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CB Modifications

NOTE: These Mods are for Educational purposes ONLY! Perform these at your own Risk.

Cherokee CM-10

CHANNEL MOD
1. Remove bottom cover.
2. Directly behind the M1 button, locate the two capacitors on the front panel that are not soldered in place.

Now do one of these depending on what the radio is like inside.
3.a. Use a fine tip iron and attach the two .1uf capacitors to the pads.
OR if the caps are already attached do this.
3.b. Bridge both pads looking from the component side of the main board they shoud be bridged verticaly on the front panel they looked like they used to be connected at one time, the factory had cut them to only give the normal 40 channels.That is where the left upper and the left lower pads are bridged together and the right upper to the right lower are also bridged together.
4. Power up the radio and you will now see a band select function above the M2 button. You now have 15 bands of 40 channels. A, B, C, D, E, -A, -B, -C, -D, -E, +A, +B, +C, +D, +E.
I have read elsware that installing the caps (if not present) will give 5 bands of channels, 26.065 - 28.305, due to this fact I am not sure which is correct or if there is more then one version.

ATTENTION CHEROKEE ENTHUSIASTS
The newer models may have epoxy over the mod point and the disc caps are not visible.
If you look directly behind the M2 button on the back of the faceplate(component side of board), there may be a dab of yellow epoxy about the size of a dime.
CAREFULLY remove the epoxy with your "Golden Screwdriver" or something similar.
Be sure not to damage the cicuit.(Remember , the epoxy may not be there.)
You should find 4 solder joints about the size of a pencil tip.
Use a small tipped soldering tool and connect the two left joints together and then do teh same with the two right joints.
There is probably enough solder on these 4 points to complete the mod thanks to the fellas at Cherokee.
When you power up the unit, you will see "BAND" above the M6 button in the secondary function mode.
You will get 15 bands of 40 channels starting at 23.815 MHZ and ending at 30.555MHZ (600 channels!)30 MHZ will read as"0005" and so on up the bands. This is normal for this mod.
After the power and modulation modification, you will get about a 4 watt key with a 9 watt swing(+/-).
If you notice a 50 watt swing in the lower and upper bands, remember that your antenna is tuned for 11 meters
not 7,8,9,10,12,and 13 meters. CHECK YOUR SWR READING!

AM POWER
VR502. It is labeled "502" on the board.
MODULATION
VR103. It is labeled "103" on board.

Cobra Mods
This describes how to add channels to the Cobra 148 GTL (PC-412)
And how to boost up the modulation !
The PCB in this radio is almost identical to the Grant (PC-409) and the Madison (PC-411) and it can be used for comparisons
This set is much the same as the Grant/Madison/Washington, as it uses the MB8719 PLL so adding another 40 channels is easy !
Pull pin 10 of the PLL low to go up 64 channels and start another band.
This can be done by using the channel 9 switch, just remove the wire that goes to the display and ground it, then remove the programming diodes and add a jump wire between pin 10 and old junction of the diodes, it should have a wire that goes to the CH 9 switch at the point of the junction.
Retune if needed
Modulation Boosts
1. DONT Remove TR24!
There are two methods to improve the AMC, you can change R130 (a 1.5KOhm for a 500 Ohm, it may be in a diode location close to TR26)
Or you can add a 1K resistor in series on the the middle leg of TR24, to do this just cut the track for the leg and put the resistor across the cut.
2. Change R126 (10k) to a 4.7K
3. Change R124 (10k) to a 4.7K
4. Re-tune L37 and L38 for maximum AM forward power.


COBRA 148F DX
Extra Channels

1)Disconnect the power cord and microphone.
2)Remove the covers of the radio.
3)Find J2 .It is at the front of the radio almost in center.Move the jumper
4)Remove the frequency counter module from the the radio.
5)Now you will see J29,move the jumper diagnally across from where it is now.
6)Re-install the freq counter and put the radio back together.
This will provide coverage from 24.265 - 29.665 MHz.

This shows the mod to get a 10 Khz jump on a Cobra 142GTL.
This mod can also be used on other radios that use a MB 8719 PLL to get a 10 Khz jump.

You can add a 10khz jump mod to the 142gtl, all you need to do is cut the track that goes to pin 16 on the MB 8719 (PLL), bridge the cut in the track with a 4.7K resistor, then all you need to do is attach a center off type toggle switch directly to pin 16, pin 16 will go to the switches center pin, the top pin can go to pin 18 and the bottom pin will go to pin 9, refer to the diagram below:
Pin 18--------|O|
Pin 16--------|O| <--------center off single pole double throw switch.
Pin 9 --------|O|
When this mod is used the switch stays in the center (off) position for normal use, to activate the mod just flick the switch either up or down depending on which channel you are on at the time (it will either need to go + or - depending on the binary code produced at the time), here are what I believe they should be for the A channels:
A channel--- actual channel ----- switch position (UP/DOWN)
3a 4 DOWN
7a 7 UP
11a 12 DOWN
15a 15 UP
19a 20 DOWN
Flicking the switch in the opposite direction will not have any effect, as the pin you are switching would be in the same state already (Hi/Low), which means for example that if you where on CH 4 and flicked the switch UP instead of DOWN you will still be on CH4 !
It is possible to just use a plain on/off switch and a relay, which will automatically shift the pin voltage high or low depending on the binary code, but it is hard to describe and I have not tested it yet, although it should work in theory, the channel offset would still occur as well (i.e. 3a is ch4, 7a is ch7, you need to be above some and below others).

Galaxy Melaka
Channel Expansion
1) Remove top and bottom covers and open the radio.
2) Find a small jumper wire on the bottom side of the main board towards the front.
3) This wire is soldered to ground as well as 2 pins.
4) Unsolder both ends of the wire.
5) Make sure the 2 pins are no longer shorted together.
Tweak & Peak
Audio Limiter - VR-14
AM Power - VR-13
SSB Power - VR-12

Channel Expansion gALAXY 44v
1) Open the radio.No Really?!?
2) Find the small circuit board on the left of the radio.
3) Cut the green wire and tape it off.
4) There is an unplugged connector by this board..plug it in.
5) Near the front of the radio there is a connector marked +10K. Reconnect the plug to the board.
6)That's it. You now have 8 bands of 40 channels.25.165-28.755.
Tweak & Peak
Audio Limiter - R249
AM Power - VR13

Galaxy 66V
Channel Expansion
1) Open the radio.No Really?!?
2) Find the small circuit board on the left of the radio.
3) Cut the green wire and tape it off.
4) There is an unplugged connector by this board..plug it in.
5) Reconnect the plug to the board.
6)That's it. You now have 8 bands of 40 channels.25.165-28.755.
Tweak & Peak
Audio Limiter - TR53
AM Power - VR13

Galaxy 73V
Channel Expansion
1) Remove the bottom speaker cover.
2) Remove the screw holding the small silver freq. counter module.
3) Locate the loose 8 pin connector and plug it in to J1.
4) Clip the short jumper wire on the rear corner of the microprocessor board.
5) That's it. You now have 8 bands of 40 channels.25.165-28.755.
Dual Watch
1. Locate the cut yellow and gray wires on J2
2. Locate the cut yellow and gray wires in the wiring harness
3. Solder the two yellow wires together and the two gray wires together
4. Tape up the solder splices and replace the speaker cover

Galaxy 88 HL
Channel Expansion
1) Remove the covers on the radio.
2) Find the small long boardon the keft side with the radio upside down.
3) Remove the RED jumper wire on top of that board.
4) Close the radio, plug in the power cord , and turn it on.
5) That's it. You now have 8 bands of 40 channels.25.165-28.755.
Tweak & Peak
Audio Limiter - TR53
AM Power - VR13

Galaxy 99V
Tweak & Peak
Audio Limiter - TR53
AM Power - VR13



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