No cause the directions I went by told me to cut out C10 and the RX Out Cable. What did we talk about on CL? Yeah it is a small world after all, lol. Below is the directions I went by.
RFX75 – Cobra 29 Installation
1. Locate the capacitor at C10 on the RFX75 and carefully cut it off the board.
2. Cut the Yellow and Blue wires off the RFX75 board.
3. Cut the RX OUT coax cable off the RFX75 board. Take care to cut it close enough to the PCB so that it
does not short out on anything.
4. Drill and mount the RFX75 on the back of the radio using the supplied hardware.
5. From the radio, remove C8 (keep part for later use), C53, C57, R56, L12, and the final transistor.
6. Route the RF IN coax through the hole where the final transistor was so that it can easily be soldered to
the solder side of the radio PCB. Solder the coax center conductor to the front hole of R123 and the coax
shield to DC ground.
7. Solder the Red and Black wires to the back of the DC power jack (observe polarity!).
8. Solder the Orange wire to the front side of L15.
9. Solder the RF OUT coax center conductor to the rear hole of L12. Solder the coax shield to the chassis
ground tab on the back of the radio’s antenna connector.
10. Using the 15pF capacitor that was removed from C8, solder one end to JP24 and the other end to the
rear hole of L12 on the solder side of the board. Make sure to insulate the leads. You will probably have
to lengthen the leads of this part to make it fit. This re-connects the RX circuit in the radio.
11. Add a short jumper wire from the ground area at R142 over to the audio transformer’s ground pad. This
eliminates a ground loop that can cause the radio to squeal on transmit.
12. In the radio, replace R48 with a 470K ohm, ¼ watt resistor.
13. In the radio, replace C42 with a 3300μf, 16volt electrolytic capacitor.
14. Retune the transmit and receive of radio for best performance. IMPORTANT: If the carrier is higher
than 15 watts you should take the following steps to reduce the carrier to below 15 watts.
a. After confirming that the radio is functioning properly, remove JP36 and install a 1000μF
electrolytic capacitor in its place with the negative lead in the rear hole and the positive lead in
the front hole.
b. On the solder side of the radio’s circuit board add a 10 ohm - 47 ohm, ¼ watt resistor across the
two points where you installed the 1000μF capacitor. This will allow you to adjust the carrier -
The higher the resistor value, the lower the carrier. Typically, 33 ohms is about right.
