Inside The Galaxy DX 2547 AM/SSB CB Base Station Radio
The first thing I noticed after removing the top and bottom covers was the mobile chassis mounted in the base chassis. At first I was disappointed thinking this was a cheaply made base radio. What they have done was use the aluminum chassis of their mobile CB radio and designed a base chassis that accepts this sub -assembly utilizing the mobile chassis for the heat sink.
Most base radios were nothing more than a mobile circuit board in a box with extra features and a built-in power supply. Even the very popular Cobra 2000 was a Cobra 148 in a nice box with a frequency counter two meters and extra features. So there's really nothing different here.
The transformer is a small version of the one used in the 100 watt RCI base radios. It's a toroid type and I would expect it to power this radio with the dual final modification and still have more in reserve. In addition, the power supply regulator has a large heat sink attached to the rear of the radio.
Speaking about a dual final modification, the circuit board has spaces for another 2SC1969 and other components required to increase the output power to that of a 10-meter dual final 30 Watt radio. To get optimum output and truly clean sideband transmission a matched pair of 2SC1969 should be used. I mention this because the modification sheet I have seen calls for one 2SC1969 not a matched pair. I will cover this in another article sometime in the future.
DX 2547 Transformer
The following are some power supply voltage measurements made at no load, receive only, and at different transmitter power levels:
|SSB 14 Watts PEP||13.72V|
|SSB 22 Watts PEP||13.69V|
The layout is very clean. There are no components on the back of the circuit board. The main circuit board is through hole technology. This will make many dealers happy. Most dealers don't like working on surface mount circuit boards. There are some boards in this radio that are surface mount. It's the coming technology whether we like it or not. More and more components are are only available for SMT.
Peaking the transmitter was disappointing at first. sideband wouldn't increase at all. The AM carrier would increase to around 6 Watts and the peak modulation would only swing to 12 Watts. After going over and over the tune-up, I realized the the heatsink by the final was getting very hot. Finally I was able to get 22 Watts PEP sideband. and 6 Watts with a swing to 18 Watts on AM by spreading L29 out. The heatsink didn't get as hot after spreading this coil.
The controls for power and modulation are as follows:
|AM High Power||VR14|
|AM Low Power||VR18|
Mechanically it is well structured and should last for many years. The components on the main PC board are well marked and easy to locate. The top and bottom covers may be a tad too large. I recommend putting the side screws in first and lining up the covers while tightening them. Then install the top, bottom, and rear screws. I found installing the top and bottom screws first, the covers overlapped at the side seam and was impossible to line them up without doing damage.
And for the operators that like toys in their radios, There's room for echo boards, speech processors, sound recorders, noise toys and whatever your heart desires. There isn't a lot of room on the front panel for switches though.
The front bezel has knockouts for other switches and maybe controls. It seems that there are other plans for this bezel. I hope it's only for Galaxy. I've seen to often what happens when a radio case is used for another product.
The end user thinks they are the same inside, when in fact they can be quite different. The cheaper model gives a bad rape to the better unit, after all it's the same, it looks the same, it must be the same. Just the company that charges more is screwing the public...right? As wrong as these theories and assumptions are, the public hasn't learned that a radio can look the same but be totally different inside. One example is the Magnum 257.
Magnum International did many hours of engineering on this unit. Most of this engineering didn't go into the look alike radios. This radio has been hurt by other look alike radios produced by the same Korean factory. Some were single final radios.
The distributors and dealers didn't go out of their way to point this out. And we didn't see Radio Shack advertise their copy was unconvertible. In fact Radio Shack had it in the contract that the radio must not be convertible and if it could be the factory would pay dearly in damages. It's psychology, would you pick up a snake that looks like one that bit you before?