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Super-Talk/Swing Kit.

Here you go: 1- 100uF 35v electrolytic capacitor, 1- transistor TIP-31C

Other transistors you can use and their crosses:
TIP3055 = ECG 392 = 276-2020(Radio Shack)
TIP31C = ECG 291 = 276-2020 (Radio Shack)
TIP120 = ECG 261 = 276-2068 (Radio Shack)
 

DON'T BOTHER buying the "SUPER-TALK" kits. Make your own!! +
 

 
 Here are all the VR's for the DX88HL:

 1.VR 1...AM/FM S-Meter
 2.VR 2...SSB S-Meter
 3.VR 3...SSB Squelch Range
 4.VR 4...AM/FM Squelch Range
 5.VR 5...FM Deviation
 6.VR 7...SSB Carrier Balance
 7.VR 8...RF Meter
 8.VR10...Final Bias
 9.VR11...Driver Bias
10.VR12...SSB ALC
11.VR13...AM/FM High Power
12.VR14...AM Modulation
13.VR16...AM/FM Low Power
14.VR20...Final Bias
15.VR21...TX Offset
 

Channel Expansion

 

1) Open up your radio.
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 55V

Tweak & Peak

 

Audio Limiter - TR53
AM Power - VR13

Galaxy 66V

Channel Expansion

 

1) Open up your radio.
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, Channels 25.165-28.755.

Tweak & Peak

 

Audio Limiter - TR53
AM Power - VR13

Galaxy 99V

Tweak & Peak

 

Audio Limiter - TR53
AM Power - VR13

 
Wondering about the "UNCLE MOD

SUPERSTAR 1700, 3600, 3900

MODULATION: VR14 or cut R249
AM POWER: VR13
SSB POWER: VR12

POWER TWEAK:
1. Remove TR32
2. Replace R174 (10k) with a 1 K
3. Replace R187 (10k) with a 1 K

CLARIFIER:
1. Find the GREEN WIRE located at point 54 and UNSOLDER it.
2. Resolder this GREEN WIRE to POINT 14 (8.7 V) or to TR 41 collector.
3. Find the YELLOW WIRE on the clarifier control and UNSOLDER it. Insulate the cut end. This wire is no longer used.
4. Find D75 (located near POINT 53 and VR15) and lift one end.
5. Find R135 (33k) and lift one end.
6. Double check all work for shorts.

NO EXPLOSION? Then you should be able to track on TX and RX!

CHANNELS:
1. Locate pins #12 and #13 on IC7 (MC14008BCP chip).
2. Using a SPST toggle switch, wire as follows:
Center of toggle switch goes to pin #13
The other goes to pin #12

Your channels should work with your band selector on "D" band.

(These 2 radios are the same except for the name)

VR1 - AM/FM S METER ADJUST
VR2 - SSB/CW S METER ADJUST
VR3 - SSB SQUELCH RANGE
VR4 - AM SQUELCH RANGE
VR5 - FM DEVIATION ADJUST
VR7 - CARRIER BALANCE ADJUST
VR8 - RF METER ADJUST
VR10 - FINAL BIAS ADJUST
VR11 - DRIVER BIAS ADJUST
VR12 - ALC ADJUST
VR13 - AM POWER ADJUST
VR14 - AMC
VR16 - CW MON ADJUST
VR21 - Tx FREQUENCY ADJUST
TR32 - IS THE AMC LIMITER

"I don't recommend removing TR32 as it disables VR12 ALC, SSB power will be at full blast.
Instead clip or remove R249. This only disables AMC not ALC.
Tune L40, L43, L44, and L33 for maximum forward swing on wattmeter.
Adjust AM power for no more than 5 watts dead-key - if running a linear amp set at 3 watts dead-key.
Adjust ALC for no more than 20 - 25 watts PEP on SSB.
For Talkback remove D80."

+ 10 KHz Jump Switch

 

1)Get a SPST switch and mount it in the radio.
2)Find IC 6 & 7 by the PLL chip. You will see J68 and J 69
3)Solder a wire from one side of the switch to J68.
4)Solder a wire from the other side of the switch to J69.
5)That's it .Flip the switch to jump up one channel.

Open Clarifier

 

1)Find D75 and R135 and cut one end of them.
2)On the back of the clarifier knob follow the green wire to the PC board. Cut this wire from the PC board.
3)Now Solder this wire to a constant 8VDC source, like the collector of TR41.
4)Take the yellow wire and cut it from the knob. Tape this wire it is not needed.
4)This should make the radio TX/RX on the same frequency.

10 Meter Mod

 

1)Find IC7 ny the PLL chip.
2)Get a SPST switch and mount it in the radio.
3)Solder a wire from one side of the switch to Pin #13.
4)Solder a wire from the other side of the switch to Pin #12.
5)That's it .Put the radio on 'Band D' then flip the switch to jump up to 28.300 to 28.500.

Tweak and peak

Audio Limiter - Cut R249
AM Power - VR13
SSB Power - VR12

Cobra Mods   Radio                Modulation               Power

7 PLUS	VR4 or CUT D8	L11,  L12,  L13
10 PLUS	VR4 or CUT D8	L11,  L12,  L13
18 LTD	CUT D13 or CUT R84	L7,  L6,  L5
18 PLUS	CUT D12	L 7
18 RV	RV501 or CUT D502	L304,  L305,  L306
19	CUT D11	L5,  L8,  L9
19 GTL	VR6 or CUT D9	L15,  L16,  L17
19 LTD	VR6 or CUT D9	L15,  L16,  L17
19 LTD CLASSIC	VR4 or CUT D7	L7,  L8
19 M	REMOVE C73	L8,  L5,  L3
19 PLUS	RV501 or CUT C511	L305,  L306
19 PLUS (Plastic Case)	RV4 or CUT D8	L11,  L12,  L13
19 XS	CUT D105
20 B&K	CUT CD20 & CD21	T11,  T10,  C60
20 LTD	CUT D13
20 PLUS	RV501 or CUT C511	L305,  L306
20 PLUS (Plastic Case)	RV4 or CUT D8	L11,  L12,  L13
21	REMOVE C105 & C106	T11,  T10,  C60
21A (Old)	CUT D24	L9,  L8
21 GTL	VR5 or CUT D9	L13,  L10,  L9,  L8
21 LTD	VR5 or CUT D9	L13,  L10,  L9,  L8
21 LTD CLASSIC	VR4 or CUT D7	L7,  L8
21 PLUS	CUT 1.5K res. next to TR34	L12,  L10
21 X	VR207 or CUT D212	L212,  L214
21 XLR	RT4 or CUT D13	L15,  L12,  L11
23 PLUS	RV501 or CUT D502	L304,  L306,  L307
25 GTL	VR5 or CUT D9	L13,  L10,  L9,  L8
25 LTD	VR5 or CUT D9	L13,  L10,  L9,  L8
25 LTD CLASSIC	VR5 or CUT D9	L10,  L9,  L8
25 PLUS	CUT 1.5K res. next to TR34	L12,  L10
26	CUT D24	L7,  L8
28 A	CUT CD28 & CD29	T12,  L2,  L5
29 A (OLD)	CUT D24	L7,  L8
29XLR	VR5 or CUT D14	L15,  L12,  L11
29 GTL	VR4 or CUT D11	L14,  L13,  L12
29 LTD	VR4 or CUT D11	L14,  L13,  L12
29 LTD CLASSIC	VR4 or CUT D11	L14,  L13,  L12
29 LTD GOLD	VR4 or CUT D11	L14,  L13,  L12
29 PLUS	CUT D20	L12
31 PLUS	CUT D19	L13,  L12,  L11
32 XLR	CUT CD11 & CD12	L5,  L3
33 PLUS	VR4 or CUT D17	L11,  L9
39 LTD (S.O.S.)	RV1
40 PLUS	RV104 or CUT D203	L305,  L306
40 X	RV201 or CUT D203 or C215	L304,  L305,  L306
41 PLUS	VR4 or CUT D21	L19,  L20,  L21
45 XLR	VR105 or CUT D119	L113,  L109
46 XLR	VR105 or CUT D119	L113,  L109
47 XLR	VR105 or CUT D119	L113,  L109
50 XLR	VR5 or CUT D119	L109

 

55 XLR	VR5 or CUT D119	L109
62 XLR	VR3 or REMOVE C67	L16,  L15,  L12
63 GTL	VR3 or CUT D11	L11,  L10,  L9
66 GTL	VR2 or CUT D4	L14,  L15,  L17
66 LTD	CUT  R54
67 LTD	RV4 or CUT D212	L306,  L307,  L308
77 X	VR207 or CUT D212	L211,  L212,  L214
78 X	VR6 or CUT D9	L11,  L12,  L15
85	REMOVE Q17	L3,  T4
86 XLR	CUT CD9	L3
CAM 89	ADD 1K res. in series with C110	L13,  L12,  L9
87 GTL	VR6 or CUT D16	L17,  L16,  L13
89 GTL	VR6 or CUT D16	L17,  L16,  L13
89 XLR	VR5 or CUT D14	L15,  L12,  L11
90 LTD	VR201 or CUT D203
132 (OLD)	CUT Q25	T14,  T15,  L3,  C116,  (ssb) R136
132 A	CUT CD39 & CD40	R79 (ssb) R87
132 XLR	R134 or CUT R125	L3,  (ssb)R130
134	CUT D40 & D41	L8,  L10 (ssb)VR15
135 (OLD)	CUT Q25	T14,  T15,  L3,  C116  (ssb)R136
135 XLR	R134  or CUT R125	L3,  (ssb)R130
138 A (OLD)	CUT D40 & D41	L8,  L10  (ssb) VR15
138 XLR	VR7  or  VR6	VR8,  (ssb)CT7
139	VR12  or CUT D63	L12,  L10,  (ssb)VR15
139 XLR	VR7 & VR6	VR8,  (ssb)CT7
140 GTL	CUT R104	VR6,  (ssb)VR7
142 GTL	CUT R104	VR6,  (ssb)VR7
146 GTL	VR5  or CUT TR29	VR10,  (ssb)VR6
148 GTL	CUT R131	VR10,  (ssb)VR11
148 GTL-DX (early prod. model)	VR5	VR11,  (ssb)VR7
148 GTL-DX (late prod. model)	REMOVE VR14 or CUT TR32	VR13,  (ssb)VR12
148 GTL-B	VR14	RV15,  (ssb)RV13
148 GTL-DX (copy ver.)	RV12	RV11,  (ssb)RV6,RV3
1000 GTL	VR6  or CUT D16	L17,  L16,  L13,  (ssb)
2000 GTL	CUT R131	VR10,  (ssb)VR11
GTL 150	RV14	RV13,  (ssb)RV12,RV4

 

Cobra 25 GTL/LTD/CLASSIC

MODULATOR
PARTS NEEDED: 1- 220uF (16 to 25 volt) electrolytic capacitor.
1- 100 to 200 Ohm resistor. (1/4 to 1/2 watt)

ASSEMBLY:
1. Make sure your radio is peaked out.
2. Unsolder JP6 near final.
3. In JP6 holes, solder the 220uF capacitor. (negative side of cap. faces final)
4. On the solder side of the board, solder the resistor across the 220uF capacitor.
You can use different resistor values to get the desired dead-key.

VARIABLE POWER:
1. Find the two wires that are attached to the RF gain control, follow them to the PC board and UNSOLDER them.
2. Solder in a jumper wire from where you removed the wires on the board. This will restore receive.
3. Place the two wires from the RF gain control in your mod kit by soldering one wire to each of the 220uF capacitors leads.

REPAIR TIPS:
25 GTL:
1. Channel display reads all 7's or 8's: Leaky/shorted C104(470uF 10v). Replace with a 16v or 25v.
2. NO TX: Check for shorted 33uF(10v) capacitor across C87.
3. OVERMOD: Check D19,TR14,VR5
25 LTD
1. OVERMOD: Check D9
2. LED goes out and NO TX when keyed up: Check C118
25 LTD Classic:
1. Burned R89(15 Ohm 1/2 watt): Replace with a 1 watt.
2. OVERMOD: Check for missing or cut D9, missaligned VR5.

Cobra 29 GTL/LTD/CLASSIC

POWER TWEAK #2
1. Remove final and replace with a 2SC1969 transistor.
2. Remove R123 and replace with a jumper.
3. Replace C58 with a 180pF capacitor.
4. Re-tune coils.
CAUTION!!! I do not know if both of these power mods can be done at the same time!!!

SAMS PHOTOS: 217
AM LIMITER: D-11
MODULATOR AND VARIABLE POWER
ASSEMBLY:
The instructions are the same as the Cobra 25 above,EXCEPT the following:
1. Unsolder JP36 instead of JP6.

REPAIR TIPS:
29 GTL:
1. "Motorboating": Locate C242(.001)on pin 5 of TA7222 audio ic and move to pin 4 of ic.
2. Weak mic gain: Some raios have a 2SC372 mic amp. Replace with a 2SC945.
3. Receive on adjacent channel: Bad solder joint to C131 (next to 10.240 crystal).
29 LTD:
1. OVERMOD: Check D11
2. PLL dead, no TX or RX: Shorted C112
3. No TX/RX with Channel LED lit on RX and then goes out when keyed: Bad /shorted C119.
29 LTD Classic:
1. OVERMOD: Check D11. Missaligned VR4.
2. Internittent audio/modulation: Bad solder joints on pins 1&2 or 2&3 of audio ic.
3. TUNE UP TIPS: L11 is the TVI trap. DO NOT adjust!!! Stretching L12 gets moe output. L14 peak is about a turn or two up from factory original setting.

Cobra 148 GTL

SAMS PHOTOS: 249
MODULATION: Cut R131
AM POWER: VR10
SSB POWER: VR11

CHANNEL TWEAKS:
I have found that the easiest way to do this without hacking your radio with a lot of switches is to install the EXPO 100 kit "L" expander kit.
This is an excellent kit and installs quickly with very little tools. This way you don't have to fumble around trying to remember which switch goes where, etc...
 

CLARIFIER:
1. Cut one side of R44 and D52. Remove R174 and solder a jumper wire in its place.
2. Follow the RED WIRE from the clarifier control to where it connects to the PC board and cut it loose.
3. Solder this RED WIRE to the circuit board ground.
NOTE: Some radios have a YELLOW WIRE instead of the RED WIRE.
4. Follow the ORANGE WIRE from the clarifier control to where it connects to the PC board and UNSOLDER it.
5. Resolder this ORANGE WIRE to pin 3 of the MB3756 regulator.
With any luck, you should slide about 5Kz down and 1Kz up.

GRANT-XL (8719 PLL)

POWER TWEAKS:
1. Remove TR24
2. Replace R126 (10k) with a 2.2k.
3. Replace R124 (10k) with a 4.7k
4. Re-tune coils L37 and L38 for maximum forward swing on AM mode.

MODULATION: Remove R131
AM POWER: VR10
SSB POWER: VR11

CLARIFIER:
1. Find D52, R44 and R174 and remove them.
2. Solder a jumper from where you removed R174
3. Follow the WHITE WIRE from the clarifier control to where it attatches to the PC board and UNSOLDER it.
4. Resolder this WHITE WIRE to the PC board ground.
5. Follow the ORANGE WIRE from the clarifier control to where it attatches to the PC board and UNSOLDER it.
6. Resolder this ORANGE WIRE to pin 3 of MB3756 Regulator.

NOTE: Some radios have different colored wires on the clarifier control. They are:
YELLOW instead of ORANGE
RED instead of BLUE

If all goes well, you should slide about 4 down and 1 up.

WANT MORE SLIDE??
1. Remove D51 and put in a jumper.
2. Install a "super-diode" in place of the stock varactor D35.
3. Add a 4.7uh to 10uh choke to the banded-end of the stock varactor.

10 KC JUMP:
Basically, you need to either add voltage or ground pin #16 on the MB8719 PLL.
Here's how to do a 10 Kc UP jump only:
1. Cut trace to pin #16 on the PLL.
2. Install a 4.7K resistor across the cut you made.
3. Using a SPST switch, one side of the switch goes to the cut-side of pin #16.
4. The other side of the switch goes to pin #9 of the PLL. (8 volts)
When you apply the 8 volts, this pulls pin #16 high causing the 10 kc jump up.
Note that this will not work on all channels.

For a 10 Kc DOWN jump only:
1. Ground pin #16 using a SPST switch. No cut to the PLL is necessary.
Pulling pin 16 low will cause it to jump down 10Kc.
This too will not work on all channels.

For a 10 Kc UP and DOWN switch:
Perform the trace cut/resistor addition described above.
Use a SPDT switch and wire as follows:
1. Center of switch goes to pin #9 of PLL (8 volts)
2. One side of switch goes to the cut side of pin #16.
3. The last side goes to pin #18 of PLL (or ground)
This will allow you to jump 10Kc up or down.

COBRA 140,142 GTL , PRESIDENT P-400, UNIDEN WASHINGTON-(8719 PLL)

MODULATION: Remove R104 or TR32
AM POWER: VR6
SSB POWER: VR7
"RX" METER: VR1
"TX" METER: VR10
SQUELCH: VR2
TX FREQ.: VR3
CARRIER BAL: VR5
DRIVER BIAS: VR8
FINAL BIAS: VR9
MOD. METER: VR12

POWER TWEAK
1. Remove TR32
2. Replace R99 (10k) with a 2.2k
3. Replace R94 (10k( with a 2.2k
4. Re-tune coils L36,L37 for maximum forward AM power.

CLARIFIER:
1. Remove R187
2. Remove D36
3. Jumper D35
4. Follow the RED WIRE from the clarifier control to the PC board and UNSOLDER it.
5. RESOLDER this RED WIRE to pin 3 of regulator IC MB3756.
6. Follow the ORANGE WIRE from the clarifier control to the PC board and UNSOLDER it.
7. RESOLDER this ORANGE WIRE to the PC board ground.
NOTE: The Orange and Red wires may need to be reversed in some radios for this to work right.
8. Re-align center slot by adjusting CT3.
If all went well and you didn't smoke your radio, you should slide about 1 Kc up and 4 Kc down.

NEED MORE SLIDE??: Install a 5.6uH choke on the banded end (grounded end) of the varactor diode D37 or replace D37 with a super diode.

CHANNEL TWEAKS:

EASY TWEAK: Install EXPO 100 kit "B".
FOR THE DRILL HOLES ALL OVER MY RADIO LOVERS...:
1. Replace 11.1125 crystal with a 11.3258 crystal.
2. Isolate the ground pin 10 of the MB8719 PLL by cutting the PC trace.
3. At this point, turn your radio on and check to varify that all channels are locked in and working. If it is not, adjust these in the following order:
a. CT3 for USB.
b. L20 for LSB.
c. L19 for AM.
4. Install a SPST switch between pins 11 and 12 of the MB8719 PLL
5. Install a SPST switch across the cut you made to isolate pin 10.
6. Check all connections for shorts.
7. Check to make sure everything is working before you drill holes for the switches!

ROAD MAP:

SW1 / SW2 DOWN: NORMAL 1-40
SW1 UP / SW2 DOWN: (ch.15-27) 26.815 to 26.955
SW1 UP / SW2 UP:
1= 27.605 6= 27.505 11= 27.565 20= 27.525
2= 27.455 7= 27.515 12= 27.585 23= 27.575
3= 27.465 8= 27.535 13= 27.595
4= 27.485 9= 27.545 14= 27.605
5= 27.495 10= 27.555 16= 27.475
SW1 DOWN / SW2 UP: (ch. 1-40) 27.605 to 28.045
 

COBRA 2000 GTL

POWER TWEAK:
1. Remove TR24
2. Replace R126 (10k) with a 2.2k
3. Replace R124 (10k) with a 4.7k
Re-tune coils L37,L38 for maximum forward power.

REPAIR TIPS:

Frequency counter eratic:
1. Find D528 (5.7v 1/2W zener) located in the freq. counter module.
2. Replace it with an NTE-136A 1 watt zener.

Transmit on SSB, but not on AM:
1. Find the regulator TR41 (2sc1419) and remove it.
2. Replace with a GE-66(10 amp) or an NTE-152 (7 amp)

Channel display glows dim after radio is shut down, freq. counter may be unstable
1. Find Fet-501 and Fet-502 located in freq. counter module and replace them.
Older models use: 2SK19GR
Newer models use: 2SK192A

CLARIFIER:
1. Remove R44 and D52.
2. Remove R174 and put a jumper in its place.
3. Follow the YELLOW wire from the clarifier control to where it connects to the PC board and UNSOLDER it.
4. Solder this YELLOW wire to the PC board ground.
5. Follow the RED wire from the clarifier control to where it connects to the PC board and UNSOLDER it.
6. Solder this RED wire to pin #3 of MB3756 regulator.
7. Find the BROWN wire on the clarifier control UNSOLDER it, and tape it out of the way.

No smoke? Then you must have about 1Kc slide up and 5Kc down!
 

Uniden WASHINGTON (858 pll)

POWER TWEAKS:
(Mike circuit changes:)
1. UNSOLDER banded end of diode D21 and lift up.
2. UNSOLDER banded end of diode D22 and lift up.
3. SOLDER a 4.7 k resistor across where D21 and D22 was unsoldered.
4. Replace R78 (27k) with a 56k.
5. Replace R84 (4.7k) with a 2.2k.

(Transmit circuit changes:)
1. Replace C174 (56pF NPO) with a 82pF NPO ceramic capacitor.
2. Replace C173 (180pF NPO) with a 220pF NPO ceramic capacitor.
3. Re-tune coils L32,L30,L29,L28 and VR8 for maximum forward AM power.

CLARIFIER:
1. UNSOLDER and remove D30.
2. UNSOLDER and remove D29.
3. Add a jumper in the holes from where you removed D29.
4. Cut the end of R119 that is closest to D29.
5. Add a jumper wire from R119 (the cut end) to the banded end of D44.
6. Follow the PURPLE/WHITE wire form the clarifier control to the PC board and UNSOLDER IT.
7. Resolder this wire to the PC board ground.
8. If all went well, you should slide 1 kc up and 3 kc down.

KNOWN BUGS:
The AM regulator 2SC1419 is WEAK. UNSOLDER it and toss it in the trash.
Replace it with a GE-66, ECG-152 or a NTE-152.
Relay buzzes on SSB, no am transmit, lights go dim, or the fuze pops sometimes?
Replace C179 ( a 2.2uF 25v tantalum cap located near finals) with a standard 2.2uF electrolytic capacitor.
PAY ATTENTION to the "+" and "-"!!!
 

Uniden PRO-510XL,PRO-500D,PRO-520XL

MODULATION: Cut D14
AM POWER: L6,L5
VR1: Squelch
VR2: TX meter
VR3: RX meter
VR4: RX IF gain
 

Uniden PC-66,PC-66A

POWER TWEAK: (ALSO WORKS ON: Uniden AR44,AX44,AR711)
1. Replace R76 (3.3k) with a 1k.
2. Replace R43 (10 Ohm) with a 2.7 Ohm.
3. Replace R108 (1 Ohm) with a .47 Ohm.
4. Re-tune coils L13,L10,L9,L8 for max forward power.
 

ZACHARY T. (new model w/2816 pll)

MODULATION: VR6 or cut D16
AM POWER: L13,L12,L11
RX COILS: L1 thru L8, VR1
SAMS PHOTOS: #223,229,235,243,272,282

CHANNEL TWEAK:

1. Use EXPO 100 kit "A" for 26.515 to 27.855 coverage.
2. Isolate pin 9 on the pll for a 5kc drop.
 
 

1.Remove the top of the case (The Part that does not have the speaker on it) and locate the wire (is usually green or red about 2  inches long)toward the front of the radio.

2. Unsolder it from the ground and the two pins. After you have removed this wire make sure there is no solder connecting the two pins together.

3. Find the connector toward the front right of the radio labeled 10K and reconnect this plug to the connector on the  circuit board. (NOTE: This plug may already be attached when you get your radio.)

4. All thats left to do is put the case back on and your done.

Modulation Mod

VR14 may have been adjusted or TR53 may have been cut or removed

Variable Alignment Points That May Have Been Adjusted

VR1=AM S-Meter VR2=SSB/CW S-Meter VR3=SSB Squelch VR4=AM Squelch Range

VR5=FM Deviation VR7=Carrier Balance VR8=RF Transmit Meter VR10=1st Final TX Bias

VR11=Driver For TX Bias VR12=ALC For SSB Power VR13=AM High Power

VR14=AMC for AM Modulation VR16=AM Low Power VR20=2nd Final TX Bias

VR21=Frequency Adjustment Carful on this one

Euro 3900 Channel Modification
 
 

Remove the bottom cover, be carful not to pull the speaker wire out. There is a black plastic rectangular plug (CN5) which is in the front center of the radio right in front of the gold colored crystal. Using small needle nose pliers, pull the plug off and
reinsert it in the next slot. You now have the 11 meter band on Band D. NOTE: You also have to pull out the calibrate knob
to get the extra channels.

Euro 3900 Power Mod

Locate the trim caps labeled "AMP", "MOD" AND "SSB". Turn these adjustment screws all the way to the right. These caps are on the same board as CN5, but on the oppisite end.  Thats all there is to it. You should see around 15 watts on AM and 25 watts on SSB
 

This chip can be found in many radios. This mod might work on the SSB units also.

G.E.

3-5804D,3-5811B,3-5812A,3-5813B,3-5819A

Midland

76-858,76-863,76-886,77-830,77-838,77-849,77-857,77-882,77-888,77-899,77-955,77-963

And just about anything with a PLL 02A chip in it.
The 23-channel radios will give different channels.

1)Cut the Trace going to PIN #11.
2)Solder a 3.3 K resistor across the cut.
3)Solder 1 leg of a SPST switch to PIN #8.
4)Solder the other leg to PIN #11.

1 - 26.805 . . . . . . . 4 - 26.845 . . . . . . . 7 - 26.875
2 - 26.815 . . . . . . . 5 - 26.855 . . . . . . . 8 - 26.895
3 - 26.825 . . . . . . . 6 - 26.865 . . . . . . . 9 - 26.905

 

1)Cut the Trace going to PIN #10.
2)Solder a 3.3 K resistor across the cut.
3)Solder 1 leg of a SPST switch to PIN #9.
4)Solder the other leg to PIN #10 after the resistor.

This will give you 26.645 to 26.745 Mhz on channels 1 - 38.
 
 

1)Cut the Trace going to PIN #9.
2)Solder a 3.3 K resistor across the cut.
3)Solder 1 leg of a SPST switch to GROUND.
4)Solder the other leg to PIN #9 before the resistor.

This will give you 27.425 to 27.705 Mhz on channels 12-38.

 

1)Cut the Traces going to PIN #10 and PIN #9.
2)Solder a 3.3 K resistor across the cuts.
3)Using a DPDT Center-Off type switch solder wires from the PLL to the back of the switch as shown.

When the switch is UP.
This will give you 26.435 to 26.7455 Mhz on channels 10 - 38 .

When the switch is DOWN.
This will give you 26.755 to 27.055 Mhz on channels 10 - 38 .
 
 

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+ 10 KHz Jump Switch

 

1)Get a SPST switch and mount it in the radio.
2)Find IC 6 & 7 by the PLL chip. You will see J25 and J27
3)Solder a wire from one side of the switch to J27.
4)Remove the jumper that is J25.
5)Install a 4.7k Ohm resistor in its place.
6)Solder a wire from the other side of the switch to J25.(see Picture)
5)That's it .Flip the switch to jump up one channel.

Channel Expansion

 

1)You will need 3 SPST switches and mount them in the radio.
2)Find the PLL MC145106.
3)Locate pin # 10 and cut the trace going to this.
4)Switch #3 will be soldered to the cut traces on pin # 10.
4)Solder wires to the other 2 switches as in the picture above.
5)That's it!

ALl the switches down will give the normal channels of the radio.

 With the radio in 'HIGH' band and switch 1 UP , 2 DOWN , and 3 DOWN:

 You get 27.845 - 27.955 on channels 10 to 19.

 With the radio in 'MID' band and switch 1 UP , 2 UP , and 3 DOWN:

 You get 27.925 - 28.065 on channels 1 to 12.

 With the radio in 'HIGH' band and switch 1 UP , 2 UP , and 3 DOWN:

 You get 28.045 - 28.155 on channels 27 to 38.

 With the radio in 'HIGH' band and switch 1 DOWN , 2 DOWN , and 3 UP:

 You get 26.135 - 26.575 on channels 1 to 40.

 

Frequency Expansion

 

1) This is one of the more difficult mods out there.
2) Open the bottom cover of the radio .
3) Find the PLL Board. Its the one with the 64 pin chip on it.
4) At the front of this board by the PLL chip ther are 2 resistors R540 and R539.
5) Cut them.
6) Close the radio up. Turn it on.

Tweak and Peak

 

Audio limiter - R247
AM Power - VR 111
SSB Power - VR 103

RIT Modification

 

1)Remove top and bottom covers.
2)On the top of the main board find D140.Cut it.
3)Solder one end of a 10 OHM resistor to the location in the picture below.
4)Take a 7.5v zener diode and solder the end without the band to the small brass shield.
5)Now solder to other end of the diode to the open end of the resistor.

6)Find the PC Board that is behind the RIT Knod

7)Cut the trace as you see in the picture above.
8)Solder a wire(See the green wire in the pics) from the point that the diode and resistor meet togeteher to the bottom of the board where you made the cut.

Aligning the RIT

 

1)Place the radio so that the smaller PC Board is facing up.
2)Turn it on and dial up 28.000 MHZ and put the rit dead center.
3)On the samller PC Board locate J502.(upper right)
4)Pull the grey cable off the board and connect it to your frequency counter. (Sorry you can't use them $49 dollar specials from copper. You have to have a frequency counter with a probe on it) 5)Hook up the probe and if it should read 38.695 +/- 100 Hz.
6)If not then adjust L501.
7)Put the radio back together.You shound have about 6KHz of slide.

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COBRA 32 XLR , 86 XLR and Tram D42

1) Mount 2 SPST toggle switches in a good loacation on the radio.
2) Locate PIN #8 of the PLL and unsolder the green wire and remove any excess solder .
3) Cut the trace that is connecting pin #8 to the PCB.
4) Resolder the green wire to the other side of the cut trace.
5) Now take a 100k resistor and solder one end to pin #8 and the other end to ground on the PCB.
5) Solder the wires onto the switches and pins of the chip like in the diagram above.

With Switch #1 up and Switch #2 up will be the low channels

.3 - 26.665________ 15 - 26.815
.4 - 26.685________ 16 - 26.835
.5 - 26.695________ 17 - 26.845
.6 - 26.705________ 18 - 26.855
.7 - 26.715________ 19 - 26.865
.8 - 26.735________ 20 - 26.885
.9 - 26.745________ 22 - 26.905
11 - 26.765________ 23 - 26.935
12 - 26.785________ 24 - 26.915
13 - 26.795________ 25 - 26.925
14 - 26.805________ 26 - 26.945

11 - 27.405________ 19 - 27.505
12 - 27.425________ 20 - 27.525
13 - 27.435________ 21 - 27.535
14 - 27.445________ 22 - 27.545
15 - 27.455________ 23 - 27.575
16 - 27.475________ 24 - 27.555
17 - 27.485________ 25 - 27.565
18 - 27.495________ 26 - 27.585

COBRA 138 139 XLR (OLD) PRESIDENT GRANT, WASINGTON,MADISON , ROYBN 510 , 520D ,TRC-449 457 AND 458

1)FIND PIN #19 OF THE 858 CHIP.THIS PIN WILL BE CONNECTED TO GROUND WITH A SMALL TRACE. CUT THE TRACE AND SOLDER A 4.7K OHM RESISTOR ACROSS THE CUT .

2)FIND PIN#21 AND DO THE SAME AS YOU DID TO PIN #19.

3)INSTALL A SPDT/CENTER OFF TYPE AND ALSO A SPST SWITCH IN THE CHASSIS OF THE RADIO.SOLDER THE WIRE FROM THE CHIP TO THE 2 SWITCHES AS IN THE PIC ABOVE.

4) TURN THE RADIO ON AND SEE IF ALL THE CHANNELS WORK.IF NOT THE YOU WILL NEED TO "BROAD BAND" THE RADIO.CUT THE 2 TRACES AND INSTALL THE 2 JUMPERS AS IN THE PIC BELOW.

Now with s1 up and s2 center this is the reg CB
With s1 up and s2 up will be 27.455 to 27.805 on CH. 8-40
With s1 up and s2 dn will be 27.855 to 28.005 on CH.8-20
With s1 dn and s2 up will be 26.455 to 26.805 on CH. 8-40
With s1 dn and s2 dn will be 26.855 to 26.955 on CH.8-16
With s2 dn and s2 center will be 26.085 to 26.45 on CH. 11-40

1) Mount 2 SPST toggle switches in a good loacation on the radio.
2) Locate and unsolder the 11.1125mhz Crystal and replace it with a 11.3258 mhz crystal.
3) Locate pin 10 of the mb8719 chip.Cut the trace that is connected to it.
4) Solder the wires onto the switches and pins of the chip like in the diagram above.

The mod is basically the same for these radio EXCEPT that there is no PC trace going to pin#10 on this PLL.

On the Cobra 2000gtl you will find a MB8734 pll replace it with a MB8719 PLL

Clarifier Modification

1)Cut d-52 and r-148.Find r-174 and solder a wire across the resistor.
2)Find the RED wire that comes off the clarifier control and cut it just before it connects to the PCB. Take that wire and solder it to GROUND on the PCB
3)Cut the orange wire just like the red wire but solder this wire to pin # 3 if IC-4 the MB3756 ic regulator.

This should give you about 5 khz is slide on this radio.

1) Cut R44 and D52.Find R174 and jump it .
2)Follow the red wire from the clarifier knob and cut it just before it connects to the PCB.Take this wire and solder it to Ground.
3)Find the orange wire from the clarifier and cut it the same.Then solder it to pin #3 of the mb3756 ic.

This should give you about 6khz of slide.

COBRA 2000 GTL

1) Cut R44 and D52.Find R174 and jump it .
2)Follow the YELLOW wire from the clarifier knob and cut it just before it connects to the PCB.Take this wire and solder it to Ground.
3)Find the RED wire from the clarifier and cut it the same.Then solder it to pin #3 of the mb3756 ic.
4)Cut the brown wire off the clarifier knob.

COBRA 140GTL,142GTL,PRESIDENT WASHINGTON,McKINLEY,AND P400

 

1)Cut r187 and d36
2)Find the red and orange wires commong off the clarifier knob.Cut them where they connect to the PCB.
3)Take the red wire and solder it to pin #3 of the mb3756 IC.Solder the orange wire to PCB ground.

NOTICE:On some radios the red and orange might have to be reversed to slide in the right direction.

Cut the trace going to pin #16 and bridge it with a 4.7k resistor. Then use a SPDT center off switch solder the middle terminal of the switch to the pin before the cut. Next solder one side to a 5 volt dc source and the side of the switch to ground or pin #18.

COBRA 142 AND 140GTL

MOD.-R104 AM PWR- VR6 SSB PWR-VR7

COBRA 2000 148GTL PRESIDENT WASHINGTON MADISON

MOD.-R131 AM PWR.-VR10 SSB. PWR-VR11

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1) Lift anode of D-30 and connect a 5.6 uH choke in series.
2) Cut D-32.
3) Cut both traces on the PCB going to the clarifier .
4) Solder one wire to PCB ground.
5) Solder a wire from the other cut trace to an 8 VDC source
(note: 8 volts can be found on the cathode of D-50)
6)This should give you 5 kc of slide.If more slide is wanted then change D-30 to a super slide doide.

1)Find the backside of the clarifier knob.
2)Solder the bottom pin to GROUND. 3)Solder a wire to the top pin of the PCB.
This pin should be cut loose from any traces going to it!)
4)Solder that wire to an 8VDC source.This can be found on the second jumper behind the PLL chip(IC-2).
5)Cut D-25.

1) Cut D-25.
2) Cut D-32.
3) Cut both traces on the PCB going to the clarifier .
4) Solder one wire to PCB ground.
5) Solder a wire from the other cut trace to an 8 VDC source
(note: 8 volts can be found on the trace that connects R-107 & R-106
6)This should give you 3 kc of slide.If more slide is wanted then jump D-24 with a piece of wire.(Sometimes it works)

1)Unsolder the PLL chip.UPD2824 or D2824.
2)Throw it away.Its can't be modified.
3)Solder in a new PLL UPD2816.
4)Connect pin #20 to pin #21 GROUND.
5)Solder a wire from pin #9 to one side of a SPST switch.
6)Solder a wire from PCB GROUND to the other side of the switch.
7)If all goes well this should give you 27.420 - 27.860 Mhz.
Yes, i know 27.420 in between the channel SO use the clarifier for the 5 kc offset.
8)If you can't get all the frequency coverage then adjust L-14 the VCO coil.

VR 10 is AM power
VR 6 is ALC
VR 5 is AM Modulation
VR 7 is RF Power meter
VR 1 is S-meter adjust.

Frequency Expansion

 

1) Unplug the radio and turn it on.(This is to drain the power out of the cpu)
2) Remove the covers off of the radio .
3) The radio has a removable plug on the front board with a blue jumper on it.
4) Disconnect this plug.
5) Close the radio up. Turn it on.
6) The radio should now have 6 bands (A-F). Use the chan 9 button to change bands.

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President Grant Export Mods

1)The switch needed is a SPST/CENTER-OFF type.Mount this in the radio somewhere.
2)Find the PLL MB8719 chip.Find pin #11 and cut the trace going to it on the foil side of the PCB.
3)Solder a 4.7k ohm resistor across the cut that you just made.
4)Now you are ready to attach the wires from the switch to the locations on the PCB.
5)Solder a wire from the top pin on the switch to PCB ground.
6)Solder a wire from the middle pin on the switch to pin #11.
7)Solder a wire from the tbottom pin on the switch to pin #9.
(If you do not get ALL the new channels adjust the VCO coil,l-18)

 With the switch in the UP position:

 

12 = 27.875 17 = 27.935 22 = 27.995 26 = 28.035 13 = 27.885 18 = 27.945 23 = 28.025 27 = 28.045 14 = 27.895 19 = 27.955 24 = 28.005 28 = 28.055 15 = 27.905 20 = 27.975 25 = 28.015 . 16 = 27.925 21 = 27.985 .  

With the switch in the CENTER position is regular channels

 With the switch in the DOWN position:

 

12 = 26.335 17 = 26.395 21 = 26.455 24 = 26.475 13 = 26.345 18 = 26.405 22 = 26.465 25 = 26.485 14 = 26.355 19 = 26.425 23 = 26.495 26 = 26.495 15 = 26.365 20 = 26.445 27 = 26.505 16 = 26.385 .  
 
 

President Grant SLIDER mod

1) Cut D-45.
2) Find D-79 and jump it (Solder a wire across it)
3) Remove r-120 and replace it with a 470 ohm resistor.
4) Find the BLUE wire from the clarifier knob and cut it just before it connects to the PCB. Solder it into the hole that is next to where R-120 is.
5) Find the GREY wire from the clarifier knob and cut it just before it connects to the PCB. Solder it to a constant 8.5 volt supply.(This can be the center pin of TR-39 )

Hopefully this should give you about 3 khz of slide.

 

President Grant MIKE wiring

 
 
 

President Grant 'peak & tweak'

MODULATION - Adjust VR-14
AM POWER - VR-13
SSB POWER - VR-12

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SEARS ROADTALKER BASE/MOBILE

1)Open the radio and you will find a metal case around the pll chip.unsolder this. 2)Cut the trace around pin 9 and 8 . 4)Solder a 4.7k resistor from pin 8 to ground. 5)Install a 6 posistion/ double pole rotary swicth in the radio.then run wires (the red lines) from the switch posistions to the locations on the pc board. 6)Solder a 1n914 diode from pin 1 to pin 4 on the switch. 6)Solder a wire from pins 2A to 3A to 4A to 5A.

Adjust t302, the VCO,so that the radio will TX/RX on all the extra channels. HINT:USE A PLASTIC TUNING TOOL TO MAKE THIS ADJUSTMENT OR YOU WILL BREAK THE COIL!!

POSITION 1

Channel 1 to 40 is 26.485 to 26.925

POSITION 2

All the regular CB channels

POSITION 3

Channel 12 to 27 is 27.425 to 27.595

POSITION 4

Channel 1 to 40 is 27.605 to 28.045

POSITION 5 AND 6 will give regular CB Channels

CLARIFIER MODIFICATIONS

1)Find the green wire coming off the FINE TUNING control.Follow the wire to the pc board where it connects and unsolder it.
2)Find the RED wire behind the meter display and solder it to that location(there is 8VDC there)
3)Find the BLACK wire from the FINE TUNING control and unsolder it from the PCB.
4)Solder this wire to PC GROUND .
5)Find the PURPLE wire from the FINE TUNING control and unsolder that from the PC board.
6)Solder this wire to the point on the PC board where R303 and the cathode,the end with the band around it! , of D301.
 

This mod will give you about 3khz up/down off the "channel".
If you move the clarifier and the radio "drops out" you will need to JUMP d301 and put the purple wire back to where it was.