10 September 2016

Superstar 3900 EU - Complete Technical Analysis

As you will be aware there has been a lot of talk recently about the UK launch of the Superstar 3900EU. Below you can read a full technical report about the radio as provided by Superstar UK:

(Click images to enlarge)

****************************************

Superstar 3900 EU - Complete Technical Analysis


"This is a very stable and very well built radio. Congratulations to Ranger on this radio. I can't fault it."



Superstar UK asked Steve Gibbs of Gisco UK to take a Superstar 3900 EU and give us his analysis. Steve Gibbs is one of the UK's most well known radio engineers in the UK. Steve has serviced and aligned tens of thousands of radios over the last 30+ years and is highly respected in this sector. 




Whilst Superstar UK have great faith in the Superstar 3900, Superstar UK wanted to have it independently and impartially analysed. So we asked Steve Gibbs to take a look at a factory-sealed Superstar 3900 EU. Steve is well known for telling it how it is with a no-nonsense approach. Here's Steve's analysis of the Ranger-built Superstar 3900 EU.



Steve's first comments were on initially opening the box were presentation. Steve was particularly impressed that Ranger had taken the time to place a protective film over the black power-coated back casing.


​After unwrapping the radio, Steve commented on the outer build quality. Unlike some earlier 3900s he'd seen in the past, which had felt a little flimsy; this one felt like a quality bit of kit. Steve initially tested the knobs on the front commenting on how precise they felt with absolutely no wobble or excess play "very nice" he said. Steve added that the front knob shafts are rock solid, with no reduction in spring pressure when the volume control on/off switch is used.


Then Steve moved on to the channel select commenting that its "probably the most used switch on a radio such as this". He commented that it felt very precise and well put together, and that some cheaper products' channel select can feel flimsy, this one felt solid - you can feel a definite clunk when a channel is changed ensuring a solid connection.

From left to right is Volume Control (inner) & Squelch (outer), Mic Gain (inner) & RF Gain (outer), SWR Calibrate, Dimmer (or band select in export mode), mode select, Clarifier Course control (outer knob) Clarifier Fine control (inner knob).



​Aesthetics aside, Steve's passion is for the electronics! So Steve naturally moved on to open the unit. Steve's first comment was on the tidiness of the board, and wiring. All engineers like a tidy board, as it makes for easy servicing.



From a service point of view, some radios such as this have the speaker cable soldered to the main board which means the first thing you have to do unsolder the speaker cables. Not with this radio, the speaker connector is conveniently connected using a simple PCB plug and socket.


Speaker and bottom casing out of the way Steve again commented on the channel change mechanism from inside, commenting that it looks very good quality and unlike cheaper channel changes he doesn't envisage any issues to develop with this one.

Moving on, Steve removed the top case to take a look at the solder work. Here's a look at the solder side of the PCB. Steve comments included very tidy; no scorch marks and very neat.

Fig. 1: Superstar 3900 Right Side of the Board - Voltage Regulator, Mic Preamps etc.

​Fig. 2: Superstar 3900 Left Side of the Board - Output stages, VCO & Crystals etc.

Now that Steve was satisfied with the solder work, he moved on to inspect the component quality. Starting from the output stage he worked his way along the board.


It's important to note that the Superstar 3900 Steve had on his bench was a randomly selected radio from the first batch sent from Ranger. Steve did not adjust or realign the radio. This is Steve's analysis directly out of the box.

​Fig. 3: Superstar 3900 Output Stage View

The output stage of the Superstar 3900 is made up of a single IRF520. Straight out of the box on FM the radio did 4.0W on FM/AM and ~ 12W SSB.


Steve added that this radio would be capable of up to around 50W by using an uprated mosfet. As can be seen on the top-left side of fig 5.1.

​Fig. 5.1: IRF520 Mosfet & Gate Voltage Circuitry Close Up

Next up is the front middle section. Steve's first comment is that sometimes manufacturers try to make micro cost savings by using the cheapest components resulting in a component mismatch. Ranger, here, have used all the same brand and type capacitors. This is great for build quality, but also for easy service. Thumbs up to Ranger here!

Along the left hand side, from left to right here we have TX adjust, RX adjust, NB/ANL adjust. The two pots in the middle are for SSB, then there are three smaller pots below which is the location of the FM discriminator. Steve's comments are that all adjustment pots are exactly where you'd expect them to be and meet or exceed expected component quality.

​Fig. 6.1: Front Middle Section - Radio Adjustment

Superstar 3900 is a PLL controlled radio with two 4008 binary adders. Here you can see a close up of the VCO.

​Fig. 6.2: VCO & Phase Locked Loop

​Looking closer, we can see the reference crystal, and offset crystal, alongside their adjustment pots. Directly beneath the crystal to the right of Fig. 9 we can see the export jumper (more about that later). Again Steve comments that these pots are of expected quality.


​Fig. 9: Reference Crystal & Offset Crystal

Looking at Fig. 10, we can see that Superstar 3900 is fitted with a ferrite coil. This is essential when using a radio in a vehicle as it helps to dampen the engine noise and reduce it coming through the radio.


There's also a diode across the power terminals. This will ensure that if you power the radio with incorrect polarity, that the fuse in the power will be blown before the radio suffers any damage. This is a really good reason to ensure that the correct power cable is used with the correct current rating of fuse.


​Fig. 10: - Input Voltage Regulator etc.​

​Steve was then keen to get the radio powered up and on to his fully calibrated set of instruments. Again, it's important to point out that Steve was asked not to align this radio and not to adjust it, in any way. Superstar UK wanted an out the box analysis that accurately reflects the radio a buyer should expect to receive.

The following analysis was done immediately out of the box whilst the radio was cold. Steve was asked to give Superstar UK a screen-shot of the instruments as they changed, noting the length of time the radio had been switched on, and monitor the radio as the it warmed up.

Steve continually monitored and used radio for 90 minutes whilst attached to his calibrated set of instruments. To Steve's surprise the radio was smack on frequency immediately on switch on, and nothing changed as the radio warmed up. Here's the screen-shots Steve gave - here's the moment of truth.

The first thing Steve wanted to measure is the FM reference frequency. This should show 16.4900MHz - and it does.

​Fig. 12: FM Reference Frequency Analysis - 16.4900MHz

Next, the USB reference frequency, spot on at 16.4925MHz

​Fig. 13: USB Reference Frequency Analysis - 16.4925MHz

Next, the LSB reference frequency analysis, again spot on at 16.4875MHz


​Fig 14: LSB Reference Frequency Analysis - 16.4875MHz

Next, the LSB offset frequency analysis, spot on at 10.6975MHz

​Fig. 15: LSB Offset Frequency Analysis - 10.6975MHz

Finally, the USB offset frequency analysis, spot on at 10.6925MHz

​Fig. 16: USB Offset Frequency Analysis - 10.6925MHz

​The transmit. And the result? Right out of the box on FM is 27.185001MHz and smack on 4.0W.

​​Fig. 18: Transmit Test

​Receive Test. ​The receive parameter standard set in the manual supplied says 1.0uV at 20dB. Steve does his test at 0.821uV and 21dB, which exceeds the manufacturer's recommendations. Here's the result. Smack on at 27.18500MHz.


​Fig. 17:​ Receive Test - 27.18500MHz

Steve had the Superstar 3900 EU on his fully calibrated instruments for over 90 minutes, re-analysing all of the above with virtually no change. Steve added, "This is a very stable and very well built radio. Congratulations to Ranger on this radio. I can't fault it.".

So there we have it. A glowing analysis from one of the industry's most well respected and trusted radio engineers. Steve pulls no punches and tells it how it is.

The most observant will have noticed that the Superstar 3900 EU is the same Superstar 3900 which has been for sale in the EU marketplace for some time now. When it was agreed that the Superstar 3900 was to be brought into the UK, a decision was taken to call it Superstar 3900 EU to differentiate it from any previous model of Superstar 3900. Superstar 3900 EU is locked to mid-block CEPT EU channels at 4.0W making it legal for sale in all EU countries. It was important that this 3900 was not confused with any previous versions that might have been 10m amateur radios.

The Superstar 3900 [EU] is ROHS compliant and CE approved. The ROHS/CE certificate is available to anyone by simply emailing sales@wearesuperstar.co.uk


Superstar 3900 has been manufactured by many factories in China over the last two decades. There have been many versions which may have been of a reduced quality and have suffered from "frequency drifting". It was important to Superstar UK that this version of the Superstar 3900 was easy to differentiate from those older models.



There has been much speculation that this version of the Superstar 3900 may suffer from the same frequency drifting issue as previously Chinese manufactured versions. Superstar UK contacted Ranger about this issue. Ranger were confused as they had never had this queried on their product before. They responded with "[There is] no drifting frequency problem for our product.".



Superstar UK are very excited to bring the Superstar 3900 back into the UK market place. And with Gisco's analysis, buyers can be confident in their purchase. As we can see from the analysis by Steve, the current Superstar 3900 is stable and a beautiful, rock solid AM/FM/SSB radio.


​Superstar 3900EU is available at most major UK CB/ham radio retailers from Monday 12th September 2016.

For more information, please see www.wearesuperstar.co.uk or see the Superstar UK facebook page.



****************************

This report was kindly sent for publication on the blog from Superstar UK and has been published in full. From a personal point of view I'd like to thank all those involved and say 'top marks' to Superstar for taking the time to publish this report. Afterall, when was the last time you seen a report like this from other radio manufacturers????

****************************