Minilink Development Version 2
Version 2
The issue with the de-emphasised audio on RX as discovered in version 1, was covered off by providing an opposite emphasis in the MiniLink (effectively “pre-emphasis” but applied at the end of the audio route). Initial tests showed a 3X improvement in RX data rate with the pre-emphasis in circuit. It was also decided that, while the isolation components (2 audio transformers and an opto-coupler ) weren’t likely to be required for hand held radios; having provision to optionally fit them would widen the potential use for the interface. A second PCB was designed to stack above the initial one, to accommodate the additional components. Solder dot links were added to select or bypass the optional isolation components, and also to enable or disable the pre-emphasis.
But wait – there’s more. Before a test sample was constructed, we moved on to V3 !