High freqs on Collins nav unit
 

Hi!

In some of our aircraft and on some Collins NAV/LOC/ILS units we're able to tune VHF NAV freqs up to 136Mhz. First it's the normal 108-117ish, but if you continue to twist the knob is starts on 135(?) and goes on to about 137 before it starts at 108Mhz again.

I've heard about special Australian VOR's, but does anyone know about this function, and if, any use?

rgds

Remote tuning radios sometimes have Gables (tuning) heads installed that do not reflect what the remotely mounted receiver is capable of...occasionally frequencies are indicated but not able to actually be tuned, only selected.

I've encountered one of these on an aircraft where the NAV/LOC/ILS and VHF Com was normally tuned by Remote Tuning Units or via the FMC. One emergency unit (gathering cob-webs) was available in case of RTU or FMC failure to directly tune both Radio-Nav and VHF Com, what you got (Nav or Com) depended upon what frequency you set.

PERHAPS the unit/s you refer to are of the same basic 'off the shelf' Collins stock, but without the Com facility. As 411A suggests, you may only be getting a nice number display without any function above 118.0