ICOM IC-A220 Transceiver...anyone have one?

[alcahuete]

Great to hear your credentials. I've been an FAA Manager for almost 15 years.

You're making my point for me. Light sport pilots do not need to use Part certified radios. In fact they aren't required to have a radio at all. That's why they can use the non-TSO version.

Icom did not originally design this radio to be used on board aircraft. Because is it being used outside of its intended use by sport pilots does not mean a thing.

 

[alcahuete]

You're still conveniently not reading the 2nd sentence. It is not that it CAN be used as a ground-to-air transceiver, that's how it was designed and marketed by Icom. It was not designed, marketed, or intended by Icom to be used aboard normal aircraft.

 

[N4GIX]

Okay, this is silly. Check out Chief Aircraft's listing for this series of radios:
Icom Base Station, Mobile and Air Transceivers - Chief Aircraft Inc.

1. is for mobile/base use $890
2. is for mobile/base with power supply $1,099.
3. is non-TSO'd version for aircraft panel mount $1,179.00
5. is the TSO'd version for aircraft panel mount $1,495.00

That is $316 strictly for TSO testing, paperwork, and recoup of certification costs.

If you were to open them up side-by-side and examine the components and schematics, they are 100% identical!

 

[alcahuete]

100% correct. Icom eventually sought certification. However, when it was designed, it was not intended for airborne operation as a primary VHF transceiver, which helps explain why they designed it to the absolute minimum required specs.

 

[krazybob]

We are talking about the concept of scanning while MONITORING aircraft when using for example an Icom A120 or an older A110. Scanning is what we do and if we're trying to listen to, for example, Ontario or LAX, or maybe even John Wayne, it helps to listen to the high altitude sector areas if you're looking to pick up an in-flight emergency. That's where scanner comes in handy.

With monitoring in mind, the choice of the receiver sensitivity, as well as any efficient and effective antenna become more important. We're not the FAA with a billion dollar budget.

This means that having the lowest receive sensitivity possible is important. When you buy a commercial rated radio you know it has the latest DSP and auto squelch capabilities and would make a superior receiver! Two channels albeit.
I agree with N4GIX that the units have not been deliberately "crippled." As we've discussed at length, general aviation for example generally flies between 2,000 feet and 8,000 feet. Oxygen or a pressurized cabin are required at 12,500 feet or greater.

At that altitude their communications range is considerable. Their power output rated in EIRP and is limited as is its receive sensitivity. That way the pilot is not likely to attempt to communicate with the station he cannot hear. Use the calculator I linked to below to calculate the range of an aircraft at a particular altitude.

Remember that it is cumulative. I live at 6,300 feet and if an aircraft at 10,000 feet over Madera County for example is fighting a fire our two areas have a crossover that allows me to hear that aircraft. Been there, done that, don't need the T-shirt.

One point made was that AM specifically is prone to skip and this is not true. Skip is based on the most usable frequency or the MUF. Skip is the process by which the radio signal goes up and hits the atmosphere and then comes back down it an equal but opposite angle. It often times repeats itself which is what allows long-range communications but generally not at these frequencies. The mode of operation such as AM vs FM is not affected by the MUF and the suggestion that one's range will increase.

However, depending upon the altitude being flown by the pilot, such as between two cloud layers, a phenomenon known as ducting may occur in which the radio signal travels in a tunnel created by the clouds. Ducting is caused in part by what we know as refraction, which adds approximately 20% more range to aircraft communications communicating just over the horizon. But this is not the norm. Aviation communications are generally restricted and range by power output, receive signal strength on the other end, and their altitude above ground.​

The conclusion that should be arrived at from this information would suggest that the purchase of a panel mount aircraft transceiver would be an excellent choice because of its internal construction as compared to a scanner. It may be limited to 1uV sensitivity which may be overcome by the use of a 20dB preamplifier.

One word of caution if you're doing this with a scanner is it will generally cause front end overload and you will hear more bleeps and bloops and FM radio stations from images than you knew ever existed. You would need to put in a bandpass cavity assembly before the preamp. I hope you've got Deep Pockets.

Radio Distance: https://tinyurl.com/radio-distance

Online Propagation: http://www.voacap.com/hfbc/

Ducting: https://en.m.wikipedia.org/wiki/Atmospheric_duct

 

[nanZor]

N4GIX - you hit it on the head - balanced is the keyword. So uber-sensitivity while obtainable, is not the primary objective.

Re the A24 - nice backup. I particularly like the user customizable audio frequency response depending on conditions. But at home and not on the tarmac, none of the settings sounds as nice as a simple Uniden 355C. imho. Hint: I probably sound like a broken record, but use the very narrow duck from the A24, the Icom FA-B02AR, on your normal scanners for a *true* vhf airband duck - you may see a nice improvement to the typically wide scanner front ends.

For simple monitoring, I'd put the money into antenna, feedline, and possible vhf passband filter to a decent scanner. The rest of the money you save can be put toward aviation fuel costs, rentals, and the occasional burger-runs. Or that pair of noise-cancelling headsets you've had your eyes on!

 

[N4GIX]

One point made was that AM specifically is prone to skip and this is not true. Skip is based on the most usable frequency or the MUF. Skip is the process by which the radio signal goes up and hits the atmosphere and then comes back down it an equal but opposite angle. It often times repeats itself which is what allows long-range communications but generally not at these frequencies. The mode of operation such as AM vs FM is not affected by the MUF and the suggestion that one's range will increase.

Radio Distance: https://tinyurl.com/radio-distance

Online Propagation: http://www.voacap.com/hfbc/

Ducting: https://en.m.wikipedia.org/wiki/Atmospheric_duct

I was actually referring to sporadic E-skip (ES), which while normally limited to the lower frequencies, can (and often enough do) extended into higher aviation frequencies to become a concern that design engineers must take into account.

Propagation: sporadic E skip (Es)

For instance, I can sometimes communicate with a fellow amateur operator on 2m AM from my home in Hammond, IN to his location in Madison, WI whenever ES conditions are occurring. Sometimes I can even each an FM repeater in Detroit, MI...

BTW, none of the links you provided are working for some reason. In any case, I will now bow out of this thread as it has drifted way too far off course...

 

[krazybob]

I was actually referring to sporadic E-skip (ES), which while normally limited to the lower frequencies, can (and often enough do) extended into higher aviation frequencies to become a concern that design engineers must take into account.

Propagation: sporadic E skip (Es)

For instance, I can sometimes communicate with a fellow amateur operator on 2m AM from my home in Hammond, IN to his location in Madison, WI whenever ES conditions are occurring. Sometimes I can even each an FM repeater in Detroit, MI...

BTW, none of the links you provided are working for some reason. In any case, I will now bow out of this thread as it has drifted way too far off course...

I fixed the links.

Sent from my SM-G965U using Tapatalk

 

[krokus]

... from my home in Hammond, IN ... Sometimes I can even each an FM repeater in Detroit, MI...

Sorry to add to the drift, but I curious which repeater?

Sent using Tapatalk

 

[krazybob]

In my opinion based on years working with radio and detaining a high-level license the sensitivity of a ground base station should not be limited to 2uV. A ground based station should have maximum sensitivity because they will be using a compromise antenna to begin with.

An aircraft at altitude has no obstructions and their signal will travel for quite some ways. Even the FAA recognizes that their ground-based received is limited by terrain in many cases and has strategically placed located long-range sector repeater sites SO THEY CAN HEAR. This defeats the purpose of limiting everybody else is radios. Commercial aviation uses computers for much of what they do these days.

In essence what I am saying is that if somebody wants to buy a more professional radio for reception look at an Icom A120 even though it has a 1uV sensitivity.

On a side issue, I don't know why years ago Aviation didn't slowly convert to FM. FM is less prone to interference.

Sent from my SM-G965U using Tapatalk

 

[N4GIX]

On a side issue, I don't know why years ago Aviation didn't slowly convert to FM. FM is less prone to interference.

Aviation voice radios used VHF AM, from the beginning simply because it was a lot less expensive than FM at that time. Over the many decades, the sheer number of aircraft with perfectly serviceable AM equipment pretty much has made the wholesale changeover from AM to FM impractical. Further exacerbating the problem would be the expense of having to maintain "dual systems" for some number of years during a "transition phase."

On the purely technical side AM is used so that multiple stations on the same channel can be received. (Use of FM would result in stronger stations blocking out reception of weaker stations due to FM's capture effect*). Aircraft fly high enough that their transmitters can be received hundreds of miles away, even though they are using VHF. There have been hundreds of instances where "Mayday" or "Pan Pan" calls have been heard underneath another transmission, whereupon the receiving station would quickly acknowledge the emergency call. Such very likely would not have occurred had FM been in use.

*Nota Bene: Capture effect - Wikipedia

 

[N4GIX]

Sorry to add to the drift, but I curious which repeater?

KE8HR repeater information on 146.760 in Detroit, Michigan by artscipub.com

 

[zz0468]

The reason aviation receivers are seemingly less sensitive than FM receivers is simply that they don't need to be more sensitive. FM, by it's nature, has noise reducing properties. Natural noise is mostly AM in nature, so a detector that almost completely ignored it can rely on a low noise figure to set the signal to noise ratio.

Noise is cumulative, and one major source is just environmental noise. Black body radiation from the earth, trees, electrical noise, sun noise, etc. all adds up. An FM receiver is mostly immune to it, but an AM receiver is not.

If you had an FM receiver with 0.2uv sensitivity, you can use most of that to recover a weak signal out of the mud because an FM detector just doesn't respond to the AM characteristics of natural noise. An equivalent AM receiver would just deliver more noise to the speaker, and below a certain threshold, system noise temperature is more heavily influenced by the environment, not receiver sensitivity. The signal to noise ratio is set externally to the receiver, and a more sensitive receiver simply can't improve things.

If you have an AM receiver with .1 or .2 uv sensitivity and a yagi antenna, you can aim it at the ground, the sky, the sun, or a tree, and hear the noise level change. In an aircraft environment, that sort of behavior isn't helpful.

 

[zz0468]

BTW, I have several Motorola CM200 aviation band receivers on both VHF and UHF air bands. These are government/military ATC class receivers that came out of FAA facilities. They are spec'd at about 1.5 uv for 6db s/n.

The air band radios in civilian hands are as good as they need to be.

 

[zz0468]

On the purely technical side AM is used so that multiple stations on the same channel can be received. (Use of FM would result in stronger stations blocking out reception of weaker stations due to FM's capture effect*).

This is quite correct. FM capture effect is nice in LMR service, but even if it's unintelligible, air traffic controllers need to be able to tell if another aircraft got stepped on.

I've also heard that there are phase distortion issues with FM operation on high speed aircraft, most likely relating to Doppler shift. AM is more tolerant to off frequency operation than FM is. The Doppler shift is still there, it's just not banging the modulation envelope against the sides of the IF filters.

 

[KevinC]

I think we're done here.