12 MONTH LIMITED WARRANTY
MFJ Enterprises, Inc. warrants to the original owner of this product, if manufactured by MFJ
television sets, metal surfaces, computers,
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.
I. 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, or 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 under warranty, provided the product is returned postage prepaid to MFJ Enterprises, Inc.
with a personal check, cashiers check, or money order for $7.00 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 $5.00 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 (662) 323-5869.
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 unrepaired.
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
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. reserv es 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 Road, Starkville, Mississippi 39759, USA and must be accompanied by a letter describing
the problem in detail along with a copy of your dated proof-ofpurchase.
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 Rd
Starkville, MS 39759 USA
MFJ-121 Dual Time Atomic Clock
Instruction Manual
The MFJ-121 works by receiving the time radio signal generated by the US Atomic Clock
in Colorado. Any place that can receive the signal can use the MFJ-121. Any place
receive the signal will have to set the time manually. The Atomic Clock in
the US Department of Commerce's National Institute Standards and Technology.
reception of the signal, avoid placing your MFJ- 121 near
or any other electrical device that may interfere with the reception of the radio signal.
FCC Statement
The MFJ- 121 might cause TV or radio interference when operating properly. To determine
whether the MFJ-121 is causing interference, take out the batteries to turn it off. If the
interference goes away, the MFJ-121 is causing the interference. Try to eliminate the interference
by reorienting the MFJ-121 and/or increasing the separation between your equipment and the MFJ-
121. If you cannot eliminate the interference, the FCC requires that you stop using the clock.
Display and Mounting
The upper LCD display show the time and radio signal mark. The lower LCD display can be set
to another time zone. The unit can be placed on a desktop by pulling out the stand at the back or
mounted on a wall (mounting hardware not included).
Battery Replacement and Initialization
The MFJ- 121 uses two AAA batteries (not included). Open the battery cover and insert the
batteries according to the polarity shown inside the battery compartment. If the LCD Display
becomes dim, replace the batteries with new ones.
Setting the Upper LCD Display
display any curves. Try to rotate the unit or place it in another location to achieve better reception.
After setting the 12HR or 24 HR display mode, press the "SET' button once to bring the unit to time
Setting the Time Zone
With the MFJ-121 in the normal time display mode, move the slide switch on the back of the clock
to the "TIME" position. Then press the "SET" button. The upper LCD will show "-0 HR", "-1
HR", etc. (It will be "-0 HR" if no time zone was previously selected). Select the appropriate time
zone by pressing the A button to increase the number. Please refer to the table below for setting the
time zone of your area in the USA.
Time Zone Standard Time Setting
Pacific "-8 HR"
Mountain "-7 HR"
Central "-6 HR"
Eastern "-5 HR"
GMT "-0 HR"
Setting the Lower LCD Display
With the MFJ-121 in the normal time display mode, move the slide switch on the back of the clock
to the "TIME II" position. Follow the same procedure as Setting the Upper LCD Display.
Daylight Savings Time
The time receiver in the MFJ- 121 will automatically detect Daylight Savings Time. This
feature cannot be disabled. The MFJ- 121 will automatically adjust the time during
time so you will not have to change the time zone. During Daylight Savings Time the symbol "*
D.S.T" will be shown above the seconds on both LCD displays. If you live in an area that does not
observe Daylight Savings Time or want to display GMT, you must set the Time Zone -1 HR from
the current setting to compensate.
Note: The number following the "-X HR" indicates the number of hours difference from
GMT.
After setting the appropriate time zone, press the "SET" button again to proceed with setting the 12
HR or 24 HR time Display
Setting 12 HR or 24 HR Display
The LCD should now display a flashing" 12" or "24" and "H" that is not flashing. Press the A
button change between 12 HR and 24 HR time display mode. After selecting the time display
mode, press the "SET" button to proceed to Setting the Time Manually.
Setting the Time Manually
Since the unit works on receiving the time radio signal, there may be locations that the signal
and cannot he properly received. Under such conditions, the radio signal mark will
Re-install the batteries or press the "TEST" button to initialize the reception again.
still cannot be received, the time should be set manually.
setting mode. The hour digits will begin to flash. Press the A button to change the hour digits to the
proper time. Press the "SET" button again and the minutes digits will begin to flash. Press the A
button to change the minutes digits to the proper time. Press the "SET" button again and the
seconds digits will begin to flash. Press the A button to change the seconds
time. After setting the hours, minutes, and seconds, press the SET button once to return to the
normal time display. Then move the slide switch back to the "LOCK" position.
Note: Returning the slide switch to the "LOCK" position at anytime during the setting
procedure will cause the LCD to remain at the last step completed. To ensure proper operation of
the MFJ-121, the slide switch should not be returned to the "LOCK" position until the LCD
displays the time with no digits flashing.