Translator

This page will give everyone detailled information about the construction and hardware of the translator system installed at Monsanto ( Lisbon ), this system is a simultaneous uplink/dowlink through 2 tranceivers ( UHF / HF ). This system was developed to enable DX comunications with any small UHF handheld tranceiver. To inform the user that the transmisson was received by the translator in good conditions, a response transmission at he same frequency that the user is was included. All the diagrams and schematics that will be showned here are parts of the full schematic of this system. Full schematic is available at the end of this page and are in PROTEL V2.0 format.

As you can see trough the block diagram it´s a very easy system and we will discusse each block at a time for you to best understand how it works and get an idea as how we builted up this thing .

Circuit description

The system is feed with 12V DC and has 2 separated regulators for 5V, one 7805 for the digital circuitry and one 78L05 that provides 5V only for the VOX interface, this was done to reduce digital switching noise and improve imunity for the 2 VOX´s. The clock frequency is around 16 Hz witch provides beacon speed, all timings required, syncronous switching times and also prevents unwanted VOX switching due to noise from RF that might activate the tranceivers squelsh. The audio from one transceiver is feed to the VOX and as soon as the other radio´s PTT is switched on a signal is sent to the other vox preventing acidental trigering of this vox due to digital and analog switching interference. Both radios are relay activated but an optocoupler was  also made available if circuit isolation is required. To simplify the explanation, only one channel will be explained since the other one is exactly the same.