[K3] [Elecraft] K3 power tripping out

[Ron D'Eau Claire]

While a bad connection in the power certainly can cause this, it's worth
checking your power supply "crowbar" point. As you know, most power supplies
have over-current protection (crowbar circuit) that shuts them down if the
current exceeds some preset level, even instantaneously. 

Some supplies, like my Astron, shut themselves down completely, requiring me
to cycle the power switch on the Astron to restore power and alerting me to
just what happened. But others don't. They just shut down for as long as the
over-current condition occurs, so all you need do I push the K3 POWER button
to restore operation.

You are quite right that the current varies according to the SWR. It also
varies by band because the overall efficiency of the K3 varies slightly over
the bands. I have an Astron 20 which is fine with the K3 but close to the
current limit on some bands making it more sensitive to absolutely low SWR
on some bands since it draws nearly 20 amps at 1:1 at 100 watts output.

Another common issue is an improperly mating Anderson PowerPole connector.
It should require a solid "tug" to disconnect the power cable from the rig,
indicating that the flat leaf spring contacts are mating fully. 

One cause of bad mating is that the contacts are not fully inserted into the
connector housings. If they are, you cannot remove the contacts by pulling
on the wires. The contacts snap over an edge near the open end of the
connector when they are fully inserted.

Of course that's true for the connectors on the back of the K3 too, but
those come pre-assembled and should be right. 

Ron AC7AC

-----Original Message-----
From: elecraft-bounces at mailman.qth.net
[mailto:elecraft-bounces at mailman.qth.net] On Behalf Of Jon K Hellan
Sent: Thursday, December 04, 2008 6:10 AM
To: G4AFU Paul
Cc: elecraft at mailman.qth.net
Subject: Re: [K3] [Elecraft] K3 power tripping out

G4AFU Paul wrote:
> For some unknown reason my K3 (897) tripped out 3 times last night when on
> 160m cw. 
> I was running 90w out with a 1 to 1 swr - auto ATU installed. 
> Each time I brought it back to life by hitting the POWER button.
> 
> It is a little disconcerting when in mid QSO!
> 
> Has anyone else had this happen to them?

This happens to me when SWR is a bit off, and also happened with my previous
rig. I haven't measured,
but I suspect that it's pulling more current, making the power supply
voltage drop. I can usually
avoid the condition by turning power back a little - say to 70 or 80 W. The
power supply is rated for
25 A.

73
Jon LA4RT
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