Hey,
Hey,
I’ve not bought any transmitter yet and the long goal is an AMT3000 (or AM88) but for starters I’m thinking of building a VEC-1290K. If after building it and monkeying around I really want to invest myself into LPAM, can I broadcast on two transmitters (different freq’s) from the same location or will they interfere with each other? How far apart would the antennas need to be? I believe I read that some particular transmitter chews up the surrounding frequencies with its square wave noise. Which transmitters would that apply to?
Will 2 transmitters interfere with each other?
I think I can offer some useful information on this subject.
One customer reported using two SSTRAN AMT3000s, one on 1650 and the other on 1700. The base loaded antennas were both mounted on the same 1 story metal roof and separated by only about 15 ft. He reported that it sounded like the audio was crossfeeding between the two signals. The audio from one transmitter was heard at a lower level in the other, and vice versa. After some dialog and some experimentation, he found the crossfeed problem was minimized to an acceptable level by PRECISELY tuning both transmitters. This is something you should do anyway even with a single transmitter.
I can only speculate, but I think, due to the close proximity of the antennas and the relatively small frequency spacing, the RF from one transmitter was “modulating” the RF from the other. Even though the Q of these antennas is fairly high, it isn’t high enough to reject the signal from a very close transmitter separated by only 50 kHz.
So the answer to your question is definitely YES, but try to separate the antennas as far as possible, and use frequencies that are far apart. The setup described above worked fine after careful tuning. I’m just making the suggestions to help minimize potential problems.
As for your last question, I am not aware of any transmitters that chew up a big chunk of frequencies due to square wave output. All part 15 transmitters employ a square wave input to the final RF stage, but the output of the RF stage is a sine wave due to the resonant antenna circuit. No matter how hard you hammer a resonant circuit with a square wave, you can only get a sine wave out. In fact, hammering it hard is better!
Phil B
I think I can offer some useful information on this subject.
Thank you for your useful input. I’ll go ahead and get started with a low cost (low expectation) kit, try to get a good signal then move on to the studio side of it – learn how to get a balanced sound into it and tweak the guts out of it for awhile.