MFJ VersaTuner V, MFJ-989D Instruction Manual

Model MFJ-989D

CAUTION: Read All Instructions Before Operating Equipment

MFJ ENTERPRISES, INC.

Tel: [phone] Fax: [phone]

VERSION 2A

INSTRUCTION MANUAL

300 Industrial Park Road

Starkville, MS 39759 USA

COPYRIGHT 2014 MFJ ENTERPRISES, INC.

C

MFJ-989D VersaTuner V Instruction Manual

DISCLAIMER

Information in this manual is designed for user purposes only and is not intended to supersede
information contained in customer regulations, technical manuals/documents, positional handbooks, or
other official publications. The copy of this manual provided to the customer will not be updated to
reflect current data.

Customers using this manual should report errors or omissions, recommendations for improvements, or
other comments to MFJ Enterprises, 300 Industrial Park Road, Starkville, MS 39759. Phone: (662) 323­5869; FAX: [phone]. Business hours: M-F 8-4:30 CST.

2

MFJ-989D VersaTuner V Instruction Manual

Introduction

Thank you for selecting the MFJ-989D. Over the years, the MFJ-989 has earned an impressive
reputation as the world's most popular legal-limit tuner. Now, the "D" model features a number of
important upgrades that make it even better. Because of these improvements, you'll enjoy higher
efficiency, greater operating convenience, true peak-reading power measurements, extended frequency
coverage, plus many more refinements in both design and appearance. Even the cabinet is new, with a
nearly indestructible multi-color Lexan front panel and an interior layout that improves component Q
and reduces losses. Top to bottom, the Versa Tuner-V has evolved into a truly superior piece of
equipment built to deliver years of faithful service.

Circuit Overview

The MFJ-989D Versa-Tuner V incorporates five highly useful stand-alone station accessories into a
single package. The block diagram below shows how these five building blocks are organized:

Jumper

Bal.
Line

Transmitter

1. SWR/

Wattmeter

2. Antenna
Selector

Wire
Coax-1

Coax-2

5.

Balun

4.

3. Load

T-Network

1.) SWR / Wattmeter: Dual-range (300W/3kW) power meter features precision cross-needle
movements with LED illumination, a compensated directional coupler, and dual detectors for measuring
average and instantaneous-peak power. Circuit is identical to our MFJ-815C TrueActive (TM) stand-
alone meter.

2.) Antenna Selector Switch: Heavy-duty ceramic switch with silver-plated contacts and six positions
for routing a variety of loads to your transmitter or amplifier.

3.) Dummy Load: Precision non-inductive 50-Ohm load resistor, convection cooled and rated for 300
Watts dissipation (same as the MFJ-260C Dummy Load).

4.) Legal-Limit Tuner: MFJ's proven T-network features 500-pF wide-spaced air-variable capacitors
plus our unique 24-uH AirCore (TM) rotary inductor for continuous coverage of the HF spectrum.
These rugged components allow you to match virtually any antenna load you're likely to encounter.

5.) 1:1 Balun: Features two massive 2.4-inch ferrite cores wound with high-voltage polyethylene wire
and terminated to rugged ceramic feed-through posts on the back panel. MFJ's top-of-the-line high­power Guanella current-style balun.

Before attempting to use your MFJ-989D for the first time, we urge you to read through the entire
manual. Doing so will help you gain familiarity with all of the MFJ-989D's many functions and features.
You'll also find useful technical information applying to all tuners and solutions for difficult-to-match
antennas.

3

MFJ-989D VersaTuner V Instruction Manual

MFJ-989D Specifications

Power Rating: 1500-Watts, SSB/CW
Matching Range: 6.5-3200 Ohms at 1500 Watts input
Configuration: T-Network with rotary inductor
Meter Range: 300 and 3-kW forward, 60 and 600-W reflected
Meter Detection: Averaged and instantaneous-peak, active-circuit detection
Dummy Load: 50-Ohms non-inductive, 300-W, convection cooled
Antenna Selector: 6-position multi-section heavy-duty ceramic
Balun: Guanella-style 1:1 current, dual-core 2.4-inch toroid form
External Power 12-vdc, 2.1mm rear-panel jack or internal 9-Volt battery (see text).
Dimensions: 12-7/8" W x 6" High x 11-5/8" D (32.7 x 15.2 x 29.5 cm)
Weight: 9 pounds (4.08 kG)

Power Requirement

The upgraded MFJ-989D requires a power source to run its SWR/Wattmeter circuitry. Power may come
from one of two sources:

1.) 9-Volt Battery: To install a 9-volt battery, access the internal holder and snap clip by removing the
12 cabinet screws and lifting off the tuner cover. The holder is mounted on the upper right corner of the
front panel. We strongly recommend installing a battery, even if you intend to use an external power
source. Doing so provides backup voltage to operate the meter and also prevents the battery snap clip
from floating loose inside the cabinet where it could contact high RF potentials. If you elect to omit the
battery, make sure the snap clip is anchored solidly to the battery holder where it was wedged for
shipping.

To extend battery life, the tuner has built-in RF-sensing that applies power to the meter electronics only
when a transmit signal is applied. After a short period of transmitter inactivity, power is removed
automatically.

Important Note: The 9-V battery powers only the meter electronics. It does not power the meter LEDs.
You must supply external DC to illuminate the SWR meter.

2.) 12-VDC External Power: The Meter Lamp power jack is located above the Transmitter connector
on the rear panel. Apply power from any filtered dc wall adapter (MFJ-1312D or equivalent), or use
your station's 13.8-Vdc supply. A cord fitted with a 2.1-mm plug is supplied with the tuner for this
purpose. If you make your own supply cord, connect +12 volts to the center pin and ground the outer
sleeve, as shown below:

4

MFJ-989D VersaTuner V Instruction Manual

­+

2.1 mm

+

-

Important Note: You don't need to disconnect the battery when using external dc power. It is
protected from back-feed and won't be damaged by the other source.

Important Warning: Never connect an ac-voltage or positive-ground source to the Meter Lamp jack
or permanent damage may result!

Front Panel Layout

MFJ VersaTuner V

INDUCTANCE

0 5 0

3

TRANSMITTER

1

0

56

2

ANTENNA

SELECTOR

4

10

Coax-1

Dummy

Load

Coax-2 Direct

0

Coax-2

Wire/Bal

Line

Coax-1 Direct

ANTENNA

10

RANGE POWER LAMP

Hi

Low

7

PK

Avg

8

On

Off

9

MFJ-989D

1.) Transmitter Tuning Capacitor: Series capacitor on the Transmitter side of the T-network.
Maximum capacity at 0

knob setting and minimum capacity at 10.*

2. Antenna Tuning Capacitor: Series capacitor on the Antenna side of the T-network. Maximum
capacity at 0 and

3. Rotary Inductor: Continuously adjustable shunt Inductor with maximum inductance at 000
minimum inductance at 090

minimum capacity at 10.*

and

.*

4. Antenna Selector: Routes signals inside the tuner and selects Antenna.

5. Forward Power Scale: Displays Forward Power (300-W or 3-kW scale).

6. Reflected Power Scale: Displays Reflected Power (60-Watt or 600-Watt scale).

7. Range HI/LO: Selects the metering circuit power range (x1, x10).

5

MFJ-989D VersaTuner V Instruction Manual

8. Power PK/AVG: Selects the meter detection (Peak or Average).**

9. Lamp On/Off: Turns meter's LED lighting on or off.**

NOTE* The control scales track frequency rather than component value. Tuned circuits typically
require progressively lower values of L and C as frequency increases.

NOTE** External 12-volt source is required for LED lighting.

Rear Panel Layout

BAL LINE

6

WIRE

7

Install Jumper For

Balanced Line

Operation

<

COAX-1

METER LAMP

1

GND

3

COAX-2

5

4

12V DC

TRANSMITTER

2

1. Meter Lamp: 2.1-mm coaxial power jack accepts 12 vdc to operate the LED meter lamps and the
metering circuit (see text)

2. Transmitter: Accepts PL-259, connects transceiver or amplifier to tuner.

3. Coax-1: Accepts PL-259, connects antenna #1 to tuner routing switch.

4. Coax-2: Accepts PL-259, connects antenna #2 to tuner routing switch.

5. GND: Chassis ground, connects tuner to station's ground system.

6. Bal Line: Antenna side of the 1:1 balun, accepts balanced feedlines.

7. Wire: terminal post (Wire) accepts single-wire antennas. To feed balanced antennas through the
balun, the Wire terminal is connected to the terminal post below with a jumper (see text).

6