Yeah, that's right. A Cobra one thousand, NOT a two thousand. It's AM only, but looks a lot like its bigger brother.
And yeah, a roger fart. First one of these I have seen. Looks like it was made in the USA, not the other side of the planet.
This thing has no name, no hint of where it comes from anywhere on it. Just "Omega Roger Fart 2019".
The trimpot sets the tone of the single beep. From way too shrill, down to fog-horn. The resistance value marked on it is ten megohms. Yup, 10 megs. Makes it sound as if extending wires to an external control knob might be tricky. Not gonna try that today.
Hijacking the PA/CB switch is easy for this radio. The switch has only two poles. The pole on the outboard side removes power from the final and driver in PA. The inboard side selects between the PA jack and the external speaker jack.
The white and violet wires are unsoldered from the pc board, and soldered together. You can slide shrink over it without a picture, right? This takes care of the speaker circuit.
The orange and red wires get unsoldered from pads leading to the outboard half of the switch. They get soldered together. This is the side of the switch we will repurpose to shut off the roger fart.
The transmit wire gets unsoldered from pin 3 on the mike jack, and soldered to the "Tx" pin of the beep. Pin 4 wire comes off the jack and goes onto the "Rx" pin.
The board's keying wire is usually green. This one is blue, but the board is marked "Gr" where it's attached. The other end gets soldered to pin 3 of the mike socket. The black wire gets soldered onto pin 1. The audio wire in this case is white. It got soldered to the clockwise lug of the mike gain pot. This should keep the beep loud no matter where the mike gain knob is set.
I didn't bother with pictures of the stuff the instruction sheet shows how to do.
The green rectangular capacitor marked ".22" in the first pic is a mod. The original cap was a 0.1 uf. Made the beep about a half second long. Customer said make it longer. Doubling the size of the cap stretches it out to about one whole second.
The design of this board looks just like the Taiwan-made roger beeps that were sold for decades. Never got around to tracing a schematic that I remember. Don't remember needing to. But it's the same in one important way.
The instructions tell you to put a switch in line with the audio wire. This will stop the beep, but now you'll have a "roger silence". The unkey will still be delayed, with or without the beep audio.
I find this a crude approach. Here is a diode that will provide a true "Off" for both the delay and tone. This diode, marked "D8" on this board, gets one lead unsoldered from the board. With this connection broken, the beep AND the delay will both be disabled.
A wire goes to the free end of the diode, and another wire to the pcb foil pad where it was removed.
And here we find ourselves back at the outboard side of the PA switch. Our two diode wires go to the foil pads where the orange and red wire were removed.
Now, just why a customer wants a one second-long roger fart on his radio is not my department.
But making it happen certainly is.
73
And yeah, a roger fart. First one of these I have seen. Looks like it was made in the USA, not the other side of the planet.
This thing has no name, no hint of where it comes from anywhere on it. Just "Omega Roger Fart 2019".
The trimpot sets the tone of the single beep. From way too shrill, down to fog-horn. The resistance value marked on it is ten megohms. Yup, 10 megs. Makes it sound as if extending wires to an external control knob might be tricky. Not gonna try that today.
Hijacking the PA/CB switch is easy for this radio. The switch has only two poles. The pole on the outboard side removes power from the final and driver in PA. The inboard side selects between the PA jack and the external speaker jack.
The white and violet wires are unsoldered from the pc board, and soldered together. You can slide shrink over it without a picture, right? This takes care of the speaker circuit.
The orange and red wires get unsoldered from pads leading to the outboard half of the switch. They get soldered together. This is the side of the switch we will repurpose to shut off the roger fart.
The transmit wire gets unsoldered from pin 3 on the mike jack, and soldered to the "Tx" pin of the beep. Pin 4 wire comes off the jack and goes onto the "Rx" pin.
The board's keying wire is usually green. This one is blue, but the board is marked "Gr" where it's attached. The other end gets soldered to pin 3 of the mike socket. The black wire gets soldered onto pin 1. The audio wire in this case is white. It got soldered to the clockwise lug of the mike gain pot. This should keep the beep loud no matter where the mike gain knob is set.
I didn't bother with pictures of the stuff the instruction sheet shows how to do.
The green rectangular capacitor marked ".22" in the first pic is a mod. The original cap was a 0.1 uf. Made the beep about a half second long. Customer said make it longer. Doubling the size of the cap stretches it out to about one whole second.
The design of this board looks just like the Taiwan-made roger beeps that were sold for decades. Never got around to tracing a schematic that I remember. Don't remember needing to. But it's the same in one important way.
The instructions tell you to put a switch in line with the audio wire. This will stop the beep, but now you'll have a "roger silence". The unkey will still be delayed, with or without the beep audio.
I find this a crude approach. Here is a diode that will provide a true "Off" for both the delay and tone. This diode, marked "D8" on this board, gets one lead unsoldered from the board. With this connection broken, the beep AND the delay will both be disabled.
A wire goes to the free end of the diode, and another wire to the pcb foil pad where it was removed.
And here we find ourselves back at the outboard side of the PA switch. Our two diode wires go to the foil pads where the orange and red wire were removed.
Now, just why a customer wants a one second-long roger fart on his radio is not my department.
But making it happen certainly is.
73
