[Elecraft] K2/100 Extreme high Power Out - What did I do?

[Bob Mallory]

Thanks Don,
Your right on target, I was thinking that it was a standard RS232 
connection, that probably what got me in trouble.
I have the correctly built I/O cable for use with the K2/100 and a 
KAT100 to the serial port on my PC.  Has been working with HRD for quite 
some time.
I recently acquired a ICOM R75 Receiver and without thinking much about 
it, unplugged the K2/100 and KAT100 connectors and placed the KAT100 
connector on to the R75.  This was my 'thoughtless' attempt to use the 
ICOM R75 with HRD.  It wouldn't communicate.  With no real concern to 
attempt to troubleshoot, I decided to re-connect the K2/100 to the I/O 
cable but inadvertently left the R75 connected to what should have been  
the KAT 100 connector.  Powered on the K2 and had instant smoke.  Smoke 
wasn't visible but you can't mistake that distinct smell. (took about 10 
sec to notice)

I powered off, disconnected the R75 and tested the K2 connection to 
HRD.  Everything seemed to work.

I felt it necessary to pop open the K2 and take a look around the AUX 
I/O port circuitry and everything 'appeared' ok.  Not until I later 
attempted to Transmit, did I notice a problem.  Yes, I could have 
injected a problem when I removed the cover of the K2.

I built the K2/100 and the KAT100 about one year ago and the build went 
flawlessly.  Now I think my momentary lapse of common sense has caused 
some problems.

The Tuner will tune the separate bands to give an appropriate SWR but my 
Watt meter (LP-100A) is showing 147 watts when using the 'Tune' button.  
It normally only shows approx 17 watts.

I plugged in the Elecraft Dummy load (20 watt) and the Elecraft W1 Power 
meter and a QRP 'Tune' shows NO Power out.  Turn the Power Dial up to 
activate the KPA100 and the Wattage immediately jumps to 140+ on the W1 
watt meter.  Obviously the 20Watt Dummy Load is not happy with that :)
Bob KD8HXT

Don Wilhelm wrote:
> Bob,
>
> The first thing I want to mention is that the K2 does *NOT* have an 
> RS-232 port connector!  You will do yourself a big favor by thinking 
> of that 9 pin connector by the name that is on the K2 - AUX I/O.
> The connector does contain 3 RS-232 defined signals, but the rest are 
> internal K2 signal lines that can be damaged by connecting a standard 
> computer serial cable.  Use only the special cable (instructions in 
> the KIO2 and KPA100 manuals) between the K2 and the PC.
>
> In order for us to better understand what may have been damaged, 
> please tell us what type cable(s) you had connected at which points 
> when it failed - please include the Icom, the K2 and the PC, how the 
> cables were connected and what type cables were connected at all points.
>
> It may be that the interconnections had nothing to do with the K2 
> failure, and you had a static discharge that damaged the wattmeter in 
> the KPA100 (or KAT100).  Please tell us whether this is a K2/100 and 
> with or without the KAT100.
>
> 73,
> Don W3FPR.
>
> Bob Mallory wrote:
>> Experimenting the other day, I had used my RS232 cable to connect a 
>> Icom Radio to my PC.  When I reconnected my K2, I forgot to 
>> disconnect the Icom.  I let smoke out of the K2!.
>>
>> Everything seemed to work, PC control, receive, etc.  Except on 
>> Transmit, (with Tune button) with a dummy load I have either '0' out 
>> on low power or 148 watts on high power, nothing in between.  No 
>> modulation out.
>>
>> Before I dig in, any suggestions?  I tried to search for smoked 
>> components, but nothing obvious.
>> Why would the RS232 port have an impact on the Transmit circuitry.
>> Thanks for any suggestions as a starting point.
>> Bob - KD8HXT
>>  
>
>