Post by Deleted on Apr 6, 2013 16:29:26 GMT
Most part 15 transmitters get fed by an audio cable coming from the audio source, but sometimes a station will use an STL, a studio-transmitter-link, using an FM channel to transport audio to a distant AM transmitter/antenna location.
For awhile I've been sending audio using a Wholehouse 2.0 at 107.1 FM sending audio to two different AM transmitters in two separate locations. It took quite a while to get the right combination of antennas so that this arrangement finally became stable and reliable.
But then I read in a radio discussion blog that a translator CP (construction permit) was issued for 107.3 with 250Watts, to be located within a mile of my location! And yes, last night I already heard it, coming in with equal power on my spectrum analyzer as my own signal. One of my FM receivers was getting bleed-over from this adjacent channel, so I said to myself, "We must accept interference. We cannot cause interference."
A new frequency search began.
Using radio-locator.com I made a chart of the local FM band showing geographic locations of antennas, power levels, and frequencies of everybody. The FM dial is crammed.
When I'd found a spot where I might be able to wedge in, I looked at it on the spectrum analyzer. There was a neat opening just waiting for me.
Everything was re-tuned, re-tested, and today we have a better STL than we did before.
But eventually the plan is to say goodby to the FM band, as we follow the example of Tha Dood, a part 15 man who uses 49mHz for his STL. That is the next goal.
For awhile I've been sending audio using a Wholehouse 2.0 at 107.1 FM sending audio to two different AM transmitters in two separate locations. It took quite a while to get the right combination of antennas so that this arrangement finally became stable and reliable.
But then I read in a radio discussion blog that a translator CP (construction permit) was issued for 107.3 with 250Watts, to be located within a mile of my location! And yes, last night I already heard it, coming in with equal power on my spectrum analyzer as my own signal. One of my FM receivers was getting bleed-over from this adjacent channel, so I said to myself, "We must accept interference. We cannot cause interference."
A new frequency search began.
Using radio-locator.com I made a chart of the local FM band showing geographic locations of antennas, power levels, and frequencies of everybody. The FM dial is crammed.
When I'd found a spot where I might be able to wedge in, I looked at it on the spectrum analyzer. There was a neat opening just waiting for me.
Everything was re-tuned, re-tested, and today we have a better STL than we did before.
But eventually the plan is to say goodby to the FM band, as we follow the example of Tha Dood, a part 15 man who uses 49mHz for his STL. That is the next goal.