Transmitting on 121.5 as a bonus

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Code90

Pre-takeoff checklist
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Code90
I was told the other day while talking to ground at CHS (121.9) that I was transmitting on 121.5 at the same time.

Had COM1 (from G530) set on 121.9 and active / lit on my GMA 340. Had COM2 unlit (from G430) and set on ATIS freq 124.75. Is this likely from some type of bleed over on the freq? Any thoughts of if this is something simple? Have never had any issues with transmitting or receiving. Never have been told that elsewhere. Is it worth throwing $ away chasing it?
 
Your transmitter could be spectrally "dirty" throwing "whiskers".

Or they could have had a local IMD mix happening on their end.

I think I'd start with easy and cheap.

Call them on the phone and set up a time to test to see if you can reproduce it again.

If it isn't reproducible then it's likely a non-issue.

Grab a handheld and park it on 121.5 and listen yourself while you do the test. Note: Turn the volume down, so the audio from the handheld doesn't go into your mic. Better yet, use an old fashioned ear plug under your headset for it.
 
In addition to what Nate wrote, in general, the ability of radio equipment to separate one channel from another can be degraded when the transmitter and receiver are very close together, or when the frequencies are close together. (There is no such thing as perfection in the design of electronic equipment; the closer you try to get to perfection, the more it's going to cost!)

In Civil Air Patrol, we often make use of this fact when searching for an ELT, by tuning the receiver to an adjacent channel when we get very close to it. That makes it possible to hear the ELT at reduced volume (and reduced signal-to-noise ratio), which makes it easier to hear variations in signal strength as we get nearer to or farther from it.

121.9 to 121.5 is a fairly wide frequency spacing, though.
 
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Could definitely be intermod. 121.9 - 121.5 = 400KHz. Any chance there's an NDB around with close to that frequency? Actually, there does seem to be the DYB beacon at 365 KHz.

We used to have fun putting up repeaters in Baltimore where the input and output were separated by 600KHz (and we had WCAO on that frequency).
 
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flyingron said:
Could definitely be intermod. 121.9 - 121.5 = 400KHz. Any chance there's an NDB around with close to that frequency? Actually, there does seem to be the DYB beacon at 365 KHz.



We used to have fun putting up repeaters in Baltimore where the input and output were separated by 600KHz (and we had WCAO on that frequency).
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Frogging 600 KHz split on Ham VHF is sooooo stupid. Fought a lot of problems over the years caused by that stupidity.
 
Next time, check from a different part of the ramp. if you were very close to their 121.5 antenna, it could have been overloading their receiver. Just move somewhere else and try again.

At one of my local airports, there is a specific spot on the ramp where you can hear the AWOS frequency coming over your radio which is tuned to the UNICOM frequency. You move just a few dozen feet away and it's back to normal.

The frequencies are not particularly close, either. UNICOM is 122.7 and the AWOS is 120.975.

Radios are funny that way.
 
flyingron said:
Could definitely be intermod. 121.9 - 121.5 = 400KHz. Any chance there's an NDB around with close to that frequency? Actually, there does seem to be the DYB beacon at 365 KHz.

We used to have fun putting up repeaters in Baltimore where the input and output were separated by 600KHz (and we had WCAO on that frequency).
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Or a transmitter on 122.3 or a couple of other frequencies.

The FAA frequency measurement folks are usually pretty good about this, but the possibility exists if the equipment isn't well maintained.

The question I would ask first is whether they hear it when other people transmit on 121.9 - if so it's on their end.

It would be a quick diagnosis on your plane if someone has a spectrum analyzer or high-quality tunable receiver.
 
ARFlyer said:
"This is Delta XXX calling for America XXX"
"On Guard"
"ON GUARD"
"This is Delta XXX ON GUARD calling for America XXX"
"ON GUARDDDDDDDD"
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Work work work....

And woe to the person who tries to chastise these jokers.
 
I heard a Citation transmit his whole plan the the "FBO" once he was to land on 121.50 this morning.

Someone yelled, "hey, you're on guard, buddy."

He couldn't quite understand what the other pilot said so he repeated his whole plan, on guard.

:rofl: Oh boy, the responses he got after that were damn funny.
 
Cpt_Kirk said:
I heard a Citation transmit his whole plan the the "FBO" once he was to land on 121.50 this morning.

Someone yelled, "hey, you're on guard, buddy."

He couldn't quite understand what the other pilot said so he repeated his whole plan, on guard.

:rofl: Oh boy, the responses he got after that were damn funny.
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I assume you're meaning some sort of "plan" for what they were going to need at the FBO and what not, and not a flight plan?

Would have been quite funny if someone would have just read it back and said "We'll have it all ready for you, Captain!"

And then... It wouldn't have been.

I know, I know. I've got a mean streak in my humor. Haha.
 
denverpilot said:
I assume you're meaning some sort of "plan" for what they were going to need at the FBO and what not, and not a flight plan?

Would have been quite funny if someone would have just read it back and said "We'll have it all ready for you, Captain!"

And then... It wouldn't have been.

I know, I know. I've got a mean streak in my humor. Haha.
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I don't remember it verbatim, but it was something along the lines of time until they arrive, # of pax, who's getting off and who's staying on, that they're going to grab a crew car to grab some food, how much fuel they think they would need (lol), where they're going to next, and some other mundane stuff.

Speaking of which, that reminds me of another situation I heard on guard - a regional guy was trying to call Ops on 21.5. "Ops, this is ASQ5473." It was quiet for a second, then a "female" voice came over saying, "go ahead." So, he started rattling off just a laundry list of things.

When he finished, you heard about 10 different people, all stepping on each other, just giving him an earful for about 60 seconds. Then some jokesters came on. Then the jokesters and the guard police went at it for a little. Eventually, things settled down and all went quiet again.

I think he got the frequency right the second time around.
 
Cpt_Kirk said:
Speaking of which, that reminds me of another situation I heard on guard - a regional guy was trying to call Ops on 21.5. "Ops, this is ASQ5473." It was quiet for a second, then a "female" voice came over saying, "go ahead." So, he started rattling off just a laundry list of things.

When he finished, you heard about 10 different people, all stepping on each other, just giving him an earful for about 60 seconds. Then some jokesters came on. Then the jokesters and the guard police went at it for a little. Eventually, things settled down and all went quiet again.

I think he got the frequency right the second time around.
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LOL I was flying for ASQ and heard stuff like that many times. It was hell for awhile after he/she finished transmitting, like you said. I once did the arrival PA on ATL approach frequency and when I finished the controller (his name was Smiley for those who remember him) said "(call sign) thank you for that totally useless information". I looked over at the Captain and he was doubled over laughing.
 
mscard88 said:
LOL I was flying for ASQ and heard stuff like that many times. It was hell for awhile after he/she finished transmitting, like you said. I once did the arrival PA on ATL approach frequency and when I finished the controller (his name was Smiley for those who remember him) said "(call sign) thank you for that totally useless information". I looked over at the Captain and he was doubled over laughing.
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I used to work ramp control for 3 and 4 at ATL. I've heard a few PA's... during a push...

Even have one recorded! lol
 
Cpt_Kirk said:
I used to work ramp control for 3 and 4 at ATL. I've heard a few PA's... during a push...

Even have one recorded! lol
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Yeah it's all those damn buttons and switches they have up there! :yes: :rofl:
 
mscard88 said:
Yeah it's all those damn buttons and switches they have up there! :yes: :rofl:
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I've told ramp my life story once after the ptt got stuck. It took a crew from the neighboring gate to get our attention. :D:rofl:
 
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