CB Modifications
This information is supplied for educational purposes only


Please Remember this information is for educational purposes only and is not an endorsement of the information supplied.
I assume no liability or responsibility with respect to the use of such information.



Expanding the MB8719

Models include:- Uniden Grant/Madison, Cobra 148/2000 GTL etc.

Note: Some newer Uniden's now have the RCI8719 'clone' Pll. You will have to replace the PLL with the old MB8719 BEFORE attempting these mods.

To get coverage from 27.455 - 28.045, find the MB8719 PLL, then locate pins 10,11and 12. Cut the track going to these pins. Locate a ground (chassis or track) .Using a DPDT Center off switch, connect the switch to pins 10,11,12(IC side of the cut) on the MB8719 PLL.This Mod will give you the normal 'FCC' channels in the center position. In the Down position 27.605 - 28.045, In the up position 27.455 - 27.605( on channels 2 -14).See diagram below.

Further expansion can be done by replacing the loop mixer crystal, giving you a new set of 40 channels per crystal

Expanding the Cobra 148GTL-DX/Superstar 360FM(PB010)

Clip off the YELLOW, WHITE, & PINK wires from the ch.9 panel switch. Reconnect WHITE & PINK together for normal LED channel display. Cut off the GRAY wire from the HI/LO TONE panel switch. Remove the grounding jumper at pin 9 of the MC145106 PLL chip. Connect a small bare wire between the center terminals of the now free poles of the CH.9 & TONE switches. Add the two 1N914 diodes and additional switch wiring as shown below

The extra frequencies will now appear in the Ch.12-40 positions of the CHANNEL SELECTOR with the BAND selector in the HIGH position. (The first 11 channels are repeats of existing channels.)The "ch9" position activates the expansion. In the LO TONE position you will get 28.195 Mhz (ch.12) to 28.495(ch.40).if you pull IC7 pins 4 & 2 HIGH at the same time you will get coverage up to 28.705 Mhz. This would need a three position switch.

Emperor 5010

  1. Remove the four screws holding the bottom cover in place.
  2. Lift the bottom cover enough to clear the case and slide it to the side while being careful not to detach the speaker wires.
  3. You should now see the PLL/CPU board at the front of the radio.
  4. With the front of the radio facing you, locate R539 and R540 at the lower right corner of the large chip(HD614081), R539/R540 are side by side and very small.
  5. Remove R539 and R540. You now will get 26.500Mhz to 27.999Mhz plus the 'FCC' band in nine bands.



Galaxy 99

  1. Remove the case and find the small circuit board (EOT004410Z) connected to the left side of the radio as viewed from the component side of the main chassis.
  2. Find the wire that is connected to this circuit board(in step 1)..Remove this wire.
  3. Remove the small screw that holds the small board on to the chassis.
  4. Under this board you will find a 7 pin plug that is not connected to anything. Insert this plug into the empty socket on the small circuit board.
  5. Replace screw back into the small board and close case.


 

MC145106 PLL

This PLL includes the following models...Browning Mark 4A, Dak Mark V, Robyn 440, Dak Mark IX, Lake 600, Palomar SSB500 (late), Regency CB501, SBE 54CB, Keycomm 1000

Also these UNIDEN 'clones' use this chip...Connex 3300, Excalibur base, Excalibur Samurai, Galaxy 2100, Galaxy II, Galaxy Pluto, Galaxy Saturn, President Franklin, Superstar 3600, Superstar 3900, Super Galaxy, Texas Star.

This PLL is getting used in a lot of newer radio's. It often has a pair of MC14008 binary adders to extend the amount of channels available.The PLL uses 9 bit binary programming with internal pull-down resistors.

Modifications are possible by changing the programming of pins 17(P0) to pin 9(P8) or changing the mixing crystal


PLL02A

The PLL02A is the worlds most popular chip used in all the Cybernet chassis. It is simple to modify by changing the binary programming or changing the loop mixing crystal. The US versions use 10 Mhz crystal, Export use 10 or 20 Mhz crystals depending on the model.

The formula for working out the new crystal is :- New Xtal=Current 10 Mhz Xtal ± (N* 0.1125) or New Xtal=Current 20 Mhz Xtal + or -(N*0.225), where N is the number of 40 channel segments above or below the 'legal' 40 channels.

So a crystal of (10.0525 Mhz + 0.1125 Mhz) or 10.165 Mhz would give you 40 channels starting at 27.415 Mhz etc.

Binary Programming the 02A

PLL02A Pinout

  1. Isolate (cut all leads to) Pins 9 & 10
  2. Reconnect the cuts using 3k3 resistors.
  3. (Mount the switches) Most 40ch 02A units have at least 2 two-position switches, ie., ANL on/off and NB on/off. Even the PA switch (if you don't use that feature) can be used. I find it best to solder the NB and ANL always on (completing both circuits). At worst it makes for a quiet-running radio-at best, you won't kick yourself for losing the features entirely!
  4. Firstly, switch #1


This should give you normal 1-40 range with the switch in the UP position(26.965-27405) and upper channels in the DOWN position(27.425-27.705) on channels 12 to 38. You may have to adjust the VFO and broadband the radio, but wait until you have all the extras installed.
Switch #2

Switch #2

Now, in conjunction with switch #1, you have the following "bands";

  1. Switch #1 UP, Switch #2 UP =(26.965-27.405)
  2. Switch #1 DOWN, Switch #2 UP =(27.425-27.705)*
  3. Switch #1Up, Switch #2 DOWN =(26.755-26.065)*
  4. Switch #1 DOWN, Switch #2 DOWN =(26.455-26.745)*+
*- These bands use Channels 12-38 on normal readout or dial.
+- Whaen tuning the VFO, most chassis spread roughly 100-110 channels, so either you lose some low-band or some hi-band operation. the best idea (for most) is to tune until you barely encompass ch"70", thereby giving as much spread as possible to the lower channels. Different radios vary on VFO spreads.
Thanks to Michael Emero the diagrams and text for this mod.

Ranger RCI 2950

The only difference between the old and new versions of the RCI2950 is the new CPU board. They require slightly different modifications.

Old Version

The old version of this radio can be expanded from 26 Mhz to 32 Mhz. Although the use of the 30 -32 Mhz range may need realignment.

First find the PC board with the jumpers on (behind the front panel).Then find 'J2',there is a jumper on pins P3 and P4.If this is jumper is removed you will get coverage from 26 Mhz to 29.7 Mhz.

If this jumper is then place on P1 and P2 coverage will be from 26 Mhz to 32 Mhz(re tuning may be needed to operate in 30-32 Mhz range).

The CPU now needs to be reset by pressing the button located below 'J2'

New Version

As the CPU board has changed the modification is different. On the CPU board there is only one jumper with two positions available. In one position it covers 28 Mhz to 30 Mhz, In the other it covers 26 Mhz to 30 Mhz. But if you jump all three pins together you'll get 26 Mhz to 30 Mhz.(If this is incorrect PLEASE tell me)

 

Uniden HR2510

This radio can be expanded to cover 26-30 Mhz without the need to realign!

Find IC315(UC1201A,UC1170,UC1250a etc) on the synthesizer board PB121BB.Then locate pins 34 and 35 on that chip, these pins are grounded on the HR2510. But on the European models like the President Lincon they are tied high(+5 Vdc).

Therefore to get the extended coverage needed these pins should be tied high.This can be done in the following way.

On the solder side of the synth board pins 34 & 35 are grounded by the same trace. With a razor blade cut this ground trace.

Now find resistor pack RR301.The left pin of this pack is unused and goes to a solder pad. Now connect a small jumper wire between this solder pad and pins 34 & 35 on IC315.

Now you should get coverage from 26.000 Mhz to 29.990 Mhz in the following banks.

Band A: 28.000 to 28.490 Mhz
Band B: 28.500 to 28.900 Mhz
Band C: 29.000 to 29.490 Mhz
Band D: 29.500 to 29.990 Mhz
Band E: 26.000 to 26.490 Mhz
Band F: 26.500 to 26.490 Mhz
Band G: 26.965 to 27.405 Mhz
Band H: 27.000 to 27.490 Mhz
Band I: 27.500 to 27.990 Mhz


Cherokee AH-100

To expand this radio to 400 channels, do the following..

  1. Remove the back cover.
  2. Find the small circuit board that has the PTT and UP/DOWN switches.
  3. On the reverse side of this PCB look for 3 solder islands that end on the outside edge of the board.
  4. Solder a bridge across all three islands.
  5. Re-assemble radio.
  6. Then do the following...

If the radio has been used before you will need to remove the battery and with the power switch ON short out the supply terminals for about a day. This will cause the processor to clear it's self.

Make sure the power switch is on hold down the CH9 button and slide the battery pack back on. Now you should be able to hear the receiver but no display, release the CH9 button and the display should reappear.

Now using the CH9 button you should be able to select 10 bands of 40 channels (A thru J). Now whenever you power up the radio with the CH9 button held down you'll get 400 channels..If you do not hold the CH9 button down you will get the standard 40 channels.

Midland 79-290

To set radio foe 240 channel mode press and hold "DW" and "9" then turn radio on..Select bands by using the "19" button.

To set radio for 28Mhz to 29.7 Mhz press and hold "LCR" and "eMIC"e then turn radio on. To switch back to 40 channel mode repeat process.

Galaxy DX 2527

Remove the top cover. Just above the PLL you will find a jumper block.

There is only one jumper on this block..Move the jumper from bottom left position to top right position.

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Original Page by: Andrew Pepper

Some of the information contained on this page is © Lou Franklin; CBC international,Tel 1-888-I-FIX-CBs