rci 2950 (older model) clarifier mod

[TonyV225]

the board number is EPT250137 whats the best clarifier mod for this???.....Thanks Tony

 

[Carl]

dont touch it, you easy adjust the frequency without it.

 

[TonyV225]

Carl I agree with you but its being asked for another guy that insists on doing it he did it and its now working right he says as you turnthere clarifier to the far left opr counter clockwise the frequency goes wild in changing and theres a pulse noise so thats why I am asking what the bet meathod is and if the old and new models can use the same ,mod meathod

 

[Carl]

Frequency Modification

Old Version
Locate the main PCB with Jumpers on it. It is located behind the display board. Find jumper J2. If you remove this jumper, you'll have 26.000-29.700Mhz. If you place the jumper on Pins P1 and P2, you will have 26.000-32.000Mhz. After you "Jump" your radio, you'll need to press the CPU reset button located below J2.

New Version


Real easy to modify! There are a set of Jumpers on the back side of the display board marked "J1" and "J2". One set has a jumper already on it. Remove it and put it on the 2 pins next to it and you'll have 26-29.7mhz. If you jump both set of pins, you'll have 26-32mhz. That's it!

Variable Adjustments


VR1- AM "S" Meter VR12- Sideband High Power (ALC)
VR2- Sideband "S" Meter VR13- AM high Power
VR3- Sideband Squelch VR14- Modulation
VR4- AM Squelch VR15- AM Low Power
VR7- Carrier Balance VR16- Sideband Low Power (ALC)
VR8- RF Power Meter VR21- FM Deviation
VR11- Driver Bias

Unlocking the Clarifier

When you modify the clarifier it will not track on the display (it will give you about 1.5 Khz shift either way) but you will find it useful in CB mode because the frequency cannot be adjusted. It is also useful when using the rig mobile. You don't have to keep pushing the SHIFT key. First, locate the wire harness that runs from the clarifier pot to the circuit board. Just in front of where it plugs into theboard, you will see R-197 (this resistor usually has wax on it). Clip the top of the resistor. Now get a 6" piece of wire and solder it to the stub of wire sticking out of the board (not to the top of the resistor itself). Connect the other end of the wire to pin 3 of IC6. Pin 3 is the leg closest to the front of the radio. Next, locate D-59, just to the left of the clarifier harness. It is a 1N4148 diode. Cut the wire part of this diode to disable it.

Mod for faster scan speed

First take the radios top and bottom covers off. Then remove all the dials off the front face plate. Then take out the screws that hold the front face plate. Now you're looking at the LCD and button printed circuit board. Remove the LCD printed board. Now you should see the main processer board. Lay the radio so that you can see the component. Now look at the board that has the processer on it. If you look at the back side of the boardwhere the batterygoes you should see a blue rectangle shaped resonater marked 2.00g or 2.000 or 2000 kc that would have a x1 or x2 number on the board near it that is also listed in the service manual as a resonator/crystal. If you change this cyrstal with a 8 mhz crystal, it will make your processor run faster in turn giving you faster up/down on your mike, faster scan speed, faster memory scan, and a shorter roger beep (simular to a HR2510). Do not use anything higher than 8mhz! It will lock up your radio otherwise.




RCI 2950, 2970, & 2990 ALIGNMENT PROCEDURE
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1.0 INTRODUCTION

The following steps are required to re-align the RCI-2950/2970. CAUTION: Alignment should only be attempted by personnel trained in RF product testing and alignment.
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PLL SYNTHESIZER / OSCILLATOR FREQUENCY ALIGNMENT
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1.1 Connect digital voltmeter to jumper J13. Adjust L17 for a reading of 2.2 VDC ±0.1 volts

1.2 Connect digital voltmeter to pin 3 of IC7. Adjust L21 to 1.2 VDC ±0.1

1.3 Connect a frequency counter to L61 and adjust VC1 for a reading of 10.240 MHz ±10Hz

1.4 Connect a 50 ohm dummy load to the antenna connector

1.5 Connect a frequency counter to pin 3 of IC14. Ensure that the clarifier is precisely at the 12 o'clock position. Adjust
VC2 for 10.240 MHz ± 10 Hz. Key the transmitter and adjust VR21 for 10.240 MHz ±10 Hz.

1.6 Connect a frequency counter to the cathode of D45. Put mode selector on AM. Key the transmitter and adjust L27 for
10.6950 MHz ± 10Hz.

1.7 Adjust VR7 fully clockwise. Leave the frequency counter connected to D45. Put the mode selector on USB. Key the transmitter and adjust L29 for 10.6925 MHz ± 10 Hz.

1.8 Put the mode selector in LSB. Key the transmitter and adjust L28 to 10.6975 MHz ± 10Hz. Return VR7 to
approximately the middle of rotation.

1.9 Put the mode selector in AM. Connect X10 probe to pin 13, IC17 Check the frequency counter for 5.930 MHz.

1.10 Set the oscilloscope for 50nS (.05uS) per division on the vertical input. Connect X10 probe to IC17 pin 13 and very
carefully adjust L24 and L25 for the best waveform.