Could this have been a legal conversation on this band?

Just for fun, I picked up a cheap Chinese Ebay Airband (118-136) receiver.

I know it does what it is supposed to do sometimes, as I've picked up tower traffic, but I just picked up a civilian conversation. The tuning dial has no numbers, so I have no idea exactly where I was. It was somewhere near the middle.

It sounded like a million other repeater conversations that I've heard, except I only heard one side. I couldn't make out a ton the words, but at some point, the guy was talking about his radio equipment.

At first I thought maybe some people were illegally using one of the airband frequencies, but I was unable to find the conversation with a better radio, as I scanned through 118-136, so now I am suspecting that this was happening on a different frequency and something buggy about the radio had it picking it up.

The other odd thing was that it sounded like a shortwave LSB conversation when I was a few clicks off, as there was too much bass in the voice and it was too slow.


A few questions:

Is it legal for any civilians to use anything between 118-136?

Assuming no, is it much more likely that the radio picked up a different frequency, than people pirating that band?

Thanks

cheap Chinese Ebay Airband (118-136) receiver.

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...with no warranties expressed or implied, especially when it come to filtering, selectivity, image and adjacent channel interference! Unfortunately you're at the mercy of any strong signal that comes down the antenna and will break through into the amplification stages and hence out of the speaker - as you surmised it could be any local signal that a better radio would reject.

There plenty of unofficial and official chat frequencies in the airband, although mostly in your area you would be more likely to pick up the company frequencies - pilots would be rather busy in your area to spend time lazily chatting on the unofficial 123.45MHz chat channel.

Could well be a ham on his 80 or 40m band chatting to his mate on sideband breaking through into your radio - I doubt if you'd get anything sensible out of a 2m transmission in NFM.

...and it's a no-no for Joe Public to transmit in the aircraft band, a lot of towers have very good DF equipment although someone would have to alert them to the frequency in use - expect the men in the blacked-out SUV's to come calling soon though!

Probably slope detection of a two meter ham conversation received as an image frequency. That would account for both the content and the poor audio quality.

Yeah most likely 2 meters. Though a few weeks ago I did see people a pair of those Icom A24 Aviation handhelds to chat across downtown. Very odd find but than again a lot of people just use anything they get their hands on unaware that the FCC has regulations.

Thanks for all of the replies.

I had a feeling the radio (cheap Chinese Ebay Airband (118-136) receiver) might have been a little funky, but I wanted something new to play with.

dragon48 said:

Thanks for all of the replies.

I had a feeling the radio (cheap Chinese Ebay Airband (118-136) receiver) might have been a little funky, but I wanted something new to play with.

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Cheap little airband radios can be fun, but remember, selectivity, accuracy, and image rejection all cost money. You've learned why cheap radios are cheap.

you could try

scanning the 144 to 148 ham band at the same time and see what happens.

wtp said:

scanning the 144 to 148 ham band at the same time and see what happens.

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Ty - I'll do than next time I pick up this kind of signal with the radio.

Most likely the receiver is dual-conversion, with a first IF of 10.7mhz with poor rejection.

Without getting too far into high or low side injection etc, just double the IF frequency, and add or subtract it to your display frequency.

Example (even though your rx doesn't have a dial) - let's choose 124.000 as your display frequency:

124.000 + 21.4 = 145.700 mhz. 145.700 is in the 2m amateur band.

Costlier dual-conversion receivers increase the 1st IF rejection.

Although probably not practical in your situation, an external airband bandpass filter, like the AOR ABF128 (or par etc) could cut down on this.

If you're only hearing one side of a 2m conversation, then it's probably not via a repeater (to you). Either the station is on a simplex frequency and the other end is too far away, or you're getting a transmission from a nearby station on a repeater input. When checking 2m frequencies, look at simplex and input channels and don't waste time on the repeater output subbands.