M2 2M-1K2 Especificações descarregar pdf (Página 2)

QST

– Devoted entirely to Amateur Radio www.arrl.org May 2013 53

brief sporadic E openings on 2 meters and had

to wait several agonizing minutes before I

could run high power!

Two fans come on at startup to keep the built

in power supply cool. There are also two fans

on top of the amplifier that come on to cool the

RF section as needed. They would usually

come on for transmissions longer than a min-

ute or so, or when I was doing some intense

heavy duty cycle operating during a contest.

Even with all fans going, the noise level in my

shack was far lower than the normal level for

my 8877 tube type amplifier that I use on

2 meters.

The LDMOSFET device at the heart of the

2M-1K2 needs only a few watts to drive it to

maximum output. Recognizing that many typ-

ical transceivers run considerably more power,

built in a 10 dB attenuator so that the am-

plifier will operate at maximum power with

about 50 W drive. I set my TS-2000 drive

level at 45 W and found this consistently cre-

ated more than 1200 W of output power as

measured with my Bird wattmeter. See

Table 2 for the results of the ARRL Lab tests

at various drive levels. While using the ampli-

fier in JT Mode, the power output was around

900 W.

I did run into one issue along the way. When I

first received the amplifier, every time I turned

it on the noise floor rose in my receiver.

Typically it would jump about two S units,

more than enough to be problematic for seri-

ous 2 meter operators. Cycling the amplifier

on and off confirmed the noise was coming

from the new installation. I was able to use ex-

ternal relays to bypass the amplifier on receive,

indicating the noise was coming from the

Table 2

2M-1K2, serial number 201222

Manufacturer’s Speciﬁcations Measured in ARRL Lab

Frequency range: 144-148 MHz. As speciﬁed.

Power requirements: 180-264 V ac, As speciﬁed.

47-63 Hz, 15 A maximum.

Driving power required: 50 W As speciﬁed.

(maximum).

Power output: 1200 W PEP with As speciﬁed, typically:

50 W drive. RF Input RF Output* JT Mode*

(W) (W) (W)

5 335 335

10 580 580

15 760 760

20 920 840

25 1010 840

30 1090 850

35 1150 880

40 1200 920

45 >1200 960

50 >1200 1000

Spurious and harmonic suppression: 65 dB; meets

Not speciﬁed. FCC requirements.

Transmit intermodulation distortion: 3rd/5th/7th/9th order:

Not speciﬁed. –26/–43/–43/–52 dB.

Size (height, width, depth): 9 × 7 × 13 inches; weight, 20.6 lbs.

Price: $2995 with power supply; $2425 without power supply.

*RF Output using SSB and CW. JT Mode represents 100% duty cycle modes,

such as JT65 and FSK441 digital modes or FM voice.

Figure 5 — The 2M-1K2 rear panel.

WSJT — Digital Modes on VHF

WSJT by Joe Taylor, K1JT, is a free software program

for weak signal digital communication. Using a standard

transceiver with a computer interface, the program allows

communication with signal levels near or below the audible

signal level. It allows operators to work more stations than

they might ordinarily be able to work using SSB or CW.

WSJT offers several modes of operation. FSK441 is used

for meteor scatter. JT65 is used for EME (Earth-Moon-Earth)

and troposcatter, and JT6M is used for scatter mainly on

6 meters. Because it allows much greater ability to work

weak signals, much of the EME and scatter work on the VHF

bands is now done using WSJT. Stations with single Yagis

and medium power can routinely work scatter, long haul

troposcatter and EME by using the program.

To learn more about WSJT or download the program, you

can go to the WSJT home page at physics.princeton.edu/

pulsar/K1JT/. As discussed in the text, the 2M-1K2 has a

MODE

switch to be used for WSJT operation with its longer

duty cycle. —

Jeff Klein, K1TEO

amplifier. M

suggested returning the ampli-

fier, and testing on their end indicated that the

built in switching power supply was the source

of the noise. It was not a problem they had

heard about from others, so perhaps it was just

a single bad supply. M

sent a new amplifier

and supply and the problem was solved.

Amplier Protection

The 2M-1K2 comes with two important pro-

tection features. If the SWR at the output

reaches 2.5:1, the amplifier is deactivated and

the

VSWR/TEMP

indicator will let the user

know of the problem. The second feature is a

temperature sensor. If the amplifier reaches

1 2 3

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