Performance Test Of The DX 2547
This is the first base station in the line of Galaxy CB radios. In
these days of converted 10-meter radios, companies like Cobra, Midland and
Uniden seem to be trimming their CB radio lines. Cobra with the
elimination of their base station radios. Midland back in the hay days was
one of the first manufacturers with a line of true single sideband radios
now with only one mobile in their SSB lineup. Uniden earlier dropped the
PC122, a low cost AM/SSB mobile. More recently they have eliminated the
rest of the SSB line with the removal of the Grant mobile and the
Washington base. The only other SSB brand with an AM/SSB base station CB
radio is Texas Ranger. Cherokee has a base radios on their web site, but they
aren’t to be found in the real world.
With all the manufacturers moving away from base station and SSB CB
radios, it was a surprise to me when I learned of the new Galaxy DX 2547
CB base radio. It sure made me wonder what might be so special about this
radio that would make sell in the current marketplace. Will it be the
replacement for the Uniden Washington or the Cobra 2000 GTL? Or is it
somewhere in between? These are the reasons for picking this radio as
cover story of the first web edition of CB World Informer.
The radio is made for Galaxy, to Galaxy specifications by RCI. The
photos on the Galaxy site and the photos on the box, although very
professionally done, don’t do the radio justice. I wasn’t able to
capture the true appearance of the radio face with my camera either. I
tried many lighting sources and camera settings. The radio just looks so
much better in person. A customer came into the store and said “I saw
the new Galaxy base on the web, I wasn’t impressed.” I then showed
them the radio and they immediately said “I like that, it’s a nice
looking radio.” I’ll do my best to describe the face of the radio. The
face color is a metallic platinum color with charcoal gray accents and
knobs. The indicator area is black giving a high contrast for the LED and
meter display. The face has black lettering on the platinum background
while there is white lettering on the charcoal and black backgrounds. It
is much more impressive to view the real radio.
may be very important, but the performance and functionality is paramount.
The DX 2547 has all the features of the past top of the line CB base
radios of the recent past and then some. Little things like front legs
that flip down tilting the radio for better viewing don’t add to the
cost of the radio but make a difference in making it user friendly.
Sometimes it’s simple well thought out features like this that make a
radio stand out from the competition.
is a picture of the radio with all the listed control and indicator
functions so you can familiarize your self with the radio. Click on
picture for close-up view.
are a list of controls and indicators with comments about each of
power switch. allows the radio to be turned on and off without
disturbing the volume setting. Also reduces wear on the volume
control and panel around the volume knob for those who rub the front
panel while turning the knobs,
4 function meter is easy to see and reads up to 60dB on the S-meter
scale. It reads modulation in the AM mode as well as all mode power output
and SWR with auto calibration, but is most accurate at full power.
All functions were very accurate for an internal meter. Some
operators will be disappointed that there is only one meter, but
accuracy is more important than quantity.
is a standard easy to read red LED 40 channel display selected
directly by the channel selector switch.
DIGIT FREQUENCY COUNTER
update constant readout 6 digit frequency counter reads down to
100Hz. It is quite accurate, although the last digit sometimes seems
lazy by change a little slowly while changing the clarifier
position. When adjusting the frequency to 27.4051 then
slightly move the clarifier just until it reads 27.4050 then turn the mode
switch to another mode and back again then it might read 27.4049.
This isn't a major concern, just an observation. This also happens
in the other RCI products using this frequency counter board.
BACK VOLUME CONTROL
talkback volume control also has an off switch position. Talk back
works in AM and SSB with plenty of clear volume and minimal RF
is the typical 1/4" headphone jack. Not a heavily used option,
but some operators wouldn't be without it. Also a good position for
an additional switch.
PIN MIC CONNECTOR
4-pin microphone connector. Wired the same as all the Galaxy radios.
Cobra/Uniden 4-pin mics will work on this radio. Also the mic jack
will supply power to the RCI SRA-117 echo mic.
feature only found on Galaxy CB radios. And one that in the past the
FCC wouldn't approve in a type accepted radio. It works in both
AM and SSB giving the radio a very flexible range.
the gain from off to full with very gradual and even control. Very
useful when using an amplified mic like a D104 where the gain
control is on the bottom of the mic. Gain adjustments can be made at
receiver gain control and very low distortion at low gain settings.
Reduces a S-9 signal to S-0 and a 30dB signal to S-9. Works very
the desired meter reading you wish to display. The SWR meter automatically
calibrates as you transmit.
all the LED displays and meter light to your desired brightness.
the receiver audio tone. Can be used to clean up hard to understand
transmissions by turning it clockwise increasing the high frequency
response. Or it can reduce the amplitude of noise spikes by turning
the control counter-clockwise decreasing the high frequency response
and increasing the low frequency response. It has a very good range.
the roger beep on and off. The roger beep is not over powering and
very short in duration. Galaxy seems to have tried to appease the many
that have been annoyed by the piercing elongated beeps of the past.
Address On/Off switch.
real channel selector switch, not a rotary Up/Down encoder. When the
radio is set to a channel it stays there, unlike some of the newer radios
that if the memory supply is interrupted they revert to channel 9.
Upper Sideband, AM or Lower Sideband with this switch. My personal
preference is LSB/AM/USB instead of the USB/AM/LSB order of
selection on this radio.
NOISE LIMITER SWITCH
is used to reduce noise in the AM mode. It seems the ANL is on all
the time when the NB (noise blanker) is off. With the NB on there is
a definite deference when the ANL is switched on and off. Checking
the schematic, it doesn't appear to be the intended operation of
noise in both AM and SSB. Works by reducing or removing noise spikes
at the first IF. The noise blanker in this radio is very effective,
one of the best I've used.
NOISE FILTER SWITCH
the high frequency response reducing the amplitude of noise spikes.
There is no documentation on this circuit in the Service Manual. I
can only guess that it's a active audio Bandpass filter with a
cutoff point somewhere around 1Khz.
the clarifier out of the circuit. Puts the receiver on center slot.
Also comes in handy once the clarifier is unlocked.
the receiver frequency ±.1Khz.
the volume to a suitable level. Works well with plenty of volume.
the threshold for squelching deferent signal levels.
SWITCH TO CHANNEL 9 OR 19
access to channel 9 or 19 no mater which channel your channel
selector is set to.
actually adjustable, but folded under, the radio sits flat for
placement on higher levels like on a shelf. Flipped down the radio is angled
upward for easier viewing on lower level locations like a desk or
Now for the performance test of the DX 2547. First, this radio came
from a distributor and no one Knew this was going to be tested and reviewed
by CB World Informer. There is no reason to expect any radio to perform
differently from this on tested, although this one has a quirk in the ANL
function which is covered above. I've submitted and E-mail to Galaxy tech
support about this and will add their response as soon as it's received.
returned my E-mail and confirmed the problem by checking some older and
newer DX 2547 radios. The problem is that the J6 connector on the main
circuit board is reverse on my radio and others at their site. It's
unclear how many radios are involved, but the solution is simple. Unsolder
the three pin J6 connector from the main circuit board then rotate it 180
degrees and re-solder it.
Checking the frequency stability from cold to warm, I found it took
about 15 minutes for the radio to warm up and it settled down close to
center slot after changing about 250Hz . This may vary from radio to
radio, but I would expect it to be close. The frequency from the factory
was within 100Hz of center slot and the counter alignment was on the
far as transmitter performance, both AM and SSB audio are very high
quality. The stock mic is adequate, but it sounded better with an EC-2018
turbo echo mic from RF Limited with or without echo. It will sound great
with an Astatic amplified mic, especially a D104 type base mic. Out of the
box the AM
modulation peaks around 50% and the power readings are listed below.
||Power Control Down
||Power Control Up
TX Dead Key
Testing the receiver with the signal generator, the radio seemed to
meet the specifications. It performed as well as or better than most
radios on the market. The sensitivity is very good and adjacent channel
rejection is also impressive. But the true test is on the air with peaked
and over modulated radios in close proximity. Being located in the middle
of a wholesale produce market, there are hundreds of over the road drivers
running power delivering in the area and in the building that my shop is
located in. This is one of the best test beds for receiver performance.
With the radio connected to a Solarcon I-Max 2000, I scanned around
listening for familiar voices. After monitoring AM for a couple of
hours, I found the receiver to be quite sensitive and exceptionally clear.
With the tone control set at mid-way the audio frequency response was the
best I've heard from solid state equipment. Transmissions from the regular
operators I'm used to hearing sounded fuller with just enough bass
The sideband receiver was equally clear. The radio has a natural sound
on sideband that's easy to listen to. Tuning into a station is easy with
this clarifier. Turning the clarifier off worked well on most signals and
I think this feature may convert some operators to sideband. In time with
more frequency stable radios on the market, the need to constantly tune
in stations may be a thing of the past eliminating the most common reason people won't use sideband.
Testing the squelch, I found it very smooth cutting in and out. There
was no pop or click as signals came in breaking the squelch. It also
worked very well on sideband. I'm not a squelch user myself because most
of them are erratic and at times choppy. I find more often than not, calls
get missed or parts of conversations are cut out because the squelch can't
be properly set. This one works pretty well. It's one worth giving a try.
On air transmission reports were very good. The audio was clear on both
modes and at all power settings. The modulation wasn't super compressed at
the lowest power settings as it is on some radios.
The auto calibrating SWR meter is very convenient, no more keying up at
either end of the band and calibrating the meter before you get your
reading. Just go to the channel, key up and there it is.
During the on air tests I didn't encounter any interference that
impeded communication. There was slight interference from stations within
a quarter mile the next channel over, but I would expect this from any
other radio and far worse on most.
The Galaxy filter did reduce the noise level at the audio end. You
won't see a reduction in S meter reading but it smoothes the audio out
reducing harsh spikes from reaching the audio amplifier. There is a cost
to this. Weak signals become difficult to understand with the high
frequency removed from the audio signal. This filter cuts the high
frequency out so well, the tone control has almost no effect on the audio.
Many signals seem muffled, but under extreme noise conditions, this may be
worth getting use to.
Galaxy DX 2547 Specifications
|| 26.9650 - 27.4050 MHz
|| Phase-Lock-loop (PLL)
| Synthesizer Frequency Tolerance
| Frequency Stability
||-30°C to +50°C
|| 50 Ohms
|| Standard SO-239 type
|| RF output Power/Antenna SWR/Received signal strength/MOD %
|| AC 120V, 60Hz or DC 13.8V
|RF Power Output
|| AM 4W; USB/LSB 12W PEP
| Antenna Connector
|| UHF Type, 50 Ohms
| AM Modulation
|| up to 100%
|| Better than -60 dB
| Unwanted Sideband
|| Better than -60 dB
|Sensitivity for 10 dB (S+N)/N
|| AM: 0.5 mV, USB/LSB: 0.15
| Adjacent Channel Rejection
||-60dB Image Rejection -50dB
|AGC Figure of Merit
||50 mV for l0dB Change in Audio Output
| Audio Power Output
|| 2.5W @ 10% Distortion
| Audio Response
|| 300 to 2500 Hz
This radio comes with both a detachable AC and DC power
cord. It's not a bad size for a camping trailer where the DC cord will
come in handy. In addition to a user
manual, Galaxy includes a service manual. This manual is complete with
schematics (except the Galaxy noise blanker PCB), exploded parts drawing,
PCB drawings, mic wiring, parts list, alignment procedures, adjustment
location drawing, test equipment setup, and block diagram. This hard copy
manual is worth a $20.00 bill, and more when you need it. Galaxy warranties
the radio for 2 years from the date purchased or if you lost your receipt,
26 months from the date of manufacture. A little note from the warranty
policy page may be of interest to the readers. Galaxy uses a "R"
as the first character of the serial number to denote a refurbished
radio. Always check for this when you make or receive a new purchase.
One thing I would change, a small
one but an important one, the knobs should have a light colored pointer.
The position of the knobs is difficult to see even in decent lighting.
Although priced in the $320.00 to $360.00 retail range, it does have many features
for the money. This radio like other Galaxy models seems to be designed by
radio operators, not just hatched from an engineer’s desktop. It
certainly appears Galaxy did their homework on the user and engineering
level. The features that are desirable are there and work very well. Time
will tell if there’s room for a high quality 40-channel AM/SSB base
station CB radio in this seemingly 10-meter radio market. A market,
ironically that Galaxy was very instrumental in helping to create with
their 10–meter line of radios. ©CBWI