4m transverter boxed and finished (for now)

G3XBM 4m transverter - finished (for now) with 2-3W pep

Another good day today saw the 4m transverter completed and even boxed. I also did the FT817 DC switching mod  to put 5V DC on the antenna pins when on TX. It was easy to do, with care, and made the transverter switching so much easier. Don't understand why it was not there as standard for the sake of 1 capacitor and 1 resistor. The limitations with the current design are:

• IF breakthrough rejection at 28MHz is not brilliant, as one would expect from a single tuned circuit on the NE602 input. I can change the input to a top coupled pair to help, but will see how it behaves on-air first.
  
• LPF on the PA is just a single 3 component Butterworth. At some point I should add another section, but as the drivers/PA are linear all the way through, the 2nd/3rd harmonics should be reasonable already.



GB3BAA 4m as received

• The TX strip has DC power on it even on RX. I need to arrange to switch this off later, but I am not worried that there is another 50mA or so when on RX at the moment.

This evening I have rigged up a horizontal dipole for 70MHz in the loft and am ready to find some locals to work. So far just the 70.016MHz GB3BAA beacon 89km away visible well with Spectran (20dB S/N).