Robyn an-505d needs new mic

[200eazy]

Picked up a Robyn an-505d today. Great radio but the stock mix is lacking a little. I'm wanting to wire either a rk56 or a asatic mic to it. The problem is it has the clarifier in the mic itself. Does anyone know the wiring for this radio, and can it be modded for another mic to work on it.

 

[secret squirrel]

I do not know the Robyn wiring pattern, but you are following a logic line of thought. Whenever I get an older CB with 4 Pin mic, I get it rewired for a Cobra pin out. Keep your good mic wired for Cobra pin out.

 

[Shadetree Mechanic]

With a clarifier in the mic it sounds a bit unusual. Might be better off modifying the existing mic to help it sound better. Maybe try one of these:

https://www.adafruit.com/product/1713

 

[nomadradio]

The later version had a front-panel clarifier with a push-pull switch on it. Pull out to move the clarifier to the mike.

Sounds like you have the early version with the clarifier in the mike only.

You'll need a 20k linear-taper control, a 22k and a 3.3k 1/4-Watt fixed resistor.

And a good place to mount the new control in the radio.

Remove D36. It's near the PLL along the front edge of the main pc board.

Attach one end of the 3.3k resistor to the counterclockwise (CCW) lug of the new 20k clarifier control. The other end of the 3.3k resistor gets a wire to ground, preferably near the PLL chip.

The 22k resistor goes from the clockwise (CW), full-right lug to the center lug of the new control. Don't solder it yet.

Solder a wire from the clockwise (full right) lug of the new clarifier control leading to pin 1 of IC5, the MB3756 chip. Pin 1 is at the end of the chip facing the rear of the radio.

Find D35, located right next to D36. Find the wire that's soldered to the foil pad on the UNbanded endof D36. This wire leads to the mike jack. Pull this wire from that hole. Insert the wire from the new clarifier's center lug here.

Should do it.

Unless I forgot something.....

73

 

[200eazy]

Thanks guys for the help.
I will start gathering the parys for the conversion.
One more question, this radio will likely never be used on ssb. Can an adapter be made that only controls the tx and rx funcrions and not worry about the clarifier?

 

[nomadradio]

Yeah, but it would be more complex than simply wiring three wires up to the three lugs on a control.

Besides, the radio still needs to be on frequency to run AM.

73

 

[200eazy]

Ok thanks for the info.

 

[200eazy]

I wonder what the value of the push pull control for the dimmer is. That would be a good place for the clarifier

 

[200eazy]

Going off the information mentioned above. Why cant you just remove the clarifier circuit from the mic and add it to the new 20k knob? The circuit is already built and ran through the jack into the mic. The main purpose of this mod is to change it to a 4 pin mic jack with cobra pinning.

 

[nomadradio]

Sure, taking the three wires loose from the mike jack that control the clarifier would permit you to attach a new 20k pot to those three wires.

Would still be a receive-only clarifier.

73

 

[200eazy]

Thanks Nomad.

73