Before I bought a dstar system I took a pair of GE Phoenix SX mobiles and made a back to back repeater - It would work AOK if I hard keyed the transmit radio and left it keyed. The time it took the synthesizer to load and the transmitter to settle caused leading data loss. I did have to do a data inversion taking discriminator audio thru an emitter follower stage, then direct coupled to a common emitter stage and to the VCO modulator stage (after audio filtering). A CCD delay IC between the RX and TX may have helped - also a crystal controlled TX may have been faster on key up. I also could have left the TX keyed and switched a later stage in the TX chain.
That said, as a repeater it simply repeated what was present on the input - no DCD - just COR to key - I don't know how this would work in a bidirectional application where you carry data from the repeater to the fill in area, then turn around and carry data from the fill in area back to the repeater site. Seems like the time needed to load the syn and switch between send and receive would kill the thing - not trying to rain on your parade, but there may be some challenges. Best success, Steve NU5D Tony Langdon wrote: > At 01:00 PM 11/24/2008, you wrote: > >> I have tried it several times and could not get it to work. I think >> that the delay between keying up the dstar radio and the FT-8800 >> repeating the signal is too great the fully relay the data packets. >> > > Seems the best hope for a quick and dirty repeater/range extender is > to get a couple of suitable (i.e. not PM ) commercial radios, modify > them and connect them back to back so they will pass GMSK. :) Just > have to make sure the repeater doesn't distort the signal or take too > long to key up (and lose the headers). > > 73 de VK3JED > http://vkradio.com > > There is more to amateur radio......
