Fitting an External Antenna

I meant to say - Fitting an RF testpoint for evaluation purposes or to clean up the output with an LPF

V_cc of 3.3v is originally present at the antenna pad so you may need to cut a track between the two linked pads just after the PA transistor and bung a cap in there in order to provide DC blocking. If you're planning to use a short length of wire or an antenna with no DC path, you could skip this stage.

There's a cap in between ANT and GND and this needs to be whipped out as we no longer need RF going to the audio lead.

Lastly, the inductor which used to provide an audio ground for the audio lead whist at the same time preventing RF going to ground needs to be removed and linked through. In fact, an RF ground could be just taken from a suitable point but hey, there's a hole there, why not use it?  

To the right of the board, you may just notice that I have moved the cap which originally sat between the two antenna pads to another position just after the output transistor. The track below it naturally needed to be cut.

Also, the inductor has gone and in its place is a blob of solder.

Below shows the job in more detail. 

The two lovely holes which Chaoyu gave us are in fact a multiple of 0.1" apart so if you knock out three pins, a standard header drops straight in.

I used this because I had run out of small PCB pins.

The back of the housing could, in fact, be drilled to accept a socket. This time round, I went for a flying RG174 miniature co-ax soldered to the two pins I had created. This was terminated with a suitable BNC male.

This coax exited out of the port where the audio signal socket usually docks.

CY-668A Technical Description

Connecting to a PA

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