A Modular Transverter for 3cm - page 4

Those with sharp eyes might have noticed the green cable-tie in the previous photograph. When doing final tests on the system I encountered a couple of issues relating to the PA. Unlike all of the other modules, this is constructed on a very thin flexible substrate. This is by design and for reasons that I am not qualified to go into. A down-side of this is the flexibility of the material. I found that weight or lateral force on the SMA launchers caused them to move. This actually caused the output track to fracture requiring repair. This movement also appears to affect the input matching. Hence the green cable-tie … it adds rigidity. It should be noted that Alan’s modules all carry very early serial numbers. I have discussed my findings with Chris who informs me that he is now aware of a tolerance issue which resulted in the launchers’ tendency to move.

This is also the reason for the pillar securing the relay to the chassis … It adds that bit of extra rigidity and ensures that the output launcher on the PA does not move and flex the thin PCB. If there is a flaw in the mechanical layout of this transverter it is in mounting the PA in this way. Anyone attempting this transverter should take every effort to ensure that the SMA connections to the PA do not put extra strain on the launchers and cause the board to flex.

Below is an audio recording of GM3WOJ’s personal beacon as received on this transverter from a location on the side of the Braid Hills in Edinburgh using the setup on the right.