[Elecraft] [K2] Solutions for K2 Transverter Quirks

[Don Wilhelm]

Steve,

The answer to your question involves a discussion about how the K2 
handles control of the power output level - in all cases, it tries to 
measure the actual power output and the microprocessor controls the 
drive level early in the transmit chain to achieve the power output 
requested by the power knob.

Just as information about what is happening with that "RF Sensitivity" 
problem is that *if* some of the VHF/UHF energy appears on the K60XV TX 
output.  That condition causes the RF detector on the K60XV to produce 
an output on the VRFDET line in the K2 (the detector is not frequency 
selective - it is just a diode, similar to an RF probe) - the result of 
all that is the K2 microprocessor ends up receiving a signal telling it 
that there is too much power at the TX output, and the microprocessor 
dutifully reduces the power.

The simple low pass filter is just as effective at curing that condition 
as a unity gain buffer stage would be.

The ideal solution would be to modify the transverter so that none of 
its output frequency energy appears on the input cable, but that is not 
realistic in some situations - it all depends on the transverter.

73,
Don W3FPR

On 11/8/2011 8:15 AM, Steve Kavanagh wrote:
> My apologies regarding the link...as W1RT correctly figured out there should be an L at the end of it:
>
> www.qsl.net/ve3sma/downloads.html
>
> I had seen Don's circuit and decided to go a different route...not having to dig into the K2 was a plus for me (and I had a good supply of the Omron G5Y PC-board-mount RF relays).
>
> I had wondered how W1RT dealt with the RF sensitivity of the transverter out line....now I know !  I have been thinking lately a better solution than the filter might be a high isolation buffer amp with 0dB gain (or an attenuator and then a buffer with gain) built into the K2, but I haven't started looking to see where there might be room.
>
> 73,
> Steve VE3SMA
>