[Elecraft] Can Bluetooth be used to replace link between K2 and remote KPA100+KAT100

[Don Wilhelm]

Harry,

First, the signals required to operate the KPA100/KAT100 remotely are 
*not* RS-232 signals.They are 'hard-wired' signals to and from the base 
K2.  Note that the connector is labeled AUX I/O - the fact that there is 
a DE-9 connector on any piece of equipment does not denote RS-232 unless 
explicitly stated, and the K2 is no different.

Secondly, I believe you will encounter timing problems on the AUXBUS 
signal (the one wire K2 signalling line between the firmware ICs in the 
Elecraft gear.  It will likely work up to 2 meters, but 10 meters is 
stretching it a lot.  You would have to do extensive testing to 
determine that 10 meters of cable will work with no problems.  The 
AUXBUS carries data that requires a response in a certain period of time 
and that timing is critical.

The other internal signals used to connect the KPA100/KAT100 are not 
likely to cause problems unless the cable resistance is a problem. Those 
signals are:
+12CTRL - this is a 12 volt line that is active whenever the K2 is 
powered on.
8R ---- this signal controls the transmit/receive switching, Whether 
propagation delay would prove troublesome over a great cable distance 
remains to be tested.
VRFDET -- This carries the measured power output from the KPA100 
wattmeter back to the base K2 so power output control can be 
maintained.  Again the resistance of the wire may be a factor in correct 
operation.

Better to bring your KPA100/KAT100 inside in the warmth of the shack and 
just run the output coax(s) to the shed and antenna field.

73,
Don W3FPR


On 1/26/2013 12:16 PM, harry weston wrote:
> Hello. I am assembling KPA100 and KAT100 into an EC2 case, and intend to use the K2 indoors, where I can keep snug and warm, with the amplifier and tuner in a shed outside, less than ten metres away, and close to the antenna. Can I use a Bluetooth RS232 serial replacement pair for this communication link? I am concerned because we are warned against using a standard RS232 cable to link them, and the Bluetooth modules are rather expensive to buy for an experiment, unless I am pretty sure it will work. Thanks, Harry Weston M0SOP
>