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
[email protected] 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.
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