Phil Mills <pmills7 at comcast.net> wrote:

> This begs the question....... The HA-1 keyer is most
> likely used for keying DC circuits.

Phil,

Yes, that certainly is the case.

>  Is that chart
> in the manual good for AC circuits?

Very good question, I suspect it was not meant for keying AC.

> Roy, thanks for pointing out that manual.  I used
> an HA-1 for several years and never paid any attention
> to that table or the need for a snubber.

You probably did not need to.  Most or all of the transmitters I've heard of being used with the HA-1 (HT-32, Ranger, Valiant, ... ) have keying voltage and currents that figure out by the chart to need NO snubber for the mercury relay.  So no worries.

Roy


Roy Morgan
RoyMorgan at alum.mit.edu
K1LKY Since 1958