CDF 151.2725, or did I miscopy it?

[CZ]

On one of the CDF frequencies heard them refer to 151.2725 being used for Air Tanker work on a fire east of Fresno.

However, when I programmed it into the Bearcat 785D, it came up 151.2750. So, I was wondering, did I just hear the frequency wrong when I wrote it down?

Could hear "AirTac" and the aircraft he was directing the drops for.

 

[SAR923]

It seems that CDF has started use some of the new narrowband frequencies and I believe that this is one of them. The 785 only does wideband FM on VHF but the front end is wide enough you should still be able to hear the traffic on the narrow band frequency.

 

[northzone]

CDF New Narrowband channels in use

I found a license for all the CDF mobile frequencies, KA3134. You guys are right, two new frequencies 151.2725 and 151.2875, narrowband emission 11k2F3E.
TCU was using the first one today for Air Tacitics on a wildfire.

 

[CZ]

Found I could program 151.2725 in by using "Steps" 7.5 KHz.

 

[CZ]

Hmmm, programmed 151.2725 in using the 7.5 KHz split in the 785D, but on FM, & NFM, audio is scratchy, occasionally hard to understand. Far as I know, this is a repeater -- anyone know for sure if it is?

 

[SAR923]

The spec sheet for the 785 doesn't show NFM in the 151 range. I could be wrong but I suspect you're still receiving FM even though you've programmed the split frequency. This is a repeater frequency so it should come through loud and clear on NFM unless you're just too far away to get a good signal.

 

[northzone]

This is a repeater frequency so it should come through loud and clear on NFM unless you're just too far away to get a good signal.

This is not a repeater frequency, it is simplex unit to unit (aircraft to aircraft in this case).

 

[jwpottberg]

CDF historically has had 3 Air Tactics simplex frequencies aligned on the existing 15 kHz bandplan:

151.2800 - AirTac 4 (old "Blue")
151.2950 - AirTac 5 (old "Green")
151.3100 - AirTac 6 (old "Yellow")

They have added two more that are on the new 7.5 kHz splits, also simplex:

151.2725 - AirTac 7
151.2875 - AirTac 8

They are narrowband transmissions and, hopefully, so are the old ones now (otherwise they would bleed over to the new ones). I think only the latest Unidens have the receive circuitry selective enough to prevent reception of an adjacent 7.5 kHz signal.

Jim

 

[digitaljim6]

The Air Tactics 7 and 8 designations for the two new narroband channels were recently changed to Air Tactics 21 and 22. This was done to minimize user confusion between the existing wideband channels and the newly added narrowband ones.

Another year or two and the equipment will all be narrowband so it won't matter.

So, it's Air Tactics 4, 5, 6, 21 and 22.

 

[CZ]

Over the last week or so I've been hearing traffic on 151.2725 that judging from signal strength is going through a repeater. Signal of both people talking reads virtualy the same in strength on the 785D's meter.

 

[digitaljim6]

You are probably hearing a Command 1 151.2650 repeater since it is only 7.5 KHz away and "wideband".

Make sure you are programming 151.2725 using 7.5 step so that the frequency reads 151.2725, and that the mode is FMN. This will let you hear 151.2725 correctly,

BUT

you will probably continue to hear scratchy Command 1 transmissions when listening to the new 151.2725 channel until the Command 1 repeaters go narrowband.

 

[digitaljim6]

OOOOPS!

Where I wrote "Command 1", change it to read "Command 2".

 

[Ben96cal]

Air tac 8 change

Air tactics 8 is actually 131.5750 now. It is used frequently in Norcal.

 

[digitaljim6]

Ben96cal,
Really? The official documentation I've seen designates only VHF-AM aircraft channels as "Victor" channels and only FM channels as "Air Tactics". Maybe that's changed. What's your source?

 

[Ben96cal]

CDF

my source would be my ears. heard it used on a fire couple weeks back referred too. new freqs below.

air tac 8 131.475
air tac 9 131.575

 

[digitaljim6]

Interesting - a CDF aircraft used that designation?

 

[Ben96cal]

CDF

yes

 

[digitaljim6]

ok - I'll listen for others.