[Elecraft] Ouch

[Don Wilhelm]

Mike,

I am sorry to hear that you had such an incident.    Unfortunately, you 
may not be alone in your woes.  Such events are not uncommon among Field 
Day reports.

The basic K3 is protected by a series reverse protection diode, and 
should be OK.  Unfortunately, there is not such protection for the KPA3 
because the added 0.3 volts drop of a diode rated at 20 amps is not 
practical.

I would expect that the damage is restricted to the KPA3, and may 
require replacement or major repair.  Contact customer support at 
K3support at elecraft.com to review your repair options.

There may also be damage to your SG-231 autotuner as well, but Elecraft 
customer support cannot help with that.  Try the K3 working into a 50 
ohm dummy load and see what the results might be. Elecraft can help with 
analysis of the damage for that part of your problem.

'Closing the barn door after the horse is gone' is not really helpful, 
but I would advocate the use of Anderson Power Pole connectors with 
fuses right at the power supply end of the power cord as prevention for 
the future.  Properly constructed APP connectors are 'genderless' and 
can help prevent such incidents.  I just returned from Field Day 
operation with 2 of my Elecraft rigs with no problems, but I use APP 
connectors on each piece of the 12 volt supply for all my gear.

One gentleman at the Field Day site used one of my power supplies to 
power his Omni, but he did not use APP connectors in his system.  I gave 
him the power supply (with APP connectors) and allowed him to change the 
connections to the power supply output at his own peril - fortuntely, 
there were no problems.
In my system, the power supply is fused within inches of the power 
supply end (both the positive and negative leads with fuses rated for 
the wire size used in the cable - see AWG tables) and all the rest plug 
into a Rigrunner or other distribution box with fuses rated for each 
branch.  The fuses should be sized for the smaller of the wire size in 
the power cable or for protection for the gear on the 'business end' of 
the power cable.  I fuse #12 power cable to a 100 watt class transceiver 
at 25 amps.

73,
Don W3FPR

On 6/29/2014 11:23 PM, Mike Lewis wrote:
> So about 20 minutes prior to starting another successful Field Day with my
> trusty K3 I powered it up for the first time after connecting everything had
> just started some tests when my buddy starting yelling that I was letting
> some of the magic smoke out of the radio. Sure enough, there was smoke
> coming out of the back of the radio. I dived over and pulled the power. To
> make a long story short, I was running an S9 31' vertical antenna base tuned
> with an SG-231 autotuner, with the auto tuner powered over the coax using DC
> blocks. The exact same config as I ran with last year with wonderful
> results. Unfortunately this year in my excitement I carelessly installed the
> DC block at the radio end BACKWARDS, sending the 13.8v from my 30 switched
> supply right into the antenna jack. After the incident I powered back up
> with my finger on the off switch to try to assess the level of damage. The
> radio puts out some power, but the SWR is infinite even into a dummy load. I
> am not sure of the status of the receiver input chain as I didn't want to
> put it back onto a real antenna.
>
>