[ICOM] Icom IC-208

[William Lambing]

Mac, ICAO spent over 5 years coming up with the 8.33khz spacing.  They thought about 12.5 (which would seem logical....!) but opted instead for 8.33.  This really screwed up manufacturers of comm radios for airplanes, as you could imagine.  That also meant that the older mechanical units were ... out..!  We could not make a mod for the mechanical ones.  Digital controls however were ... able to be accommodated, albeit it was not easy.  Starting from scratch would have been better, but when you have thousands of digital controls (Collins, Honeywell, Bendix and others) starting over was not an option.  However, for new radios coming on line, new design was not that big of a deal.  Plus, with the advent of digital "stuff" for comms, this gave us (and others) the option of making the control head functional for the new digital modes.

ICAO did "their thing" to the Comm controls as they did with their "requirement" for Collision Avoidance, aka TCAS/TCAS-II (or ACAS as some call it) and the new RVSM (Reduced Vertical Separation Mode).

The US is still 25khz for Comm spacing on the VHF spectrum.  When the UHF end will change, who knows.  Only ICAO, but they do not control the military end of things...fortunately.

73

Bill, W0LPQ
Collins Avionics Field Service, Retired