|Galaxy DX-959 Mods|
|10kc Switch Modification|
|Clarifier (Unlock) Modification|
|Clarifier/Frequency Counter Realignment|
|Microphone Wiring Pinouts|
Galaxy CB Radio DX-959 Mods
PLL: RCI 8719
Modifiable -Can be expanded to include the full range of frequencies this radio is capable of from 26.695MHz up to 27.965MHz.
Note: Additional channels can be acquired by "broad-banding" this radio. However, even though Galaxy has "hinted" information regarding the broad-banding procedure, it has yet to be tested.
Microphone Gain Modification:
The DX-959 has plenty of modulation to spare but it lies dormant as the factory settings "choke" it's true audio capability. This can be remedied, however!
Q39 is the modulation limiter for the DX-949 and DX-959. However, don't be foolish by removing the limiter. Why? The limiter is there for a reason! Removing the limiter altogether on the DX-959 will cause severe garbling in sideband mode. Instead, place a 1k resistor in series with the emitter leg of Q39. This used in conjunction with finding a satisfactory balance between adjusting VR16 along with the Mic Gain on the radio, and using a good amplified microphone will provide as much modulation as desired.
Many 959 owners report excellent results by just peaking VR16 and balancing their Mic Gain on the radio with an amplified microphone (without adding the resistor). All I did with my radio (no resistor) is peaked it just right with the screwdriver and now it's LOUD and PROUD. All without clipping the mod limiter. That's simply just a no, no with any radio!
Channel Expansion Modification
1. First, remove power to (unplug) the radio. Remove the bottom chassis cover of the radio.
2. Locate J33 near the left-front of the main board. It is partially hidden under the small PCBs just above it. This is the controller you will be working with.
3. On J33, locate the wires going into the P5 (Yellow) & P6 (Gray) positions and note their colors. These are the main frequency control lines. Follow both to each end and cut each wire at a convenient spot where it will be easiest to work on them.
4. Install an SPST switch between the gaps in each wire. Do not cross the wires. In other words, you want each switch in-line with each wire. This will effectively "open" or "close" each wire's circuit associated with the PLL. This provides the extra channels. Locate the switches anywhere you'd like as long as they are easily accessible. One option is to use any existing switch located on the front panel of the radio due to the fact that it is so cluttered with switches and knobs already.
5. Replace the bottom cover of the radio.
Your radio should now be fully expanded to operate on the expanded frequencies. Here is a link to the roadmap for the above new frequencies.
~ Another option~
Is to "tap into" the P5 & P6 lines with a 4-wire telephone cord (or equivalent). The cord would then route through one of the factory holes in the back of the radio to the SPST switches mounted on a small project box on the other end. No cutting or drilling anywhere on the radio is required. E-mail me if anyone wants step-by-step instructions. Although this is a viable alternative, the trade-off is that some people might not like the fact that they have an external "remote control" box and cord for controlling the extra channels -something about their radio looking "obviously illegally modified". Whatever. If "Uncle Charlie" ever suspects that your radio is transmitting illegally they will find out anyway. Get it? Regardless, if the radio is to be used as either a base station or mobile, this method should definitely be considered and not overlooked. Besides, everyone who has seen my radio wired this way says it looks wicked. ;o) -Thanks, tac0meat for suggesting this idea!
In light of the recent addition of the 10kc switch mod, I elected to take the option above (4-wire telephone cord) one step further. Since the 10kc mod also requires a switch, I decided to add the new one to the project box as well. This gives complete control over all of the frequency mod functions in one handy control unit. Unfortunately, this also leaves the issue of what to do about the required three new wires. However, after a bit of brainstorming, I found the problem is easily solved courtesy of a 3 foot length of Cat 5e Twisted Pair computer network patch cable! These cables are readily available, and typically have 4 pairs (8 wires total inside one "cable") of the correct gauge wire. So yes, I had to de-solder and re-solder on both ends of the phone cord in order to swap out the old vs. new cables -but the effort was definitely worth it. The only remaining problem is the different colors of the new wires, but careful thought regarding the new different colors and their "old" equivalents... and voila! BTW, due to the slightly thicker new cable, I ended up having to ream out one of the existing holes in the back of the radio just a touch after all -can't tell, though. Oh well, I'm still very satisfied with the results, though.
10kc Switch Modification:
*Note: As I verified (successfully) the following mod by performing it myself, I ran into some degree of difficulty -especially with cutting the trace as specified. This is a lot trickier than it sounds due to the placement, size, and proximity of the surrounding traces and solder points. I recommend exercising a great deal of care and by all means, TAKE YOUR TIME with this mod! Once you take a look at what you're up against you'll see what I mean. If you have shaky hands or even the slightest doubts, it would be wise to have someone else you trust perform the mod for you. It's just not worth messing up a neighboring trace and well, you know what that means... :(
Here are the steps to perform this mod:
1 - Locate pin 16 of the MB8719 PLL chip.
2 - Cut the trace on pin 16 and place a 4.7K ohm quarter watt resistor.
3 - Next find a miniature SPDT three position, "center off" switch. You can get these at Radio Shack.
4 - Solder a wire from the center contact on the switch to the chip side of the resistor that you just placed across the cut of pin 16.
5 - Take another wire and solder it to one of the remaining contacts on the switch and run it to pin 18 of the PLL or DC ground.
6 - Solder a wire to the remaining switch contact and run this wire to pin 9 of PLL.
The center position is for normal channels. However, depending on the currently selected channel, the two switch positions will allow you to go to the channel immediately above or below thus allowing access to the desired "A" channel frequencies. See the roadmap for the specifics on using this mod.
By popular demand, here are some pics of the channel & 10kc mods:
~Broad-banding the 959~
This mod is not recommended for the novice.
Greedy for more channels? Speaking for myself, I'm perfectly happy with the nice batch of new frequencies acquired in the P5/P6 mod above. After all, I really can't work with many more lower or higher frequencies without having to retune my antenna anyways. My match goes up significantly at both extremes as it is! But if you absolutely positively MUST tinker further, then read on...
Additional channels (with slight variation of coverage) can be made available which requires the use of SPDT switches instead of SPST switches. This also requires the attachment of the P7 control line to the switch so that the line coming from the PLL on the main board is switched between the original control line (P5 or P6) and P7.
Some people feel this mod is really more trouble than it's worth (and may be potentially dangerous) since the P5/P6 channel mod in the steps above safely provides more than enough extras. Ever compare it to the old Cobra 148 GTL channel mod? The Galaxy ends up with roughly the same extra frequencies!
Note: According to Galaxy, broad-banding (opening the PLL to it's fullest potential) the DX-959 simply requires the removal of diode "D3" on the VCO module. The earlier radios had this diode. If it is not there on yours, then you have the later model which already comes without it. Another alternative is to replace c296 with a .0015uf capacitor. Two different techs say either method will work -providing the VCO doesn't lock up... it's possible, but it shouldn't. :o)
If anyone has already done this mod or has further related info and/or corrections, please e-mail me the details.
*I have not done this mod so don't hold me responsible if you try it and your radio blows up! :o)
A Better Alternative: VIAGRA!!!
The new "Viagra" channel boards are a much safer and depending on the channels you want, a better way to go. These kits are readily available, rather simple to install, and you get 120 channels. However, as you can see below, the range differs from the P5 / P6 channel mod above.
P5 / P6 mod range: 26.695 to 27.965
(Goes higher than the Viagra mod, but not as low)
~ 23 channels below and 49 above (112 channels total) ~
Viagra mod range: 26.515 to 27.855
(Goes lower than the P5 / P6 mod, but not as high)
~ 40 channels below and 40 above (120 channels total) ~
So basically, there are only 8 channels missing with the P5/P6 mod.
Clarifier (Unlock) Modification:
Much controversy has centered around this mod. Many people complain that it simply doesn't provide enough "slide" to do much of anything -especially reach the "A" channels. In my own experience I tend to disagree. Yes, there are remedies to this by tinkering with the clarifier circuit in various ways, but why? Oh, I've heard it many times... Some people claim that "unlocking a clarifier to slide at least a full channel up or down is the only way to go". But wait, isn't that what the channel selector knob is for?!?! In reality and simplicity, the purpose of having an unlocked clarifier for talking on sideband is to match your transmitting frequency with the other person's receive frequency -thus making communications much easier. In other words, if your clarifier is unlocked and you tune them in on receive, you will also transmit on the same frequency. And this mod excels at accomplishing that task very well. Still want to get to the "A" channels? Well, there's a 10kc mod for that as well. First things first. Read on...
There are currently several known ways to unlock the clarifier on the DX-959. Here are two:
First, remove power (unplug) to the radio. Remove the bottom chassis cover of the radio.
Remove JP195 and JP196.
Connect a jumper wire between J14 pin +8V and J9 pin F1.
Remove power (unplug) to the radio. Remove the bottom chassis cover of the radio.
Remove R113 and D68.
Connect a jumper wire between J14 pin +8V and J9 pin F1.
Clarifier/Frequency Counter Realignment:
It may be desirable to realign the clarifier position to better track with the frequency counter. Once the clarifier has been unlocked it will typically sit "on frequency" at about the 9 or 10 o'clock position. If this is undesirable, it may be reset so that the clarifier is at 12 o'clock.
1. Set radio to channel 20 (27.205).
2. Set clarifier on radio to 12 O'Clock position.
3. Remove the bias jumper board that connects TP7/TP8/TP9.
4. With the radio in AM receive mode, adjust L20 for reading of 27.205.
5. With the radio in USB receive mode, adjust L21 for reading of 27.205.
6. With the radio in LSB receive mode, adjust L22 for reading of 27.205.
7. With the radio in LSB transmit mode, adjust VR7 for reading of 27.205.
8. Replace the bias jumper board that connects TP7/TP8/TP9.
*Note: Adjusting step 6 should automatically adjust the same frequency in step 7 if the clarifier is unlocked. This won't replace a complete alignment, but it's pretty close.
(A good 6-digit external counter should be used in conjunction with the above procedure so that the external counter reads 27.2050, and the 959's built-in counter reads 27.205 with the clarifier at 12 o'clock).
~Thanks to Road Hog (Vinnie) RTDX422 for submitting this fix!~
A more precise calibration/alignment method has been shown to work better than the one above (which still works, but this one is recommended).
1. Set radio to channel 1 (AM mode).
2. Set clarifier on radio to 12 O'Clock position.
3. Connect frequency counter to TP3.
4. With the radio in AM receive mode, adjust L20 for reading of 16.27000MHz ±20Hz.
5. With the radio in USB receive mode, adjust L21 for reading of 16.27250MHz ±20Hz.
6. With the radio in LSB receive mode, adjust L22 for reading of 16.26750MHz ±20Hz.
“VR” Tuning & Alignment Components:
AM Power VR14
AMC (AM modulation) VR16
SSB ALC (Sideband mod) VR13
SSB APC (Sideband power) VR17
SSB Carrier Balance VR6
RF Meter Adj. VR9
S Meter Adj. (AM) VR1
S Meter Adj. (SSB) VR2
Squelch Threshold Adj. (AM) VR4
Squelch Threshold Adj. (SSB) VR3
Microphone Wiring Pinouts:
1-Shield & Blue
Yellow (not connected)
1-Shield & Red
Yellow (not connected)
Modification provides 73 "extra" channels:
49 above CB band, 23 below & 1 miscellaneous.
Total of 339 usable channels including sideband.
Low Band (23 channels) 69 incl. USB/LSB
CB Band (40 channels) 120 incl. USB/LSB
Miscellaneous (5 channels) 15 incl. USB/LSB
High Band (38 channels) 114 incl. USB/LSB
Super-High Band (11 channels) 33 incl. USB/LSB
CH P5 P6
CH P5 P6
CH P5 P6 26.695 5 Open Closed 27.135 15 Closed Closed 27.575 23 Open Open 26.705 6 Open Closed 27.155 16 Closed Closed 27.585 26 Open Open 26.715 7 Open Closed 27.165 17 Closed Closed 27.595 27 Open Open 26.735 8 Open Closed 27.175 18 Closed Closed 27.605 1 Closed Open 26.745 9 Open Closed 27.185 19 Closed Closed 27.615 2 Closed Open 26.755 10 Open Closed 27.205 20 Closed Closed 27.625 3 Closed Open 26.765 11 Open Closed 27.215 21 Closed Closed 27.635 31 Open Open 26.785 12 Open Closed 27.225 22 Closed Closed 27.645 4 Closed Open 26.795 13 Open Closed 27.235 24 Closed Closed 27.655 5 Closed Open 26.805 14 Open Closed 27.245 25 Closed Closed 27.665 6 Closed Open 26.815 15 Open Closed 27.255 23 Closed Closed 27.675 7 Closed Open 26.835 16 Open Closed 27.275 27 Closed Closed 27.695 8 Closed Open 26.845 17 Open Closed 27.285 28 Closed Closed 27.705 9 Closed Open 26.855 18 Open Closed 27.295 29 Closed Closed 27.715 10 Closed Open 26.865 19 Open Closed 27.305 30 Closed Closed 27.725 11 Closed Open 26.885 20 Open Closed 27.315 31 Closed Closed 27.745 12 Closed Open 26.895 21 Open Closed 27.325 32 Closed Closed 27.755 13 Closed Open 26.905 22 Open Closed 27.335 33 Closed Closed 27.765 14 Closed Open 26.915 24 Open Closed 27.345 34 Closed Closed 27.775 15 Closed Open 26.925 25 Open Closed 27.355 35 Closed Closed 27.795 16 Closed Open 26.935 23 Open Closed 27.365 36 Closed Closed 27.805 17 Closed Open 26.945 26 Open Closed 27.375 37 Closed Closed 27.815 18 Closed Open 26.955 27 Open Closed 27.385 38 Closed Closed 27.825 19 Closed Open 26.965 1 Closed Closed 27.395 39 Closed Closed 27.845 20 Closed Open 26.975 2 Closed Closed 27.405 40 Closed Closed 27.855 21 Closed Open 26.985 3 Closed Closed 27.425 12 Open Open 27.865 22 Closed Open 26.995 31 Open Closed 27.435 13 Open Open 27.875 24 Closed Open 27.005 4 Closed Closed 27.445 14 Open Open 27.885 25 Closed Open 27.015 5 Closed Closed 27.455 15 Open Open 27.895 23 Closed Open 27.025 6 Closed Closed 27.475 16 Open Open 27.905 26 Closed Open 27.035 7 Closed Closed 27.485 17 Open Open 27.915 27 Closed Open 27.055 8 Closed Closed 27.495 18 Open Open 27.925 28 Closed Open 27.065 9 Closed Closed 27.505 19 Open Open 27.935 29 Closed Open 27.075 10 Closed Closed 27.525 20 Open Open 27.945 30 Closed Open 27.085 11 Closed Closed 27.535 21 Open Open 27.955 31 Closed Open 27.105 12 Closed Closed 27.545 22 Open Open 27.965 32 Closed Open 27.115 13 Closed Closed 27.555 24 Open Open 27.125 14 Closed Closed 27.565 25 Open Open
The "A" channels:
CHANNEL FREQ. Mhz
CH P5 P6 10kc 3a 26.995 31
Closed Center 7a 27.045 7 Closed Closed Down 11a 27.095 12 Closed Closed Up 15a 27.145 15 Closed Closed Down 19a 27.195 20 Closed Closed Up
*You must use either enough clarifier "slide" or a 10kc switch to reach the "a" channels (except 3a). 27.255 is the only CB frequency shared with R/C