CB carrier only, no modulation (intermittent)

[erkmann]

2009 GW1800, Sena 50S linked to Sena Freewire, added OEM CB, never fails to receive signal but oftentimes transmits carrier only. TX light appears to go on with every push of PTT. Transmission out/in on cell phone is fine. Because CB system is 100% reliable on RECEIVING, seems to me like issue would be in the handlebar PTT. Tons of contact cleaner has been used, though might not be getting into switch internals. Considering disassembly/replacement of switch. Thoughts? Thanks in advance.

[Rambozo]

That the TX light comes on and it transmits a carrier, means the PTT switch is obviously working fine. Either the mic audio signal is not making it to the radio or there is a problem with the modulation circuit. Does the intercom work?

[erkmann]

I have no wired headset so no idea how to check intercom. Audio out via cell phone works fine.

[erkmann]

Any connectors encountered during install were cleaned w CRC Electronic cleaner and brushed w dielectric grease. Again, this bike was ridden for 24 years w/o CB.

[Rambozo]

I believe audio to your cell phone doesn't pass through the Honda electronics at all. Straight from headset to phone via BT. That is why I asked about the intercom. It is the only other thing on the bike that uses the mic. Trouble shooting this will most likely require at least one wired headset, or the skills and equipment to do signal tracing.

[kwthom]

...but the audio to and from the bike *does* go to the Sena Freewire, which is then connected when the PTT button is used.

[Rambozo]

...but the audio to and from the bike *does* go to the Sena Freewire, which is then connected when the PTT button is used.

The question is, does it? The audio goes from the bike to the Freewire ok, but without the CB or the intercom, there is no way to confirm it is going to the bike. The headset signal is sent over BT just fine, as the phone works, but without testing at the Freewire and where it connects to the bike, no way to be sure mic audio is getting to the bike.
Without a wiring diagram, I'm not sure if the PTT switch is a single or multi contact unit, but the passenger PTT is only 3 wires. Most CBs do all the heavy switching inside the radio and the PTT switch is just for signaling.
Tracing it is pretty straight forward, with a tone generator and an O-scope, but without that, swapping in a corded headset could help testing via the intercom. If that works fine, the problem is likely in the CB. If the intercom doesn't work both ways, what works and what doesn't could help point to the problem.
It could be something as simple as a pin pushed back in a connector when it was plugged in.

[erkmann]

Thanks for all of this, guys. I’ll pull the Freewire and try a wired headset to see what we learn.

[erkmann]

Removed the Freewire, connected a conventional wired helmet, and went riding. All issues of '...carrier only, no modulation' resolved. Now, where might I find the problem when I go back to the Freewire/Sena 50S? What did we learn from this experiment?

[Rambozo]

That it works with a wired headset points to no audio getting from the freewire to the bike. Initially I would say there is a problem with the freewire unit.
Next try the intercom between the freewire and the wired headset. See if there is no audio in one direction. Swap front and rear and try again.
One possibility is that the CB is out of tune enough that it is interfering with the Bluetooth. Longshot, but possible. The intercom test will help narrow that down. Intermittent faults are always fun.

[erkmann]

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