Alinco DX-77T Informações Técnicas descarregar pdf (Página 3)

you won’t find the set mode functions all in

one place. Once you enter set mode, you’ll

have to push different buttons to access

different “menu” items. There’s a certain

logic to it, however, and after a while, you

will remember which settings reside behind

which buttons on the front panel.

To the Rear!

The back panel has jacks for connection

of the required external 13.8 V dc, 20A

power supply, an SO-239 antenna connec-

tion, and an attachment point for station

ground. RCA (phono) jacks for amplifier

relay and ALC controls, a five-conductor

connector for control of an external auto-

matic antenna tuner, and a 3.5 mm

REMOTE

jack for the optional Alinco ERW-4 com-

puter-control interface also are included.

This

REMOTE jack allows memory cloning

between two DX-77Ts. Simply connect the

two radios with a length of cable with

stereo 3.5-mm plugs on either end and ac-

tivate the clone feature.

Alinco says memory programming and

remote control are on the horizon for the

DX-77T. The software has not yet been de-

veloped, however. The control is via a serial

port connection directly from the computer’s

COM port to the stereo

REMOTE

jack on the

rear panel (Alinco supplies the ERW-4 cable

as an option). With suitable software, a user

will be able to set and control most of the

radio’s features including transmit and re-

ceive frequencies, output power, scanning

start and stop, priority, split, mode, RF gain,

AGC speed, noise blanker, CTCSS encoder,

tune mode, filter, and various menu func-

tions. The transceiver can report out its

S meter reading, PTT status, squelch status,

RIT status, memory channel information,

split mode, and VFO or memory mode.

Attachment of equipment for operating

the digital modes (RTTY, PACTOR,

AMTOR, etc.) is via the front panel micro-

phone connector. Alinco thoughtfully in-

cludes fixed-level audio at this connector for

easy hookup. The manual includes a micro-

Figure 3—Worst-case tested spectral

display of the Alinco DX-77T transmitter

output during composite-noise testing.

Power output is 100 W at 3.5 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 2

—

The default CW keying waveform

for the Alinco DX-77T showing the first two

dits in full-break-in (QSK) mode using

external keying. The 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

100 W output at 14.2 MHz. This is excellent

keying. The waveform was nearly identical

using semi-break-in mode with the “auto”

delay feature.

2 4 6 8 10 12 14 16 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

Figure 1—Worst-case spectral display of

the Alinco DX-77T transmitter during two-

tone intermodulation distortion (IMD)

testing. The worse-case third-order

product is approximately 30 dB below PEP

output, and the worse-case fifth-order

product is approximately 41 dB down. The

transceiver was being operated at 100 W

output at 21.250 MHz.

–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

phone wiring diagram. Two holes for mount-

ing bracket hardware are on each side of the

cabinet, although no mobile mounting

bracket is currently available from Alinco.

On the Air!

Operating the DX-77T is fairly simple.

A few seconds spent looking over the front

panel and a quick glance at the aforemen-

tioned “Quick Reference” table should be

enough to get most operators up and run-

ning. Once you have a feel for the interac-

tion between the

SELECT

and

DOWN

buttons, moving between frequencies,

bands, or memory channels is easy. Major

controls on this transceiver are very conve-

niently located, especially for right handers.

Voice operation is a simple matter of

selecting the mode with a few presses of

the

MODE button (the DX-77T steps

through its modes), tuning to the desired

frequency, setting the volume and squelch

levels, and away you go! Power output

level is limited to two levels: high power is

100 W output; low power is 10 W output

(an internal switch allows switching these

to 50 W and 5 W respectively).

The microphone gain level is factory set.

Those needing to make adjustments for

their individual voice characteristics will

find the location of and adjustment pro-

cedures for an internal mike gain control in

the manual’s maintenance chapter, but this

probably will not be necessary. Our review-

ers reported very good to excellent trans-

mit audio reports with the included mobile

microphone at the factory gain setting.

While this radio has an audio-level speech

processor, it does not have VOX.

Receive audio reports were mixed. The

included speaker is considerably smaller

than the front-panel grille would suggest.

Most reviewers felt that with the internal

speaker, the audio was somewhat tinny-

sounding. Predictably, using a larger exter-

nal speaker helped quite a bit. Alinco

located the external speaker jack on the front

panel. While this may be convenient in some

situations, for most station arrangements the

rear panel would be a better site for this jack.

Maybe an additional jack on the back would

provide the ultimate solution.

We had complained some about the ef-

fectiveness of the noise blanker in the

DX-70T. Apparently, Alinco listened and

made the noise blanker in the DX-77T

pretty aggressive. It works quite well on a

variety of pulse-type interference—such as

ignition noise—but it can impart some dis-

tortion to received signals under certain

band or noise conditions. Overall, though,

it will be an acceptable tradeoff for most

users, we believe.

Several features on this transceiver

make the DX-77T a good choice for the CW

operator. For starters, one of the most desir-

able CW options, a 500-Hz CW filter, al-

ready is installed! We peeked inside and

were pleased to find a real crystal filter, too,

not a ceramic job like the one in the

DX-70T. You can opt to receive CW sig-

nals on either side of zero beat—CWU or

CWL. This can help fight interference that

might be on one side or the other of the sta-

tion you’re trying to copy. You can zero

beat a CW signal either by matching its tone

in the CWU and CWL modes, or by a fea-

ture that allows matching the received

signal’s pitch to that of the CW sidetone.

Using the set mode, it’s possible to set the

sidetone pitch anywhere between 400 Hz

and 1000 Hz in 50 Hz increments.

The IF shift control allows minor

changes in the position of the IF filter’s

passband—always an excellent feature for

digging out weak signals under crowded

band conditions.

Radios in this price class typically don’t

include built-in CW keyers, so it was a pleas-

ant surprise to find one in the DX-77T. Nice

going, Alinco! The keyer in this radio will

generate code at between 6 and 50 words per

minute, and it can operate fully automatic

(iambic) as well as semi-automatic (bug

54 June 1998

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