Better Music Builder DX-211 Especificaciones descargar pdf (Pagina 4)

From March 2000 QST © ARRL

–10 –8 –6 –4 –2 0 2 4 6 8 10

–80

–70

–60

–50

–40

–30

–20

–10

Frequency Offset (kHz)

Reference Level: 0 dB PEP

2 4 6 8 10 12 14

18 20 22

–140

–130

–120

–110

–100

–90

–80

–70

–60

Frequency Sweep: 2 to 22 kHz from Carrier

Reference Level: - 60 dBc/Hz

Vertical Scale: dBc/Hz

as you go, you can actually begin to

understand how all these pieces come

together to make a radio. Altogether, we

spent close to 60 hours building the review

radio, including the SSB adapter and noise

blanker options.

Assembly begins with the control board

and the front panel (display) board. A

photograph of the completed control board

appears in Figure 5. Once these are

finished, you are instructed to add a few

components to the main board—the RF

board—and then take some preliminary

resistance measurements. Some of the

enclosure panels are assembled and the RF

board is temporarily installed. The display

board and the front panel board are then

plugged into the RF board in preparation

for some initial power-on tests.

Wait. Did that say “plug in” these

boards? Yes, that’s right. There are virtually

no wiring harnesses or point-to-point

wiring in the K2. All the connections

between the subassembly circuit boards are

accomplished with mating multipin

connectors. Elegant!

Once I had reached this point I plugged

in the power supply cable and—with

fingers firmly crossed—pushed the ON

button. ELECrAFt popped up in the display,

shortly followed by 7100.0! Success! It

worked. Now to run through the first round

of alignments… But wait. The buttons

didn’t seem to be responding properly. I

pressed a few buttons, held the LOCK

button, then pressed it again to return to

normal VFO operation. Now everything

seemed fine—but there must be something

that’s not quite right. Now what? It was 10

PM, and I wanted to work on it a bit longer.

I sure couldn’t call Elecraft at that hour…

Enter the Internet

Regis—I’ve decided to use one of my

“lifelines.” There’s a K2 e-mail reflector

with lots of other builders on line. I

wondered if anyone else had run into this

problem. I fired off a quick message to the

reflector and waited for a response.

I received a quick reply from Tom

Hammond, N

SS. Tom is one of the “Field

Testers” who built one of the first 1

kits and provided lots of feedback and

suggestions to Wayne and Eric. Tom told me

to check the solder connections on the

pushbuttons. A few other replies came in

from builders who hadn’t run into this type

of problem, but they encouraged me to make

a more thorough visual inspection. It was

getting late; I closed up shop for the night.

The following day I decided to give

Wayne a call. He helped me narrow it down

to the A=B and RIT switches. Wayne

explained that two of the switch posts feed

a signal through from one portion of the

circuit board to another, and he believed

that that was the source of my problem.

After reheating the posts and flowing on a

bit more solder, the problem was solved.

It is certainly possible to build a K2

without Internet access, but there is a

wealth of information available there. In

fact, this may be one of Elecraft’s most

valuable assets. Many questions are

answered by individuals who encountered

similar problems. In addition, there are

discussions about circuit modifications and

updates from Elecraft.

The technical support from Elecraft is

excellent. Wayne and Eric monitor the

reflector, and if they see a question that

wasn’t answered satisfactorily they will

soon fire off a note with the corrections or

clarifications. Of course for real tough

problems, e-mail sent directly to Elecraft

or a phone call to their technical support

line is sure to get you the help you need.

What other manufacturer lets you com-

municate directly with the design team?

Just monitoring the reflector can be

Figure 1—Worst-case spectral display of

the Elecraft K2 transmitter during two-

tone intermodulation distortion (IMD)

testing. The worst-case third-order

product is approximately 29 dB below

PEP output, and the worst-case fifth-

order product is down approximately 44

dB. The transmitter was being operated at

10 W PEP output at 28.350 MHz.

Figure 2—Worst-case spectral display

of the Elecraft K2 transmitter output

during composite-noise testing. Power

output is 10 W at 3.52 MHz. The carrier,

off the left edge of the plot, is not

shown. This plot shows composite

transmitted noise 2 to 22 kHz from the

carrier.

Figure 3—CW Keying waveform for the

Elecraft K2 showing the first two dits in

full-break-in (QSK) mode using external

keying. Equivalent keying speed is 60

WPM. The upper trace is the actual key

closure; the lower trace is the RF

envelope. Horizontal divisions are 10

ms. The transceiver was being operated

at 10 W output at 14.2 MHz.

Figure 4—The three main circuit boards and their corresponding parts bags. At this

stage I had completed the control board and was working on the display board.

1 2 3 4 5 6 7 8 9

Comentarios a estos manuales

Sin comentarios

Better Music Builder DX-211 Especificaciones Pagina 4

Comentarios a estos manuales

Relacionado con productos y manuales para Amplificadores de audio Better Music Builder DX-211