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CB MODS  
 
Modulator modules---beware!!!

It's a module that was "supposed" to increase your modulation and let your radio 'swing'.
Example: papa-mod for a superstar 3900....it only had a 390k ohm resistor in it!!
There were power wires and a wire that connected to the mike plug....they didn't connect to anything inside the module!
All the module does is replace a resistor in the radio (r238...a 5.6K resistor in line with the variable resistor that adjusted the am power) with the one in the module.
I am telling everyone  so that no one else will get suckered out of $15.00 or more getting one of these things.
 

 

SUPER-TALK - THE GREAT RIP OFF!!!

Want to know what's inside?

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
 

 

 Galaxy Radios

Galaxy 44V
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.

It should be able to go from 28.300 Mhz. to 28.500 Mhz. ULATOR" ?
?? Here is what another reader wrote:
Super Star 3900 Gold and Cobra 148GTLX Gold

(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."

The above is compliments of "Doug Davis" <[email protected]>

SuperStar 3900

 
+ 10 KHz Jump Switch

 

< HEIGHT=305 WIDTH=393>
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

 

< HEIGHT=305 WIDTH=393>
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 25 GTL/LTD/CLASSIC

SAMS PHOTOS: 207
AM LIMITER: D-9
POWER TWEAKS:
1. Change R76 (3.3k) to a 1k (located near mike socket)
2. Change R43 (10 Ohm) to a 2.7 Ohm.
3. Change R108 (1 Ohm) to a .47 Ohm.
4. Replace stock final with a 2SC1969 transistor.
5. Re-tune coils L10,L9,L8 for maximum forward power.

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 #1:
1. Change R58(10 Ohm) to a 2.7 Ohm.
2. Change R123(1 ohm) to a .47 Ohm.
3. Re-tune L14,L13,L12 for maximum forward power.

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

POWER TWEAKS:
1. Remove TR24
2. Change R126 (10k) to a 2.2k
3. Change R124 (10k) to a 4.7k
4. Re-tune L37 and L38 for maximum AM forward power.

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

MODULATION: VR12 or Cut R131
AM POWER: VR10
SSB POWER: VR11
AM SIGNAL METER: VR1
SSB SIGNAL METER: VR2
SQUELCH: VR3
CARRIER BALANCE: VR4
TX FREQ.: VR5
TX METER: VR6
MODULATION METER: VR7
FINAL BIAS(50 Ma): VR8
DRIVER BIAS(25 Ma): VR9

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)

MODULATION: VR7 or cut D23
AM POWER: VR8
SSB POWER: CT7
RX COILS: L3 thru L8
TX COILS: L32,L30
SAMS PHOTOS: #126,127,128,170,171,176,179,200,207

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

POWER TWEAKS:
1. Locate the 2.7 ohm resistor in front of the final bias resistor(15 Ohm w/RF bead) and change it to a .47 Ohm. (DO NOT change the 15 Ohm resistor!!)
2. Re-tune L9,L6,L5,L4 for maximum forward power.

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


 

Uniden PC-66,PC-66A

MODULATION: VR5 or cut D9
AM POWER: L13,L10,L9,L8

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)

POWER TWEAK:
1. Remove C128 (.47uF).
2. Remove TR16.
3. Replace R132 (1k) with a 470 Ohm.
4. Replace R50 (3.9 Ohm) with a 1 Ohm.
5. Re-tune coils L13,L12,L11 for maximum forward power output.
6. Jumper C61 with a 67pF capacitor.
7. Replace TR10 (2SC2029) with a 2SC1969 then tune L16,L17 and spread L14 For even power across band.
8. Remove D13 and replace with a jumper. (This supplies more power to final)

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.
 
 

 
77-285 MIDLAND
 
There are two printed ciruit boards for the  77-285. You must first determine which you have.
Circuit board "A"
This board can be identified because D18 has been cut.To restore full power simply resolder D18 or replace it.
Circuit board "B"
On the "B" circuit board D18 is intact (has not been cut out).To restore full power, locate D18
and trace the etch. Put a solder bridge between the open pads.
 
Channel Conversion:
STEP 1. Take the bottom portion of the case off and unplug the speaker.
STEP 2. With the bottom of the case off, turn the radio over and in this position the  Midland name should be upside down. Tilt the chasis      forward toward the face plate. As you  look at the inside panel the LC7232      IC chip
should be readable and pointing toward you (upper right corner).      You need to open
solder bridges 5 and 6 from left of the chassis(bottom left).
 
 
77-290 MIDLAND
 
STEP 1 Remove top and bottom cover.
STEP 2. Prepare an 8" small gauge jumper wire Tin both ends.
STEP 3. Remove the 1K ohm chip resistor on the radio front panel
STEP 4. At the removed resistor location, solder the  prepared jumper to the pcb pad nearest the center of the radio.
STEP 5. Solder a 1K ohm 1/8 watt lead resistor to the other end of the jumper.
STEP 6. Solder the free end of the resistor to the emitter  lead (lead nearest the rear of the radio) of Q61.
STEP 7. Turn the radio over so the bottom of the pcb is facing up and the front is closest to you.
STEP 8. Locate chip resistor R63 and remove
 
240 Channels:
Press and hold "DW" and "9" then turn radio on. Select bands by using the "19" button.
To set 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.
 
Microphone Gain:
1. Chip resistor R138 controls mic gain decreasing the value of the resisitor increases the gain. Generally have
270 ohm, the value can be as low as 150. If too much gain is used oscillation may occur.
 
 
TRC485
 
Audio Limiter cut RV5 or cut R111 4.7K resistor
No SSB Control for ALC
AM Power Level RV 10
Open Clarifier:Remove the 5 volt switched  voltage from clarifier control. (REMOVE THE
FACE  PLATE TO CUT THE TRACE). Solder 4.7k resistor from SJ32 to the closest leg  of clarifier
control. snip d21 by crystal on main board. Jump surface mount  resistor 181 by clarifier control
 
 
 
Galaxy DX77HML Extra Channels Modification
 

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
 

 

 
 

PLL 02A MODS

 
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
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