So here's an issue we see over and over. The transistor that serves to control the transmitter's modulation level gets 'clipped'. Or in the case of a surface-mount radio, unsoldered.
This results in transmit audio that sounds like someone imitating a police siren, or playing a kazoo. So fuzzy and overdriven that Jimi Hendrix would want to play his guitar through it.
Not so useful if you'd like anyone to understand what you were saying.
Makes the wattmeter look happier. And that's why this transistor Q43 (TR43) got removed from this RCI2950dx radio. Around here we call that "internet audio", because of all the advice you'll find telling you to remove this part.
The other drawbacks to pulling out Q43 are that the sideband will drive hard enough to blow out final transistors. Unless you turn the mike gain down. Way down. And FM transmit won't work unless you play the mike gain like a violin, until it is turned low enough.
Putting Q43 back in works if you have the 2SC2712 surface-mount transistor on hand. We did, and that's how this got fixed. But if you don't have those on hand, there is another one of these parts in the radio you could hijack, and then install here.
The AMC transistor Q68 senses the modulation percentage from the AM modulator and triggers the audio attenuator transistor that got pulled from the radio in the pic above. Removing Q68 will have the effect of turning the AMC trimpot full-bore, and won't affect sideband or FM.
Removing it without destroying the part is easier said than done. But it is the same type part as the one used at Q43, so this will fix the super-distorted transmit audio in a pinch.
If you have a REALLY light touch.
73
This results in transmit audio that sounds like someone imitating a police siren, or playing a kazoo. So fuzzy and overdriven that Jimi Hendrix would want to play his guitar through it.
Not so useful if you'd like anyone to understand what you were saying.
Makes the wattmeter look happier. And that's why this transistor Q43 (TR43) got removed from this RCI2950dx radio. Around here we call that "internet audio", because of all the advice you'll find telling you to remove this part.
The other drawbacks to pulling out Q43 are that the sideband will drive hard enough to blow out final transistors. Unless you turn the mike gain down. Way down. And FM transmit won't work unless you play the mike gain like a violin, until it is turned low enough.
Putting Q43 back in works if you have the 2SC2712 surface-mount transistor on hand. We did, and that's how this got fixed. But if you don't have those on hand, there is another one of these parts in the radio you could hijack, and then install here.
The AMC transistor Q68 senses the modulation percentage from the AM modulator and triggers the audio attenuator transistor that got pulled from the radio in the pic above. Removing Q68 will have the effect of turning the AMC trimpot full-bore, and won't affect sideband or FM.
Removing it without destroying the part is easier said than done. But it is the same type part as the one used at Q43, so this will fix the super-distorted transmit audio in a pinch.
If you have a REALLY light touch.
73
