[Elecraft] K3 sudden power loss

[Philip Leonard WVØT]

Welcome to the club.  My K3 has done that twice.  It is currently in 
Aptos for repair of this problem...again.

Philip


Gary Hinson wrote:
> Hi all.
> 
> Yesterday afternoon my K3 #2887 was merrily transmitting 33% at 5W on
> 17m for WSPRnet as normal when by chance I noticed the external
> wattmeter was showing no power out on transmit - none at all, not a
> squeak.  The internal wattmeter is also showing no power out, aside
> from the first bar permanently lit in TX.  The receivers still seem to
> be working fine.
> 
> The rig was working OK up to then and has been since mid-April.  I
> wasn't fiddling with any of the settings at the point it packed up,
> but before anyone asks here are the ten checks I've done so far:
> 
> 1.  I tried sending CW and SSB - neither works.  Nor does TUNE, at any
> power setting.  Nor does any other band.
> 
> 2.  I tried using VOX on both semi and full break-in, and PTT - no joy
> there either.  The TX LED lights as expected but no watts escape.
> 
> 3.  I've plugged a 100W dummy load directly into the ANT2 socket,
> selected ANT2 and tried transmitting, just in case there's some cable
> or antenna problem.  Nope, that's not it.
> 
> 4.  The K3 is not in TEST mode (the TX light is on continous not
> flashing).  I cycled TEST mode on and back off to be real sure. 
> 
> 5.  I checked CONFIG: TX INH is off, and again cycled it through the
> other settings to be sure to be sure.  Nope, not that.
> 
> 6.  I tried running the TX gain configuration through K3 Utility: the
> front panel shows ERR TXG and the K3 Utility reports: Unexpected
> response "DS@@@@@>>@°À;" to "DS;" State 153   Calibration power
> settled at "  0.0 W .;"  There be gremlins.
> 
> 7.  According to the internal metering, the K3's voltage is reading a
> steady 13.5V and the current sits at about 1.28A on RX, increasing to
> about 1.62A when I hit the PTT.  No change from that level when I key
> the paddle or speak into the mike, whether whispering, shouting or
> swearing.  I even tried coaxing it to life, complementing it on the
> colour of its LCD ...
> 
> 8.  The power setting makes no difference: I've tried from 0 to 100W.
> I hear the PA relay engage around 12W as normal, and the internal
> power meter changes between high and low settings as expected.  It's
> just taunting me.
> 
> 9.  The 20A circuit breaker on the PA is in - not that I'd have
> thought it would prevent the QRP level working at least.
> 
> 10.  I've reloaded *all* the firmware: I was using the latest beta
> 3.25.  Reloaded that, no change.  Reloaded an older version 2.78,
> still no change.
> 
> What should I try next?  I guess I need to pop the lid, look for smoke
> emitters and poke around at the TX driver and PA stages plus the
> antenna change over relay and ATU area with a multimeter but haven’t
> figured out exactly where to poke yet, nor what I should expect to see
> on the meter when I do ...
> 
> I have other radios here and a scope.  I guess I could try to trace
> the TX signal with the K3 set to QRP, fishing around with a wire tail
> on another radio's antenna socket or the scope input ... Maybe ...
> What do you think?
> 
> 73
> Gary     :-(
> ZL2iFB
> 
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Elecraft at mailman.qth.net
> 
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html