MFJ MFJ-926 User Manual

Automatic Antenna Tunner

Model MFJ-926

INSTRUCTION MANUAL

VERSION 1A

CAUTION: Read All Instructions Before Operating Equipment

MFJ ENTERPRISES, INC.

300 Industrial Park Road

Starkville, MS 39759 USA

Tel: [phone] Fax: [phone]

COPYRIGHT 2006 MFJ ENTERPRISES, INC.

C

MFJ-926 Remote Automatic Antenna Tuner

Introduction

The MFJ-926 Remote Automatic Antenna Tuner is designed to cover all frequencies ranging from 1.8-30
MHz. The multi-signal processing circuit switches inductance and capacitance as needed to match the
impedance of the antenna system with your radio. Fast tuning, less than 2 seconds after initial tuning.
Two-Hundred memory channels store the minimum SWR value to make tuning fast.

Specification

Working Frequency: 1.8 – 30 MHz
Input Impendence: 50 Ohm
Max. Input Power: 200 Watts PEP
Min. Input Power: 10 Watts
Power Supply: 13.8V +/-10%
Current Drain: <0.8A
Auto Tuning Time: Approx. 2 sec. (first time tuning)
Memory Channels: 200
Weight: 4 lbs
Usable Wire Length: 6-30 MHz > 2.4 meters

1.8-30Mhz > 8.0 meters

Antenna

+13.8VDC

Source

50-ohm Coax

Figure 1. Installation Block Diagram

MFJ-926

RF Ground

© 2006 MFJ Enterprises, Inc.

MFJ-926 Remote Automatic Antenna Tuner Instruction Manual

WARNING

● Never operate the tuner with its cover removed. Contact with the components inside the
tuner while transmitting will result in painful RF burns.

● Locate the tuner so that the top antenna terminals are not accessible during operation. The
antenna connection will have high voltage while transmitting.

● Disconnect the tuner and radio from an antenna before lightning storms. DO NOT
ATTEMPT THIS DURING A STORM

● Never exceed tuner specifications.

● Do not transmit with a high SWR for extended periods of time. Check all connections if this

occurs.

Installations

The MFJ-926 can be installed for mobile or base station operation. For mobile operation the antenna
terminal should be connected to a suitable antenna. The ground should be connected to the body/frame of
the vehicle with a short heavy gauge wire or strap. Keep this connection to a minimum. Base station
installations may vary but all installations must have a suitable ground and a wire/antenna of suitable
length depending on the operating frequency.

Connections

1. Connect the supplied power cable to a 13.8VDC source. The RED wire should be

connected to the positive (+) terminal of the source while the BLUE should be connected
to the negative (-) terminal. Check the polarity of the cable with a voltmeter before
connecting the auto-tuner. The 13.8VDC source must be capable of delivering a
minimum of 1 amp of current continuously. If the voltage is to low the tuner will not
power on.

2. Connect your transceiver to the SO-239 connector on the antenna tuner using a good

quality 50 ohm coaxial cable. The coax should be kept to a minimum length.

3. Connect a wire antenna / mobile whip to the antenna terminal on the top of the tuner.

The antenna must be a suitable length for proper tuning. Lower frequencies will require
longer antennas while higher frequencies require shorter lengths. If the antenna wire is to
short the tuner will not match the impedance of the antenna to the transmitter.

4. Connect a suitable ground to the ground point on the bottom of the tuner. Read the

section below on ground systems.

Ground System and Counterpoise

The MFJ-926 must be connected to a good electrical ground. A good ground can prevent accidental
shocks, interference to other electronics and keep RF out of out of your shack. Use a heavy gauge wire or
metal strap to connect to a large as possible metal object. In addition to a good ground, a counterpoise
wire must be installed at a quarter wave length of the operating frequency.

Caution:

1. To insure the proper tuning, the antenna must have enough length (See Antenna Length Section

below).

2. Do not install a balun, it will cause a tuning problem. Calculation of undesirable antenna length:

Length of half wave = 300 / operating frequency (MHz) x ½.

© 2006 MFJ Enterprises, Inc.

2

MFJ-926 Remote Automatic Antenna Tuner Instruction Manual

Please avoid using the antenna length close to that of a half wave or multiple of a half wave in length.

WARNING

● Never place your antenna in a location where it may come into contact with POWER
LINES. SERIOUS INJURY or DEATH may result if the antenna were to make contact
with power lines.

● Locate the tuner and antenna in a manner that is not accessible during operation. The
antenna will have high voltage while transmitting.

CAUTION

For operator safety, a good outside earth ground or water pipe ground should always be
installed and connected to the ground terminal of the MFJ-926. Make certain the safety ground
also connects to the transmitter and other station accessories. A wing-nut post marked
GROUND is provided for ground and counterpoise wire connections.

ANTENNA LENGTH

The MFJ-926 Remote Automatic Antenna Tuner will match an antenna of suitable length to any
transmitter. Lower frequencies require longer antennas while higher frequencies require shorter lengths.
The MFJ-926 does have a limited amount of inductance and capacitance and will only match antennas
within its limits. The antenna may be to long if the tuner does not find a match. Simple testing methods
can be used to determine how to adjust your antenna.

OPERATION

After verifying each of the connections to the tuner, choose your desired frequency and switch the
transmit mode as desired. Press the PTT key, the MFJ-926 will automatically tune. You will hear some
“click click” noisy, it means the auto tuner is tuning.

When you go back to the frequency which is tuned before, MFJ-926 will pickup the existing L/C
combination from memory setting and match the system.

To reset the tuner, just simply disconnect the power from the MFJ-926.

TECHNICAL ASSISTANCE

If you have any problems with this unit, check the appropriate section of this instruction manual. If this

does not reference your problem, you may contact MFJ Technical Service at 662-323-0549 or the MFJ
Factory at 662-323-5869. Please have your unit, this manual, and anything else associated with this unit

available on your station so the technician can properly answer your questions.
Other ways to contact MFJ are by facsimile at 662-323-6551, by email at [e-mail]
or by mail at:

,

MFJ ENTERPRISES, INC.
300 Industrial Park Road
Starkville, MS 39759

When writing MFJ, please send a complete description of your problem, an explanation of exactly how
you are using your unit, and a complete description of your station.

© 2006 MFJ Enterprises, Inc.

3

MFJ-926 Remote Automatic Antenna Tuner Instruction Manual

FULL 12-MONTH WARRANTY

MFJ Enterprises, Inc. warrants to the original owner of this product, if manufactured by MFJ Enterprises,
Inc. and purchased from an authorized dealer or directly from MFJ Enterprises, Inc. to be free from
defects in material and workmanship for a period of 12 months from date of purchase provided the
following terms of this warranty are satisfied.

1. The purchaser must retain the dated proof-of-purchase (bill of sale, canceled check, credit

card or money order receipt, etc.) describing the product to establish the validity of the warranty
claim and submit the original or machine reproduction of such proof of purchase to MFJ
Enterprises, Inc. at the time of warranty service. MFJ Enterprises, Inc. shall have the discretion to
deny warranty without dated proof-of-purchase. Any evidence of alteration, erasure, of forgery
shall be cause to void any and all warranty terms immediately.

2. MFJ Enterprises, Inc. agrees to repair or replace at MFJ's option without charge to the

original owner any defective product provided the product is returned postage prepaid to MFJ

Enterprises, Inc. with a personal check, cashiers check, or money order for $10.00 covering

postage and handling.

3. MFJ Enterprises, Inc. will supply replacement parts free of charge for any MFJ product
under warranty upon request. A dated proof of purchase and a $8.00 personal check, cashiers

check, or money order must be provided to cover postage and handling.

4. This warranty is NOT void for owners who attempt to repair defective units. Technical

consultation is available by calling [phone].

5. This warranty does not apply to kits sold by or manufactured by MFJ Enterprises, Inc.

6. Wired and tested PC board products are covered by this warranty provided only the
wired and tested PC board product is returned. Wired and tested PC boards installed in the

owner's cabinet or connected to switches, jacks, or cables, etc. sent to MFJ Enterprises, Inc. will be
returned at the owner's expense un-repaired.

7. Under no circumstances is MFJ Enterprises, Inc. liable for consequential damages to

person or property by the use of any MFJ products.

8. Out-of-Warranty Service: MFJ Enterprises, Inc. will repair any out-of-warranty product

provided the unit is shipped prepaid. All repaired units will be shipped COD to the owner. Repair
charges will be added to the COD fee unless other arrangements are made.

9. This warranty is given in lieu of any other warranty expressed or implied.

10. MFJ Enterprises, Inc. reserves the right to make changes or improvements in design or

manufacture without incurring any obligation to install such changes upon any of the products
previously manufactured.

11. All MFJ products to be serviced in-warranty or out-of-warranty should be addressed to
MFJ Enterprises, Inc., 300 Industrial Park Rd, Starkville, Mississippi 39759, USA and must

be accompanied by a letter describing the problem in detail along with a copy of your dated proof­of-purchase and a telephone number.

12. This warranty gives you specific rights, and you may also have other rights, which vary
from state to state.

MFJ ENTERPRISES, INC.

300 Industrial Park Road
Starkville, MS 39759

MFJ-926 Manual

Version 1A

Printed In U.S.A.