Specifications

ManualsBrandsM2 ManualsAmplifier2M-1K2

54 May 2013 ARRL, the national association for Amateur Radio

www.arrl.org

40° C, the fans come on to cool the RF deck

heat sink. If the temperature reaches 90° C, the

amplifier will shut down and the indicator

light on the front panel will come on. The am-

plifier can be reset by cycling the

READY

switch.

I used the amplifier for a number of long

WSJT attempts and also for the ARRL January

VHF Contest. Under those intense operating

conditions I never ran into any problems that

tripped the protection circuitry. The manual

indicates that it is unlikely for the amp to shut

down in an over-temp condition, and that was

my experience even running this amplifier flat

out for extended periods.

TR Switching

As noted earlier, I keyed the amplifier through

my existing sequencer, which itself is acti-

vated by a footswitch. As a result, I had no

problems with my preamps, or with timing for

keying the amplifier on CW. Testing in the

ARRL Lab, however, did show that the TR

relay is a bit slow to engage. The manual indi-

cates that the there is a 15 to 20 ms delay built

in before bias voltage is applied to the

MOSFET device.

This is consistent with what was seen in the

ARRL Lab. The TR switching circuitry in the

2M-1K2 is slow enough that the first character

may be lost during semi break-in CW opera-

tion or the first syllable may be truncated if

using VOX on SSB. For transceivers with ad-

justable delays, this problem can likely be

solved with a delay to match the amplifier’s

engagement time. Better yet, use a sequencer

to create the small delay before keying. There

is no problem if you’re using a mic with a

manual PTT switch or a footswitch on CW, or

for someone starting a digital transmission.

Documentation

The 21 page operating manual does a good job

of describing setup and operation. It also pro-

vides helpful background on the amplifier’s

capabilities and on the protection circuitry. I

found the troubleshooting section helpful as

well. For those inclined to “open up the hood”

there are clear schematics of all of the boards

as well as pictures. M

has also added helpful

information on WSJT operation, knowing that

many who are interested in high power opera-

tion will also want to use that mode to work

either scatter or EME.

On the Air

I was able to use the amplifier for several

weeks with regular over the air contacts and to

give it a real workout during WSJT skeds and

during the ARRL January VHF Contest. I

live in Connecticut where there are quite a

few locals who know me well and have heard

my signal at high power using my TS-2000

and 8877 amplifier for many years. A big con-

cern in a relatively congested area for 2 meter

operation is to be sure you have a clean signal.

Living in a good location with four high gain

antennas means I am pushing a lot of RF in

the direction the array is pointed. I have

always gotten good reports on my signal —

how would that hold up with the 2M-1K2?

Bottom line is that after a good deal of testing,

all reports came back with excellent audio

quality. Testing showed that the TS-2000 bare-

foot and with the amplifier inline sounded the

same, confirming the amplifier was “clean”

over the air. I actually ran the amplifier at

slightly higher power most times (around

1200 W) versus my tube amplifier (800 W).

Overall it was a fun experience to use a new

piece of equipment and have it perform as it

was supposed to. For me the appeal of the am-

plifier is the small size, broadband tuning, low

voltage supply and lower noise level compared

to my own tube amplifier. Solid state operation

near the legal limit at 2 meters is now a reality,

and M

offers an excellent candidate for those

choosing to head in that direction.

Manufacturer:

Antenna Systems,

4402

N. Selland Ave, Fresno, CA 93722; tel 559-

432-8873; www.m2inc.com.

See the Digital Edition of QST for a video overview

of the M

2M-1K2 high power 2 meter ampliﬁer.

Reprinted with permission from ARRL