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Modifications for the Icom IC-970


 

IC-970 with 9600 Baud
Icom IC-970H expanded RF
Icom IC-970H Repeater Operation
AFC Sat Control FOR IC-970H

 

IC-970 UHF band frequency readout shows only dash

PLL control voltage out of range.

Correction: Replace PLL unit LPL trimmer capacitor to ceramic 12pF.

Remove both covers.
When radio is front panel to you, PLL B is right side of radio.

Remove all connectors of PLL unit and two coaxial cables what going to UHF front unit.
Unscrew four screws and pull PLL unit from radio.

Pull PLL-B LPL box upper cover and you see black plastic capacitor right below.
Unsolder solder side shield using quite efficient solder iron and solder sucking wick.

Capacitor is soldered only two legs, unsolder them. On component side, there is bee wax but try pull faulty capacitor out.

Put new ceramic capacitor and to solder it.
Assemble PLL unit back to the radio and connect all removed cables back.

Put operation voltage to the radio and make measurements PLL LPL voltage.
Displayed frequency 430.0500 mode FM. Adjust new capacitor and measure R62 (its position quite below PLL box) voltage about 1V.
Displayed voltage 430.0490 mode FM, measure R62 voltage about 1.2V or so that displayed frequency stay properly.

When all ok and frequency display stay ok, assemble shields and all other parts and make QSO`s.

I no take any liability this operation.

 

 
IC-970 with 9600 Baud
 
     

To use the ICOM IC-970 on the UOSAT's (9600 baud), I made the following modifications:

Transmit
Solder a shielded wire (I used RG174) to the anode of D16 (1SV50E). This is at the junction of R52 (470K) and C44 (.0047). Make sure to solder the shield to the adjacent PC board ground plane.

Receive
Solder a shielded wire to pin 9 of IC11 (MC3357P), again make sure to solder the shield to the PC board ground plane.

Both transmit and receive are on the main unit circuit board. Make sure that you use IC11 as this is the sub band receiver. If you plan to use the IC-970 for terrestrial packet (ie. simplex on either 145 or 440) you will need to add another shielded wire to IC5, which is the main receiver discriminator.
I then brought the shielded wires out the rear of the radio.
I did this by removing the plate which covers the two holes located below ACC(1). In order to disconnect the wires from the modem, I installed two phono jacks in the center of the holes on the metal plate. I have used this setup with the G3RUH modem, PacComm NB96, and the MFJ-9600.
I found that it was not necessary to add the 10K series resistor to the transmit audio/deviation line. On all three, with the center of the 10K pot range as 12 o'clock, I found that about 1 o'clock to work best on for me.

Note:
Make sure that the DC power source for the TNC and 9600 baud modem are on a clean supply (no ripple). Several users have found this to be the reason they could not get their modems to work. Also make sure that the TNC modem switch is set to 9600 baud as this provides the 153.6kHz to the modem. The modem documentation is not very clear in this area. I run the terminal speed at 19,200.

If you have any questions, I can be reached at:

Dale Hagert NM0H
3881 Serpentine Circle
Eagan, MN 55122
612-452-1030
 

 

 
Icom IC-970H expanded RF
 
     
Author: CT1EMJ - Joćo Laginha

 
  1. Remove power and antenna.
     
  2. Remove top and bottom covers.
     
  3. Locate and expose the logic board. (see drawing)
     
  4. Locate and cut resistor R187.
     
  5. Locate and cut resistor R190.
     
  6. Locate and cut resistor R219.
     
  7. Locate and cut resistor R191. (X Band Repeater Mod)
     
  8. Locate resistor position R1887 and add a 10K Ohm resistor.
     
  9. Reassemble the radio.
     
  10. Reset the microprocessor. (Push and hold [ MW ] and power on.


 

 

 

 

 
Icom IC-970H Repeater Operation
 
     
Author: CT1EMJ - Joćo Laginha


 
  1. Set the MAIN and SUB Frequencies.

     
  2. Turn the Radio Off.

     
  3. Press [ LOCK ] switch ON.

     
  4. Press and hold [ FUNCTION ] & [ M/S ] switch and turn on.

     
  5. To cancel Repeater Function - Turn the [ LOK ] switch off.


 

 

 
AFC Sat Control FOR IC-970H
 
     
Author: CT1EMJ - Joćo Laginha


 

Material

  • IC - LM 339 x 1
  • Resistence 22k x 1
  • Resistence 2,2k x 2
  • Green Led x 1
  • Red Led x 1
  • Pot 5k x 2

                                 

This Logic board is design and tested for Icom IC-970H and Yaesu FT-736R, however other radios can be used with it.

I have decided to install mine inside of the radio.

To use it with Yaesu FT-736R use the following connections:

Microphone Pins 

 
Pin 2 = +5 Volts
Pin 1 = UP Key
Pin 7 = GND - Ground
Pin 2 = DOWN Key

Don't forget to adjust 5K Pots to center Sat Frequency.