February 23, 2012

KN-Q7A Single Band SSB Transceiver Kit - Step 6: Mixer and VXO Local Oscillator

This is the 9th article in our series on building the KN-Q7A Single Band 40m SSB Transceiver Kit. In our prior article, we completed the IF Crystal Filter.
In this article we proceed with building Step 6: Mixer and VXO Local Oscillator.  VXO is the abreviation of Variable crystal oscillator.
We followed the instructions and installed the parts without incident.  We installed the 15.550 Mhz VXO crystal.  We also have a 15.418 VXO crystal which we intend to save and experiment with another day.
KN-Q7A build through Step 6: Mixer and VXO Local Oscillator
We touched pin 1 of the NE602A with an antenna cable tip as suggested by the instructions and detected band noises.

Lessons Learned
  • Our good old PanaVise 301 holds the circuit board securely making component placement and soldering very easy.
  • The instructions indicate touching pin 1 of the integrated circuit.  Beginners may find that locating pin 1 is a little confusing without a graphic.
  • We were unable to detect the VXO frequency change on our general coverage receiver on 7.280 ~ 7.300 Mhz.  We were picking up some weak stations and environmental noise on our general coverage receiver (TH-F6A) that perhaps interfered.  The instructions were not specific about where to tune or how to detect the VXO frequency change.  Hopefully our test result is a false positive indication of a problem.  We will proceed to the next step to confirm.
In the next installment the fun continues as we proceed with building Step 7: RX Front End and having a working receiver.