[Elecraft] K3 Softrock Lite

[jo benoit]

Hello , 
While I was waiting for my K3 to arrive, I have been doing some experiments with the Softrock Lite . 
The softrock lite is an amazingly good rx for its 11 $. 
I was interested in a panoramic display, so I tried it out on the TS-850 . With a 35.362 Mhz Xtal and Rocky software that was not much of a problem. It worked just fine. 
For the K3 , I ordered a 32.812 Mhz Xtal . 
I read here that more isolation is needed to prevent the oscilator signal ( 8.204 Mhz in my case) to go back to the K3. 
Someone suggested the use of a HCPL-4562 . 
First I measured at the input of the Softrock, with the TS-850 and found a strong S9 carrier at 8.204 Mhz 
With the HCPL-4562 in front of the Softrock, I was able to hear the carrier on the input, but no indication on the S-meter. That should be enough isolation, I think. 
Then I added an extra stage . I copied the schematic from the K2 preamp with a 2N5109 to give the signal from the IF an extra 14 db or so and extra isolation. I still could hear the carrier , somewhat quieter, and see nothing on the S-meter. 
The whole thing is built into a metal box and shielded between the different stages, and an extra shield between the HCPL-4562 input and output. The connection between the K3 and the adapter is a short coax cable with two bnc plugs. 
When changing from xfil1 to xfil2 and xfil3 on the K3, I noticed a shift in the display, so I made three different entries in the rocky.ini file: in the [Band] section I added : 
FL1=8625 
FL2=9700 
FL3=9630 
I had to experiment with these values until the signal was at the zero mark on the scale . 
One important thing I overlooked was the fact that you need the KXV3 interface. It was only when I was building the K3 that I realised that... :) 
I have no special soundcard, I use the on-board soundcard of my pc. 
It works fine with Rocky, I haven't tried any other software ( yet ). 
73 de on5ao 


K2 #5237 
K3 #0324 

jo benoit


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