[Elecraft] Using K3 for 2m EME

[Don Wilhelm]

Lance,

My guess is that you will need to change to the external XV144 
transverter which does have the capability of using  separate TX and RX 
antennas (selectable at build time).  The internal transverter does not 
have that capability.

Yes, it does sound like an expensive oversight.

73,
Don W3FPR

On 4/8/2013 7:37 PM, Lance Collister, W7GJ wrote:
> I wonder if anybody has any ideas about this.  Prior to my trip to 
> TX5K, I used my K3 for receive on 2m EME by setting up the transverter 
> port for a 28 to 144 MHz transverter, and I just plugged my 28 MHz 
> converter into that nicely isolated receive port.   The receiver 
> worked great, but I was eventually interested in getting the internal 
> 2m transmitter module so I could use the more stable K3 on XMIT too.   
> I was using my old IC746 as a separate transmitter on 2m EME, and - as 
> most of you know - it drifts quite noticeably every sequence.  And 
> besides, I thought for traveling it would be convenient to have both 
> 2m and 6m capability in one lightweight box.
>
> So, now I have the 2m module installed in my K3 ;-)  The problem is 
> that I can no longer use the transverter port....it is hard wired to 
> the 2m module.   And apparently, the only 2m connector is the new one 
> (a BNC called antenna jack #3) that is used for box receive and 
> transmit.   So there seems to be no way to use the K3 with a separate 
> protected receive line anymore!
>
> For 6m EME, there is no problem - I just bring my 6m preamp line into 
> the separate RX ANT jack, and the 6m transmit power goes out through 
> the UHF antenna jack #2.   For 2m EME, though, I can't figure out how 
> to bring in a separate receive line (either on 2m from my tower 
> mounted preamp or after my receive converter at 28 MHz) and still be 
> able to transmit on 2m.  The K3 does not support cross band operation, 
> so I cannot use the RX ANT jack to safely receive my converter output 
> on 28 MHz and still transmit using the internal 10w 2m module.
>
> Has anybody figured out a way to modify the circuitry or software to 
> provide a separate receive line for 2m operation?  It seems like I 
> just made a very expensive mistake, and should have just bought an 
> external transverter so I could retain use of the separate transverter 
> receive jack on the rear of the K3.   If not, I guess I will just have 
> to go back to using the IC746 for my transmitter on 2m, and defining a 
> second transverter setting for the K3 that will allow me to bring in 
> my 28 MHz converter output into that receive only jack.  This latter 
> option DOES seem to work, but of course, the internal transmit 
> capability of the K3 on 2m is thrown out the window.
>
> Of course, there is always the solution of adding more sequenced 
> external coaxial relays to switch the K3's solitary new BNC antenna 
> jack #3, between my driver amp input and my 2m preamp output. However, 
> the whole point of this expensive exercise was to try to take 
> advantage of the great separate receiver antenna capabilities offered 
> by the K3 on all other bands, apparently EXCEPT if you add the 
> built-in 2m option :-(
>
> Any suggestions would be greatly appreciated.    Elecraft Tech Support 
> suggested that I ask users for ideas, since they also are baffled on 
> how to make this work, and I guess are surprised at my application.   
> MNI TNX and VY 73, Lance
>