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Superstar 3900 specifications, modifications. | Radioaficion Ham Radio

Superstar 3900 specifications, modifications.


Superstar 3900
Complete specifications, modifications.

Superstar 3900 Complete specifications, frequency chart, modifications.



Channels 40 CH
Frequency Range 28.065 to 28.505 MHz
Frequency Control Phase Lock Loop (PLL) synthesizer
Frequency Tolerance 0.005%
Frequency Stability 0.001%
Operating Temperature Range -30 C to +50 C
Microphone Plug-in dynamic; with push-to-talk switch and coiled cord
Input Voltage 13.8V DC nominal 15.9V max. 11.7V min. (positive or negative ground)
Transmit: AM full mod. 2.2A. SSB 12 watts PEP output 2A.
Receiver: Squelched 0.3A. Maximum audio output 0.7A.
Size 2 3/8" (H) x 7 7/8" (W) x 9 1/4" (D).
Weight 5 lbs.
Antenna Connector UHF SO239.
Meter (3-in-1) Illuminated; indicates relative output power received signal strength and SWR.
Main Board EPT360014b


Power Output AM/FM/CW, 5 watts SSB, 12 watts, PEP
Modulation High-and-low-level Class B, Amplitude Modulation: AM. Variable capacitance Frequency Modulation: FM.
Intermodulation Distortion SSB: 3rd order, more than -25 dB. 5th order, more than -35 dB.
SSB Carrier Suppression 55 dB
Unwanted Sideband 50 dB
Frequency Response AM and FM: 450 to 2500 Hz.
Output Impedance 50 ohms, unbalanced.
Output Indicators Meter shows relative RF output power and SWR. Transmit LED glows red when transmitter is in operation.


Sensitivity SSB/CW: 0.25 uV for 10 dB (S+N)/N at greater than 1/2 watt of audio output. AM: 0.5 uV for 10 dB (S+N)/N at greater than 1/2 watt of audio output. FM: 1.0 uV for 20 dB (S+N)/N at greater than 1/2 watt of audio output.
Selectivity AM/FM: 6 dB @3 KHz, 50 dB @9 KHz. SSB/CW: 6 dB @2.1 KHZ, 60 dB @3.3 KHz.
Image Rejection More than 65 dB.
IF Frequency AM/FM: 10.695 1st IF, 455 KHz 2nd IF SSB/CW: 10.695 MHz.
Adjacent-Channel Rejection 60 dB AM/FM & 70 dB SSB/CW.
RF Gain Control 45 dB adjustable for optimum signal reception.
Automatic Gain Control (AGC) Less than 10 dB change in audio output for inputs from 10 to 100,000 microvolts
Squelch Adjustable; threshold less than 0.5 uV.
ANL Switchable.
Noise Blanker RF type, effective on AM/FM and SSB/CW.
Clarifier Range Coarse (TX/RX) + or - 7 KHz. Fine (RX) + or - 1 KHz.
Audio Output Power 4 watts into 8 ohms.
Frequency Response 300 to 2800 Hz.
Built-in Speaker 8 ohms, round.
External Speaker(Not Supplied) 8 ohms; disables internal speaker when connected.

Channel Modification
On the solder side of the board near the front locate 4 resistors soldered in a spider / criss-cross pattern.
Desolder these resistors. Be sure not to bridge the connections while removing these resistors. When done, be sure that all connections the resistors were removed from are soldered well.
You should now have 26.965 - 27.405 in High Band D.

Roger Beep Disable / Switch
Cut J9 Jumper (located on the board behind the meter assembly) and leave it open making sure the legs are not touching anything. This will disable the Roger Beep. You can also run a wire from each end of the jumper through a switch, so you can make the roger beep switchable, on and off.

Power Tweaks
Replace R174 (10k resistor) with a 1K resistor.
Replace R187 (10k resistor) with a 1K resistor.
Mod Limiter - R249 (removal NOT recommended)
Modulation - VR14 (Set for just under max)
AM Power - VR13 (Set for 4-6 watts deadkey)
SSB Power - VR12 (Set for max)

Clarifier Track on Transmit and Receive
NOTE: This mod is NOT recommended unless a frequency counter will be used.
1. Find the green wire located at point 54 and desolder 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 pot and desolder it. Tape or shrink tube the cut end. This wire will not be used.
4. Find D75 and lift one end.
5. Find R135 (33k resistor) and lift one end.

+ 10 kHz Jump Switch
1. Mount a SPST switch in a convenient location on the radio.
2. Locate J68 and J69 in front of the board the channel selector switch is mounted on.
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.

superstar 3900 + 10 kHz Jump Switch

Additional 10 Meter Frequencies
1. Locate pins #12 and #13 on IC7 (MC14008BCP chip).
2. Using a SPST toggle switch, wire as follows:
3. Wire the center pin of the toggle switch to pin 13
4. Wire the bottom pin of the toggle switch to pin 12
The new channels will work with the band selector on band D when the switch is thrown. Frequency range is 28.300 - 28.500 MHz, allowing you to recover lost frequencies after the 11 meter modification.

superstar 3900 Additional 10 Meter Frequencies

Mic Wiring
(1) Shield / Ground
(2) Modulation
(3) Transmit
(4) Receive

I had some doubts when I first heard I was given the opportunity to review the Superstar 3900 (SS3900). I mean, a SSB radio for a little over a $100 with "extras"? So I hooked it up and went to work. The 11-meter mod was a cinch. Desolder four resistors and you're done. It takes longer to take off the cover and put it back on than it takes to do the freq mod. Just be sure if and when you do it, you don't bridge any of the gaps with solder and you'll be fine. Get a good soldering iron, if you don't have one already, preferably one that's grounded if you plan on doing any internal work. Forget about a soldering gun unless you want problems. The tip is too big and it gets way too hot. Anyway now that I have given you the tip for the day, back to the review.

The SS3900 is made in Malaysia and built on your typical DX chassis, with the black covers and the chrome face. From a distance it resembles the famous Cobra 148GTL, and all in all the radio is very comparable to that old favorite in many ways. The SS3900 features a single 2SC1969 final transistor, which allows for an easy 18 watts on SSB with no fancy mods to get there. I set mine up with an AM carrier of 3 watts and allowed the ample modulation this radio generates to carry the weight. Modulation is no problem, and even with the stock mic, your maximum SSB PEP outputs are easily attainable. I was actually impressed by the stock mic. Not only by the clarity and punch it had, but I liked the feel of it. Most export mics are skinny and blah. I liked the stock mic, it feels authoritative. I am not one that likes to hack a radio to hell and back for 4 or 5 extra watts. What’s the point? So I left the SS3900 stock and it performs very well.

On the face you will see the standard meter which is of the small kind, unlike the new larger, easier to read Galaxy meters, but nonetheless it's one we are no doubt all familiar with. The meter has a S meter scale, along with and SWR scale and the SWR calibration set point. Next you will see the switch for the meter. The switch controls the displays on the meter from Signal, to SWR calibrate, to SWR read. Simple and straightforward to use. Next we come to the NB/ANL /OFF switch which of course allows you to switch the noise blanker circuit on and off. The next switch in the row is the bands switch which, depending on where you want to operate lets you select between HI and LOW band. The last switch on the upper most part of the face of the radio is the Channel 9 selector. Flip the switch and you are instantly on the "Emergency" channel that no one monitors anymore anyway. Of course you could always use this switch for other modifications, but I chose to leave it intact and affix my own switches for the other options. More on those later. Last but not least we come to the TX/RX LED which when you are transmitting, lights up red, and when receiving stays green, and the green channel display, a standard 1-40 readout.

Continuing on the face of the radio you will find a dual concentric control for the volume (ON/OFF) and the squelch. Next you come to another dual concentric control for the RF gain and the Mic gain. The third knob allows you to calibrate the meter from the measurement of SWR. Next is the band selector switch, which allows you to choose any of the six bands of 40 channels this radio is capable of. This is where the HI/LOW band switch I mentioned before comes in. With the band selector switch on "LOW" you can access bands A-C, and with the band selector switch on "HI" you can access bands D-F. (See the channel roadmap for channel assignments and the frequencies). The last knob on the farthest right side of the face is another dual concentric that controls the fine and coarse clarifier adjustment. The inner concentric is the fine adjustment and the outer concentric is for coarse adjustment. I have included a mod with this review explaining how to "unlock" the clarifier allowing it to track on transmit as well as receive. This is a fine mod, except without a frequency counter you won't know exactly where you are at with regards to transmit frequency. Given the fact that radios with these boards tend to be unstable frequency wise, especially on sideband, a freq counter is a necessity if you decide to unlock the clarifier control.

The standard 4-pin mic connector is located on the right side of the radio (looking at it from the front) and accepts microphones wired for any 4-pin Galaxy radio.

On the rear of the radio's chassis you will find, of course a SO-239 antenna connector, as well as the power connection. This radio also has an extension speaker jack, and a jack for your CW key. I would like to give credit to the engineer who had the foresight to pre-wire the jack for the Galaxy III Frequency Counter (sold separately), which is also on the back. Simply plug the counter in and you're ready to go. A nice touch since this radio lacks a built in counter like many of its close counterparts.

Well that's the full description of the radio as it comes stock. I have added a few minor upgrades, which I will discuss next. What I can't understand is why someone would design a radio with a roger beep you can't turn off! The first thing I did was to attach a switch to the rear of the radio to turn the thing off. This is where the Channel 9 switch can come in handy. If you don't want to mount another switch you can use it to turn the roger beep on and off. It's a simple mod that requires cutting a jumper (J9) and then running a wire from each side of the cut jumper to separate legs on a SPST toggle. I ran the wire from the jumper to the switch along the existing wire cluster inside the radio and wiretied it fast. It looks neat, and should be problem free.

Next to the roger beep switch on the back panel I mounted another toggle for the 10 kHz switch. Another mod, slightly more difficult than the roger beep switch, only because getting to the jumpers you need (J68 and J69) to wire the switch off of is a pain. The mod itself is simple, just run a wire from J68 to one leg of a SPST and another wire from J69 to the other leg of the switch, it's just getting to those jumpers that's difficult.

I mounted both of the switches on the rear mainly because I didn't want to drill holes in the covers of the radio. You can't mount them wherever you please as long as they will not interfere with the internals of the radio or the mounting bracket. I chose to put my two switches right between the final and driver transistors. When you drill holes in the metal chassis, regardless of where you are doing it, be sure to get ALL OF THE METAL SHAVINGS OUT OF THE INSIDE OF THE RADIO! Having stray pieces of metal lying around on the board may cause catastrophic failure. Better yet, drill the hole with the radio upside down and they'll fall out on your workbench, not inside the radio.

I did not do the clarifier mod because, number one I never would use it, and secondly without a frequency counter (which I don't plan on buying just for this radio) I can't tell where I am at anyway. It seems simple enough though, as I explained previously. If you are looking for 8 VDC and you do not want to solder to the transistor leg like the mod requires, there is an 8VDC source on the small board to the rear of the channel display. It's easy to get to and allows you to run your wires up and out of the way for a clean, neat job.

I also did not do the extra 10 meter frequency mod, because I have no need for that modification either. Plus it requires adding yet another switch to toggle between the CB channels and the 10 meter frequencies that were lost after doing the 11 meter mod.

Like I said before, I am not one to hack a radio just for the sake of a few extra watts. I set my AM carrier at 3 watts and allow the radio to peak out at about 15 or so watts. SSB is just as good with a PEP of close to 18 watts. I am happy with and you should be too. Want more power, buy a dual final radio. I set the modulation to just under 100% and the radio performs well with a stock mic at this setting. Put a power mic on the SS3900 and she'll really scream! All in all the way I have the radio tuned will allow the radio to perform cleanly and without excess strain on any of the components.

There are a few PROS and CONS, which I will illustrate below. You can weigh their merits based on your own wants and needs in a radio.

Simple, and easy to use, straight forward,operation. No freq counter.
All-mode operation (AM,FM,USB,LSB,CW). No roger beep ON/OFF switch.
Classic design. No 10 kHz switch.
Ease of ability to upgrade. Small meter.
Freq counter plug on back. Poor frequency stability on SSB.
Good stock microphone. AM and FM receive sensitivity could be better.
Excellent receive audio.
Snappy transmitter power.
Excellent voice quality on transmit.
Best CB value for the dollar, hands down.
Familiar board design.

So after all this, do I like the radio? Yes I do. I personally think the Superstar 3900 is the best bang for the buck going in CB radios. It lacks a lot of the bells and whistles of some of the Galaxy radios but most of those features can be added on the cheap, and you will still come out ahead financially over most radios in the Galaxy line. I was especially impressed by how other operators told me how good and clean the radio sounded, and by the clarity and punch of the receive audio. If there is one thing I would ask the manufacturers and designers of this radio, is that they should fix the SSB drift. You know they don't make the good old Cobra 148GTL anymore, and with a few minor tweaks this radio could easily replace it. Clean up the sloppy sideband drift, put in a roger beep switch (perhaps in place of the Channel 9 switch?), and this radio with its classic design could be the replacement for the 148GTL without a doubt. Overall this is great radio value for the dollar and I would recommend it to anyone in the market for a radio in its league.

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