Old radios

Tom-D

Taxi to Parking
Joined
Feb 23, 2005
Messages
34,740
Display Name

Display name:
Tom-D
To train a new student, do you need a radio with the third digit past the decimal point?

many of the airports now have frequencies that can not be received by many old radios.

Thoughts?
 
To train a new student, do you need a radio with the third digit past the decimal point?

many of the airports now have frequencies that can not be received by many old radios.

Thoughts?
Is it a 360 or a 720/760 radio? I am not sure if a 360 channel radio is still legal.

But...

I guess the bottom line is that if the radio is legal, one can work around the lack of frequencies.
 
To train a new student, do you need a radio with the third digit past the decimal point?

many of the airports now have frequencies that can not be received by many old radios.

Thoughts?
Many older radios only display 2 decimal points, the last one is implied. For example:
118.00 = 118.000
118.02 = 118.025
118.05 = 118.050
118.07= 118.075
118.10= 118.100
etc.
Are you sure you aren't using one of those radios?

If the plane really has only 360 channels, there are other issues- you may get interference on the frequency you are listening to if someone is is transmitting on an adjacent channel. Transmitting on a 360 channel radio is legal so long as it meets a 30 ppm frequency tolerance, but most don't meet that standard. See: https://www.fcc.gov/wireless/bureau...ion/aviation-radio-services/aircraft-stations.

The cited reference suggests that isn't easily done:
The only way to bring a unit into compliance is through the installation of an FCC type accepted "upgrade kit," which may be available from the unit's manufacturer. Like the radio itself the upgrade kit will have an FCC ID number that may be verified against the FCC Aircraft Radio List. Presently, however, few manufacturers offer FCC type accepted upgrade kits. If a kit is not available for a particular model of radio, the radio may not be adjusted and used for communications purposes on board an aircraft. If no kit is available, the radio may be reinstalled in the aircraft so long it is not intended to be used to transmit radio signals.
I would guess that the radio would be much more difficult to upgrade now.
 
A 360 channel radio is still legal if it meets the frequency tolerance requirements. All 720/760 channel radios do, some 360 do, many 360 don't.

As CJack points out, it's not the numbers behind the decimal points but whether your radio can tune the 25 KHz channels or not, regardless of whether it uses 2 digits, 3 digits, or just flipping a switch to indicate the odd-numbered channels.
 
FWIW most newer radios have stuck mic switch protection, preventing stuck mic from blocking a frequency for more than xx seconds.
 
Is it a 360 or a 720/760 radio? I am not sure if a 360 channel radio is still legal.

But...

I guess the bottom line is that if the radio is legal, one can work around the lack of frequencies.
I still have FCC PMA for a 2 channel and a 6 channel, so I'm not sure why a 360 wouldn't be legal if it met the frequency accuracy required.
 
KX 170-B is a 720 channel radio but has no third digit 000.00 is all that they have,, many of the airports have 000.000 frequencies.
The CFIs argument was he can't send a student to any airport that has the third digit as their Common traffic freq. or if on a solo cross country if the student has a problem they would be restricted as to where they could divert.
Most all the weather stations around here are 000.000 type.
 
I still have FCC PMA for a 2 channel and a 6 channel, so I'm not sure why a 360 wouldn't be legal if it met the frequency accuracy required.
We know the 360s have gone away, this isn't about frequency separation.
 
KX 170-B is a 720 channel radio but has no third digit 000.00 is all that they have,,
That's what was described in Post #3 above. Dial a KX170/KX175 to 119.62, for example, and it is actually tuned to 119.625. If the second decimal place is a '2' or a '7', then the third decimal place, though not shown on the display, is always a '5'. I'm still using one of those radios.
 
That's what was described in Post #3 above. Dial a KX170/KX175 to 119.62, for example, and it is actually tuned to 119.625. If the second decimal place is a '2' or a '7', then the third decimal place, though not shown on the display, is always a '5'. I'm still using one of those radios.
Thanks, I didn't realize that. you can't see it on the dial.
 
KX 170-B is a 720 channel radio but has no third digit 000.00 is all that they have,, many of the airports have 000.000 frequencies.
The CFIs argument was he can't send a student to any airport that has the third digit as their Common traffic freq. or if on a solo cross country if the student has a problem they would be restricted as to where they could divert.
Most all the weather stations around here are 000.000 type.
If that statement above is being shared accurately here, the CFI is giving bad information. A 720 channel radio and pick up anything in the USA. Europe is a different matter, but not pertinent to this discussion. People still learn to fly and solo with a 720 channel radio with only 2 decimal places displayed. Better that the CFI teaches their students about the radio in the planes they fly, and other radios they may encounter, than give poor information.


We know the 360s have gone away, this isn't about frequency separation.
The people trying to help you were confused by your original post (requoted below). We figured you weren't talking about the still older 90 channel radios. As mentioned above, the 720 channel radios can work with any USA frequency, and many of them are pretty old now. The bolded part of your question was the part that made us also think you may have been discussing a 360 channel radio.
To train a new student, do you need a radio with the third digit past the decimal point?

many of the airports now have frequencies that can not be received by many old radios.

Thoughts?
 
you can tell who the haters are.

Like I'm your avionics expert.
 
If that statement above is being shared accurately here, the CFI is giving bad information. A 720 channel radio and pick up anything in the USA
Nope, while many of the upper channels are marked out for future UNICOM / AWOS use, they do have ATC up on some of them. I've been assigned those channels (ATC even asked me if I could tune that... I pointed out the Navion is old but it has up to date avionics).

Europe is a different matter, but not pertinent to this discussion. People still learn to fly and solo with a 720 channel radio with only 2 decimal places displayed. Better that the CFI teaches their students about the radio in the planes they fly, and other radios they may encounter, than give poor information.
Europe has even gone beyond 760. They are using 8.33Khz spacing.

the 720 channel radios can work with any USA frequency, and many of them are pretty old now.
Again, incorrect.
 
If I recall correctly, in order to get the .025 and .075 frequencies, you need to pull the smallest knob out and then turn it. Like others have said, the .005 won’t display
 
If I recall correctly, in order to get the .025 and .075 frequencies, you need to pull the smallest knob out and then turn it. Like others have said, the .005 won’t display
That is true on some radios, but not the KX170/175 series. The small knob just clicks through .00[0], .02[5], .05[0], .07[5], .10[0], .12[5], .15[0], .17[5], ...
 
Last edited:
Nope, while many of the upper channels are marked out for future UNICOM / AWOS use, they do have ATC up on some of them. I've been assigned those channels (ATC even asked me if I could tune that... I pointed out the Navion is old but it has up to date avionics).

<SNIP>

Again, incorrect.
Thanks for the correction. I actually saw that earlier when looking up the frequency tolerance I mentioned earlier. However, one can certainly still train and solo in a plane that displays only 2 places past the decimal point, and that part of my statement still stands.
This radio could be bought new, and I presume has 760 channels, but only displays 2 decimal places: http://sarasotaavionics.com/avionics/par200a

Assuming @Tom-D relayed the conversation accurately, the CFI is still incorrect.

Europe has even gone beyond 760. They are using 8.33Khz spacing.
True, but I doubt the training mentioned in the OP will happen there. I wonder why- they don't have the traffic we do.
 
Back
Top