Bleed Over From AM17 to AM19

[jcrmadden]

This weekend I heard a guy, "breaker, breaker one seven" for a radio check while I was on AM19.

He wasn't wiping the channel by any means (he was distorted and hashy), but I could hear him.

During a brief exchange with someone I could barely make out, he mentioned being in Wisconsin (his story to tell).

Assuming that's accurate, and he wasn't suffering from channel disphoria, how much power would he have to be pushing to cover at least five channels from 1000 miles off?

 

[prcguy]

It’s rarely the amount of power, it’s a combination of too much audio causing IMD in the transmitter coupled with an amplifier that is not linear or is run into saturation creating more IMD. You can put most CBs on a signal generator and run a big signal into them like 10dB over S 9 and two channels away the radio is quiet and happy. But the overdriven IMD laden idiot on CB is actually transmitting energy covering multiple channels at the same time. It’s not your receiver’s fault it’s the idiots dirty transmitter.

I’ve watched many of these garbage spewing stations key up and on a spectrum analyzer they can cover a dozen channels with modulated energy, the whole CB band will look like a Christmas tree going up and down with the guys voice.

 

[jcrmadden]

What is IMD?

 

[slowmover]

Ha! I was leaving out of Fort Worth one night going north up US-287 and was getting nearly wiped on AM-19 not that far from Wichita Falls.

Took me awhile as “it” was also on adjacent channels.

Found the offender with his ICOM/Yaesu on 22-LSB.

Him and his buddy denied it. Till I repeated almost verbatim what one had been saying.

A long silence followed.

.

 

[slowmover]

What is IMD?

Intermodulation Distortion.

Too many crayons at once.

https://www.thetechedvocate.org/what-is-intermodulation-distortion-imd/

 

[jcrmadden]

So when skip is rolling wide open and there's a hundred signals piled up...

When I start hearing the squeals, hums, and tones reverberate is this something similar to IMD or something different entirely?

 

[slowmover]

More than one thing.

Depends.

 

[KB4MSZ]

So when skip is rolling wide open and there's a hundred signals piled up...

It will all blow over by about 2030.

 

[prcguy]

So when skip is rolling wide open and there's a hundred signals piled up...

When I start hearing the squeals, hums, and tones reverberate is this something similar to IMD or something different entirely?

No, IMD is generated in a device or non linear junctions when enough RF is present. A diode is a non linear junction and corrosion between two metals like a rusted fence screwed to a metal pole can also create IMD in the presence of RF. Driving a transistor amplifter beyond its ratings can create IMD. IMD is like ghost signals that can interfere with reception and it can also show up as a raised noise floor covering up weak signals.