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HR2510 RIT / Clarifier Mods
The RIT (Receiver Incremental Tuning) on the HR2510 is a Clarifier control to help ‘tune in’ usually SSB signals that may be transmitted off of center. The RIT only works on the receiver. The HR2510 does not allow ‘slide’ on transmit unless its modified. Many people wish to ‘Open’ the RIT (or Clarifier).
Everyone has a different mod for this one, I will list the ones I know. Basically they are about the same, You need to disconnect the existing voltage from the clarifier (RIT) circuit and add a constant voltage to the clarifier (RIT) control circuit. This voltage needs to be there during transmit.
RIT MOD I
Find D150 on the main circuit board. With the radio right side up, it will be found in the front right-hand corner of the PCB. Lift or clip one end of this diode.
Find the orange wire comming from the RIT/RF GAIN PCB (PB-120). From there it goes to the main PCB to a 4 wire connector (Yellow/Orange/Red/Brown) located on the left side of the main PCB near the center of the radio. Clip the orange wire from the connector and feed it through to the other side of the radio. Solder it to pin 3 of IC 311. This will be a three-pin voltage regulator located just to the right of the large microprocessor (IC315). The pins on IC 311 are numbered from left to right.
To center the RIT:
Locate the 3 tuning coils on the front left corner of the main PCB. The exreme left coil labeled L116, adjusts USB. The center coil is labeled L118, adjusts LSB. The right coil labeled L117, adjusts CW. There will be some interaction between the coil adjustments so you may need to repeat retuning a few times. I suggest you start with the USB coil and end with the CW coil. The Mod will give you plus or minus 3 Khz slide, the RIT will NOT change the display, but the transmit and receive frequency will track together now.
RIT MOD II
Cut D150 on the main PCB. Locate the orange wire at the top of the RIT PCB, cut and connect to pin 3 of IC107. This is a 3 pin transistor bolted to the left side of the case next to VR116. Pin 3 is the lead closest to the back of the radio. You now have +/- 5khz slide.
RIT MOD III
Find the orange wire comming from the RIT/RF GAIN PCB (PB-120). From there it goes to the main PCB to a 4 wire connector (Yellow/Orange/Red/Brown) located on the left side of the main PCB near the center of the radio. Clip the orange wire from the connector. Find the red wire (8 Volts) on the mode switch PCB and solder the orange wire to it.
Set the RIT to center (12 o’clock) Mode switch to AM Frequency to 28.000 Mhz.
Connect a Frequency counter to TP306. Adjust L315 for 6.200Mhz
Connect a Frequency counter to TP304. Adjust L318 for 38.695Mhz
Connect a frequency counter to TP1.
Set the Mode switch to USB, adjust L116 for 10.6975Mhz.
Set the Mode switch to LSB, adjust L118 for 10.6925Mhz
Set the Mode switch to CW, adjust L117 for 10.6950Mhz
Check RIT range. It should be +/- 4Khz
RIT MOD IV
Find the orange wire comming from the RIT/RF GAIN PCB (PB-120). From there it goes to the main PCB to a 4 wire connector (Yellow/Orange/Red/Brown) located on the left side of the main PCB near the center of the radio. Clip the orange wire from the connector. Solder the orange wire to Jumper 13 (JP13) +8V constant . Cut D150.
To center the RIT: With the Mode switch to AM, Frequency at 28.000Mhz, RIT at 12 o’clock, connect a frequency counter to TP304, adjust L318 for 38.695Mhz.
D150 is for the HR2510, D43 is for the HR2600, also in the HR2600 the wire should be orange. The connector on the main PCB is a 5 wire connector. The orange wire will be the third wire in the connector from the back.(Corrected 8/2004)
More information to be added soon so come back often.
If you have any Questions or Comments, you can E-Mail me at Rogerbird