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)
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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
