Equipment

Superstar 3900

Superstar SS3900The Superstar 3900 is the modern version of the “old” classic Cobra 148 GTL-DX, also known as the Superstar 360FM. So what’s it like, the good, the bad revealed…

I bought a SS3900 brand new after reading quite a positive review on these radios. Obviously, I’m not expecting the same performance from it that I get from my Kenwood, Icom and Yaesu’s. But how do I rate it? Read on…

Overview

Upon removing the radio from the packaging, it appears remarkably similar to the good old Cobra 148/Superstar 360 from the early 80’s. The case is finished in the same crinkle black finish, the obligatory chrome fascia now has a small step to highlight the front panel.

Superstar SS3900 with Superstar 360FMHere we see the new SS3900 compared to an original SS360FM (bottom) It’s hard to believe this Superstar 360FM, once owned by me many years ago, has been in my friends cupboard, untouched for at least 15 years.

The layout of the front panel is the same, although for some obscure reason, the band selector is labelled as “Dimmer”. This control is marked up for the six bands in lots of two, i.e. for bands A/D, B/E & C/F.

The two sets of bands are selected from the “Tone” switch, “Low” selecting bands A-C, “High” selecting bands D-F.
The knobs are now no longer round, but a squashed hexagonal shape, which now almost matches the original channel change selector knob.

Turning to the back of the radio, it sports the same power, extension speaker and CW key sockets. Now added is a connector for a dedicated frequency counter. The serial number is no longer stamped into a nice little aluminium plate riveted to the back, it is now just a paper-based sticker.

Internally, the new PCB has a very familiar look and layout, with only a few minor changes. Gone are the hard wired connections to the PCB with connector plug and socket arrangements now being employed for most cabling connections.

Comparing the schematics & PCB’s from this radio and the original radio reveals almost identical circuits, apart from different RF finals, the component numbering being the only real difference.

Overall, visually externally, very similar and only someone who knows the original 148/360 would instantly spot the differences without any being pointed out.

In Use

Powering up the radio we have the familiar red LED 1-40 channel numbers and the S/RF meter lit by an incandescent lamp – not a harsh white LED. As we can already see in the image above, it looks very similar to the original radios.

The six bands now cover a frequency range from 25.615MHz on channel 1, band A; to 28.305MHz on channel 40, band F, whereas the original unmodified Cobra 148/ Superstar 360 covered 26.515MHz to 27.855MHz.

The first test was to check it using a frequency counter, note the matching frequency counter which plugs into the back of the SS3900 was NOT used for this measurement.

How did it do?
Well, AM/FM was off by nearly 100Hz, turning to SSB, again both USB and LSB were also off frequency, with LSB being the worse of the two. Overall, it wasn’t much in the grand scheme of things, but for a brand new radio straight out the box, I really would expect it to be a bit closer!

Anyone who knows the circuit inside, will appreciate that AM/FM, USB and LSB each have their own adjustment coils in the VCO circuits.

Next comes the audio transmission, which is good, clear and up to scratch, apart from FM where it tends to be a bit on the quiet side. I found myself having to talk rather loudly into the microphone, with it almost touching my mouth, a simple modification cures this problem.

A word of caution, if you intend to use any amplified microphone, you could end up overdriving the radio.

The transmission has the uniquely identifiable roger beep, although it sounds very similar to the original, and the beep circuit is identical in every way, it’s just very slightly different to the original, but can be very annoying to people listening.

A simple snip of jumper J9 on the PCB disables the beep, while a switch can put in place of the jumper to make it switchable if desired.

Another desirable mod is to add a +10KHz switch, this allows the use of the “black holes” or “Alpha” channels. These were originally five channels where the frequency jumps by 20KHz (or 2 channels) as standard.

Now the bad news: until the radio has been switched on for a while, maybe 15-20 minutes or longer, the frequency drifts all over the place until it finally settles down. So, turn it on, go have a cup of coffee, read the paper and then come back to the radio…

It has been suggested on various forums that it is the connection for the external frequency counter which accounts for some of the VCO drift. As a test, I removed the connector from the PCB and it made no noticeable difference, likewise, it didn’t make any difference with or without the external counter connected.

The signal meter has inherited it’s laziness from it’s predecessor and hardly registers signals below S7-8 – again a quick fix by replacing a 1N4148 . Once replaced, the germanium diode has a lower forward voltage drop and makes the meter circuit more sensitive.

The signal meter presets VR1 (AM/FM) and VR2 (SSB) will need to be adjusted to reflect the increased sensitivity of the metering circuit.

RF output power was slightly down on spec, being set at just over 3 Watts on AM/FM, although it produced a reasonable 10 Watts on SSB. A quick adjustment brought the power up to 4.5 Watts, although it is possible to raise the level further, I don’t want to destroy the MOSFET output transistors.

Build quality

This is the biggie! It’s nowhere near as good quality as the old 148’s, the PCB in my one was not sitting in the chassis guide along one side of the radio, and was being held flexed under tension by the legs of the 8v regulator. Soldering is good, with evenly flowed joints and no dry joints being observed.

Superstar SS3900 PCBInternal view of the SS3900 – the upside-down 8v regulator bolted to the chassis next to the mic socket was added by me to power my desk mic. After this picture was taken I also installed an EPROM board to give me the UK 27/81 channels instead of the standard band A.

EPROM boards for the SS3900 are available from Spectrum Communications, I have absolutely no connection with Spectrum except as a happy customer since the mid 80’s

Wiring is tidy and kept in place by cable ties. I do have to mention that upon installing the EPROM board, I found a few wires needed re-soldering to the front controls – one simply fell off the band switch, upon close inspection it had been hanging on by just a single strand of wire!!

Near the front of the PCB there are two wiring connectors that sit side by side, these connectors are so close on the PCB that the plugs cannot be seated squarely as one is forced against the other.

The speaker wires on this chassis are now also on a plug which, in theory, means you no longer have to de-solder them from the speaker to remove the bottom casing.

However, on my radio, this plug has been secured in place with some substance, and refused to separate, necessitating in de-soldering the speaker cables.

Mounted on ceramic insulators are the RF MOSFET final transistors. It appears the heat transfer paste had been liberally applied to these transistors by the local plasterer. There really is no need to spread it all around the rear chassis and the front of the transistors where it’s not required.

The SWR measuring board has not been mounted squarely, and is sitting at an angle, fortunately, the solder joints are still made effectively.

Next we have what appears to be an additional RF low pass filter on the antenna socket. It’s a small aluminium box through which passes the antenna wire. Presumably, this was put in place to satisfy the spectral emissions regulations for certain countries.

Is it neatly done? Errr, no! It looks like it’s been thrown in as an afterthought and has been soldered precariously to a tag on the SO239 socket.

Finally, we come to the clarifier control. The coarse control has enough range to shift the frequency down by approx. 4KHz, however, it can shift the frequency up by 7KHz. I have to say, it would be preferable to have an equal amount of shift in both directions.

The $64,000 question

Would I buy another one?
Maybe! As a cheap CB it’s OK, but that’s all it is, just OK. This version is most certainly not ever going to become a sought-after classic. On a positive note, with a few mods and a quick alignment it does well for a budget radio.

If being a few KHz off-frequency doesn’t bother you (it should) or you don’t mind getting it checked out from new, or you simply want a CB with the classic 80’s look then it’s fine.

Placed alongside an original Uniden Cobra 148/Superstar 360FM the old radios win hands down, and that’s probably the reason the originals are more expensive to buy today than these Malaysian boxes.

*UPDATE* Yes, I have indeed bought another one, it’s an older CRT SS3900. This was sold as “spares or repairs” – I had it on the bench for a short while and it’s taken the place of the Ranger SS3900!

The Ranger is now nicely packed away in it’s box, maybe it will come back out one day.

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