MFJ VersaTuner V -989D User manual

INSTRUCTION MANUAL
CAUTION: Read All Instructions Before Operating Equipment
COPYRIGHT 2014 MFJ ENTERPRISES, INC.
C
Model MFJ-989D
VERSION 2A
MFJ ENTERPRISES, INC.
300 Industrial Park Road
Starkville, MS 39759 USA
Tel: [phone] Fax: [phone]

MFJ-989D VersaTuner V Instruction Manual
2
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) 323-
5869; FAX: [phone]. Business hours: M-F 8-4:30 CST.

MFJ-989D VersaTuner V Instruction Manual
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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:
1. SWR/
Wattmeter
4.
T-Network
3. Load
Wire
Coax-1
Coax-2
Balun Bal.
Line
2. Antenna
Selector
Transmitter
Jumper
5.
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 high-
power 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.

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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:

MFJ-989D VersaTuner V Instruction Manual
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+
-+
-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
TRANSMITTER ANTENNA
INDUCTANCE
0 5 0
ANTENNA
SELECTOR
RANGE POWER LAMP
Coax-1
Dummy
Coax-2 Direct Coax-1 Direct
Wire/Bal
Line
Coax-2
Load
On
Off
Hi
Low Avg
2
13
4
56
789
MFJ VersaTuner V
MFJ-989D
PK
010 010
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 minimum capacity at 10.*
3. Rotary Inductor:Continuously adjustable shunt Inductor with maximum inductance at 000 and
minimum inductance at 090.*
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).

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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
6
1
2
COAX-1
COAX-2
METER LAMP
TRANSMITTER
GND
BAL LINE WIRE
Install Jumper For
Balanced Line
Operation
12V DC
<
54
3
7
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).

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Installing the MFJ-989D
The block diagram below shows a typical tuner installation.
Station
Ground
Gnd
Gnd
Coax-1
Coax-2
Meter
Lamp Transmitter
Line
Ant #1 Ant #2 +12 vdc
Jumper
Wire
Balanced
Feed
Ant #3
Radio
Tuner
Here are some important installation guidelines:
1.) Tuner Location:Position the tuner for convenient access to all front panel controls. However, make
sure you cannot make accidental contact with RF-energized open-wire lines or longwire lead-ins
connected to the rear panel (serious RF burns could result). Also, never operate the tuner with the cover
removed!
2.) Transmitter Patch Cable:Use a short direct connection between your transmitter and the tuner. The
cable should be good-quality 50-Ohm stock that is rated for the full amount of power you intend to run.
Also, never install a balun between the tuner and transmitter or string ferrite beads on the cable!
3.) Tuner Grounding:Connect the tuner chassis directly to your station's ground system. Don't rely on
the patch cable to ground the tuner to your radio or amplifier.
4.) Lightning Protection:Make provisions to disconnect all antennas from your station in the event of
violent weather. Lightning arrestors may reduce damage from nearby strikes, but only disconnection can
reduce the odds of damage from a direct hit.
Important Warnings: Never install the tuner where you could come in contact with exposed open
wire lines connected to the rear panel. Also, never operate with the tuner cover removed. Finally,
always disconnect all antennas at the first sign of electrical storm activity!
As previously noted, the MFJ-989D incorporates five very useful station accessories into a single
package. Here are operating instructions for each one, beginning with the power meter and SWR bridge.
SWR/Wattmeter
The SWR bridge is configured at the Transmitter (or input) side of the tuner and it is always in-line with
the transmitter, regardless of the Antenna Selector setting. To measure forward and reflected power:

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[ ] Select a forward Power range (LO for 300-W or HI for 3-kW).
[ ] Select PK for peak-power readings or AVG for average-power readings.
[ ] View the Forward scale to read incident power.
[ ] View the Reflected scale to read reverse power.
[ ] For SWR, find the red curve closest to where the two meter pointers intersect. The red SWR curves
provide a reliable estimate of SWR without the inconvenience of adjusting a sensitivity control to
calibrate the meter. Each red line on the meter is marked with a SWR value.
1.) Power Readings: For continuous carrier (CW or FM) modes, Peak and Average power readings
should measure virtually the same. For SSB voice, Peak readings may measure 3 to 5 times higher than
the Average power, depending on speech characteristics and the amount of speech processing being
used. Two-tone-test Peak readings should measure twice the Average power readings. Readings taken
along the upper two-thirds of the meter scale are typically more accurate than those made along the
lower third.
2.) Measuring Power with SWR:When measuring transmitter power into a mismatched load
indicating reflected power, remember to subtract the Reflected Power reading from the Forward Power
reading: (Po = FP - RP).
3.) Precision SWR Readings:To obtain precise SWR data using the split meters, write down the
Forward and Reflected power measurements (in Watts) and plug them into the formula shown below:
SWR =
1 + Pr
Pf
1 - Pr
Pf
Pr = Reflected Power
Pf = Forward Power
Antenna Selector
The Antenna Selector is a heavy-duty six-position RF switch that routes the tuner's Transmitter input
line as described below:
Coax-1 Direct:Transmit line passes directly to Coax-1 output.
Coax-2 Direct:Transmit line passes directly to Coax-2 output.
Dummy Load:Transmit line passes directly to the internal 50-Ohm load.
Coax-1:Transmit line goes through the T-network to Coax-1 output.
Coax-2:Transmit line goes through the T-network to Coax-2 output.
Wire/Bal. Line:Transmit line goes through the T-network to the Wire terminal post.

MFJ-989D VersaTuner V Instruction Manual
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Always check the position of the Antenna Selector before applying RF power! If you fail to do so, you
may accidentally dump 1500 Watts into the 300-Watt dummy load with catastrophic results or find
yourself trying to adjust the tuner's controls while the network is bypassed! Also, never rotate the
Antenna Selector when RF power is being applied! "Hot switching" will cause severe arcing and
burning of the switch contacts -- and the sudden load interruption could damage your transmitter.
Important Warning: When operating your tuner, always check the position of the Antenna Selector
before applying RF power. Also, never change the Antenna Selector when RF power is applied!
Dummy Load
The tuner's internal dummy load features a precision non-inductive power resistor that maintains low
SWR across the entire HF spectrum. The load performs two important functions:
1.) Normalizing Transmitters To 50-Ohms: Use the load to pre-tune older transceivers or vintage
transmitters with tube-type PA amplifiers to normalize them for 50-Ohm output prior to routing through
the T-network.
2.) Accurately Measuring Transmitter Power: Use the load to check any radio running 300 Watts or less
for true peak-power power or average power output through the tuner's precision wattmeter.
The Dummy Load resistor is convection cooled through the bottom of the cabinet and is rated to safely
dissipate 300-Watts of applied RF for up to 30-seconds at a time. The minimum cool-down period
between power applications is specified at 2-minutes. Longer tune-up durations are possible at lower
power levels, but the continuous-duty power rating of the resistor is 25 Watts, so you must adjust the
key-down time accordingly.
Never apply power levels exceeding 300-Watts for even short durations. Doing so could permanently
alter the resistor's value or catastrophically destroy it. Heat damage to other tuner components could
result, as well!
Important Warning: Never tune a high-power linear amplifier into the MFJ-989D Dummy Load or
permanent damage will result!
1:1 Balun
A built-in Guanella-style current balun is used to transition from the tuner's unbalanced Wire terminal to
the Bal. Line output. The balun is wound on two massive 2.4-inch toroid cores with heavy polyethylene-
dielectric wire to ensure a high breakdown voltage for handling difficult high-impedance loads.
Windings are terminated to ceramic terminal posts mounted on the back panel, with a fourth lead
permanently grounded to the chassis (see diagram next page):

MFJ-989D VersaTuner V Instruction Manual
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Wire
Jumper Wire
Install
<
Bal. Line
Balun
To place the balun in line and energize the Bal. Line terminals, connect a Jumper from the unbalanced
Wire terminal post to the terminal post directly below it. The jumper-wire path is labeled on back panel
for reference. Note that the T-network is always in line when the Antenna Selector is switched to the
Wire/Bal. Line position.
T-Network
1.) The Network Configuration: The T-network gets its name from the distinctive shape of the
components making it up (shown below):
>
Transmitter Antenna
Inductor
This network configuration is especially practical for amateur-radio tuners because it can match an
unusually wide range of loads into 50-Ohm equipment. The T-configuration using two series capacitors
and a shunt inductor belongs to the high-pass filter family and, as such, it does little to suppress
transmitter harmonics. However, modern transceivers and amplifiers must meet stringent harmonic
suppression requirements on their own to satisfy FCC requirements, so there's little need for high-
frequency suppression in the tuner.
2.) The C-high L-low Rule: With three tunable elements(C-L-C), the T-Network is able to provide a
low-SWR match into a 50-Ohms system using many different component value combinations. As a rule
of thumb, we always look for a combination using the largest amount of capacitance (lower knob
settings) in combination with the smallest amount of inductance (higher counter setting). This ratio
ensures the lowest loss and greatest power handling capability -- with less chance of arcing over. When
tuning, it may help to recall the phrase: "See (C) high and look (L) low".