Why do early Mods have a different tone ratio?

[uncommonsense]

I suspect there was a Modulator Control that directly preceded that (there was an image of a Modulator controller opened in Hawaii that looked more like a newer SiraTone controller than the MCP--which is very similar to the UltraVoice in appearance), but that's more of an educated guess on my part.

Modulators never used any EOWS* controllers, did they?

http://airraidsirens.com/forums/viewtop ... ght=hawaii

That thread contains the photo I was talking about. Its definitely not an UltraVoice/MCP. Nor is it a SiraTone controller, as seen in this thread:

http://airraidsirens.com/forums/viewtopic.php?t=7279

The controller on that Hawaii Mod definitely seems to be something intermediate (and yes, I know I said otherwise in the thread. I changed my thinking!)

[NanSiren]

Back in 2001, when we had the tornado hit Glenville, KTTC had a report that had one of Rochester's 612s doing this same tone combo.

Edit: Here's a vid I took from the newscast
http://www.youtube.com/watch?v=g3IWh7A5ZsY

[4th Harmonic Class-D]

I have both the MCP Controller & Ultravoice Controller schematics. The MCP controller uses Fairchild semiconductor ML2036 "Sine Wave" generator ic's & the Ultravoice uses Motorla semiconductor MC145220, "Dual Serial Data PLL Frequency Synthesizer ic", which is the one I have implemented in my system I have been building! With the Ultravoice, "Frequency Synth chip" ANY ratio/count time/frequency can be produced. I have noticed most ODD tone algorithms being due to technician program error. They are not easy whatsoever to program, even with a amateur knowledge in electronics & microprocessor/microcontroller programming. I caught hell for 9 months figuring the Ultravoice programming algorithm. Hope this helps!!!

' ' Ultravoice Tone Gen IC
http://www.freescale.com/files/archives ... umentation

' ' MCP Controller Tone Gen IC
http://pdf1.alldatasheet.com/datasheet- ... L2036.html