Although the K2 is a great transceiver the addition of a second receiver adds a lot of fun and effectiveness when using the K2 for both DXing and contesting. I have two K2s which I like to use as a linked pair. I am not at the moment interested in SO2R operation - I just use the second K2 for receiving, but I did want to interface them to each other and to the logging programmes I use. After I had gained some experience with the first version of the controller I decided that a number of changes needed to be made. This version uses much better software and has a couple of new features. Let's call the two K2s K2T ( the transmit K2 or your 'main' K2) and K2R (the 'second receiver' K2)
Basically the new controller :
- allows frequency and mode info to be ccopied from either K2 to the other.
- has a 'SWOP' feature which swops frequuency and mode between K2s but on releasing the button or footswitch it swops back.
At the same time it also swops the headphone sense (see later)
Being able to copy frequencies between the two K2s makes a very effective combination to break split frequency pile ups.
And with these new feature you can use the combination for contesting too. The arrangement would probably work with any brand receiver if the appropriate software changes were made. The method of operation is as follows.
Both K2s are controlled via their KIO2s. On wishing to copy frequency info. Each K2 is first interrogated by the controller which then sends the required commonds to the second K2. The Controller manages at the sametime any switching of the various RS232 lines between the radios. Logging programmes normally poll your radio for frequency/mode information via an RS232 interface (KIO2). using the same commands. The Controller interleaves these commands and avoids confusion. It is the status information of K2T which is sent to the logging programme. The controller however scans buttons and a footswitch to check if any has been pressed. The two K2s seem to be able to complete any changes within a few 10s of mS and less than the cycle of the poll from the logging programme. As written this programme will now recognise most commands from a logging programme -including direct frequency jumps from Writelog/LOGGER etc.
The specification of the two K2s is:-
|Transmit and receive K2 - K2T||Second receiver K2 - K2R|
My logging programme is LOGGER and for contests I use WRITELOG. They are both set to the Kenwood radio specification.
The controller allows one to copy frequency and mode information between the two K2s. At the same time it interfaces with my PC logging programme.
The Controller is quite complex due to the need to control timing and to ensure data integrity (these were problems with the first version)
K2T, K2R and the logging PC are interfaced togethervia RS232 to CMOS converters. These are to buffer the controller from the RS 232 lines. It would be possible to dispense with these but its better to have the right voltage levels and the buffer between the circuitry.
The system uses the RS232 interfaces on the K2 and the commands described in the Elecraft KIO2 Programmer's Reference. The audio section to the left uses a DIL relay to switch the audio between the left and right ears - the relay is controlled and sequenced with the 'SWOP' commands.
A new electronic switch is installed in K2T which allows internal connection of K2R to the antennas in use. Connecting the K2R in parallel across K2T does not appear to affect the receiver performance. The electronic switch circuit is based on the K2 antenna switch and is switched with 8R. The switch is mounted on the RF Board transverter header (J13 RF Board) as a plug in module, see picture. The components used are the smallest I could find. A new BNC socket was fitted to the lower back panel of K2T close to the RX Antenna socket.
The RX Ant socket is connected to the new RX Out socket on K2T in 4. K2R is set up as follows:-
RX Ant is selected for ALL bands
Power Control zero
STL is 000
Normal antenna terminal connected to dummy load ( this is for protection only)
Select TEST (this needs to be selected each time since it is not a remembered setting for K2, but see software below)
As K2R does not have a SSB module the filters are set up is as the manual, with three wide settings for SSB as well as settings for CW which are the same as those for K2T.
Interconnecting two K2s so closely shows up some spurs which are not otherwise audible. Mostly these are at low level, but there are on some bands digital artifacts from the other K2. Also there is a very low level signal caused by low level leakage . This signal appears on or close to the frequency when both K2s are set to the same frequency. Steps are underway to design a better isolation circuit between the two radios.
- align K2T so that it is exactly as youu like it.
- set the 4MHz osc in K2R to be the samee as K2T (it will in any case be very close)
- run CAL PLL on K2R.
- copy down all the filter settings fromm K2T
- set K2R filter settings to the same.
If anyone can get things closer then please let me know.