Radio XTZ is one of the many hobby broadcast operations found on the Internet, with one difference - It also operates transmitters on the air! These very-low-powered, short range transmissions are authorized by the Federal Communications Commission under Part 15 of the Rules; specifically

Radio XTZ operates AM 640 and AM 540 under authority of Section 15.221 (47 CFR 15.221(a); carrier current operations),
and Stereo 100.1 and Stereo 105.1 under authority of Section 15.239 (47 CFR 15.239(a), (b), and (c))

While it may not seem like much, the AMs, due to the fact that the power lines run down an alleyway behind the houses for several blocks, actually get a respectable range - nearly a mile!

The FM signals manage to cover a roughly quarter-mile circle; just over two blocks.

Radio XTZ originates from a custom-built PC running Windows 2000 Pro with Service Pack 4 on a 2.4 GHz Pentium 4 CPU, 1.2 GB RAM, and a 120 GB Hard Drive through a DARLA24 pro soundcard.

The audio from StationPlaylist Studio Pro is run through an AudioArts A-50 eight channel broadcast board (six channels active), gently processed by an Orban Optimod 8000A for FM1 and an Optimod 8100A for FM2 and the stream, and a CBS Audimax/Volumax III for AM 640. AM 540 takes the same feed from the board, but has its own internal limiter circuitry.

Pictures ARE AVAILABLE!!!

A bit about the transmitters: AM540 is driven by a Radio Systems TR-20 solid-state transmitter; nominally 20 watts out. AM640 is somewhat older; it's an LPB RS25B (TUBES!) that actually manages to crank out more than 30 watts! AM 540 is coupled to the AC power lines by a special coupler circuit that isolates the 120 volt AC from the transmitters. AM 640 is feeding a somewhat novel “antenna”: It's a length of coaxial cable that's been “reversed”, and terminated at the far end; sort of a do – it – yourself version of Radiax®.

FM 100.1's transmitter is a custom kit-built unit with a nominal 10 watts out, that I have dialed back to about 1 watt or a bit less – and that 1 watt is fed into a fifty-ohm resistive load which is unshielded. This keeps the actual radiated signal within the FCCs limits I referenced above. FM 105.1 is running a “real” FM transmitter – an RCA BTE-15, capable of 15 watts out! It's also running into an unshielded dummy load, with the power adjusted to match FM 100.1's coverage. Thus, I'm reasonably sure they both meet the FCC's limitations mentioned above.

Please Stand By!
Regards, Radio Tom

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