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Reviews Categories | Ham Shack Clocks | MFJ-121 / 121B Help

Reviews Summary for MFJ-121 / 121B
MFJ-121 / 121B Reviews: 23 Average rating: 3.1/5 MSRP: $69.95
Description: Large Display, Dual-Time LCD Atomic Clock for wall mounting or table top. Read both UTC and local time at-a-glance with the MFJ-121 dual atomic clock that displays 24/12 hour time simultaneously.
It's fully automatic! Just install batteries and tell it what time zone.... it actually synchronizes itself to the exact time daily.
It tunes into the radio signal emitted by the US Atomic Clock in Ft. Collins, Colorado to give you precise and reliable time. It receives automatic daily updates from the US Department of Commerce's National Institute of Standards and Technology.
Mounted in a handsome hard plastic frame, the MFJ-121 features HUGE, easy-to-see 2 inch tall by 1 1/2 wide LCD numerals and seconds display that makes it easy-to-read from across the room.
Mounts on wall or Desk mount. Perfect for the shack, emergency office or professional office.
Product is in production.
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K6RWM Rating: 5/5 May 26, 2012 02:44 Send this review to a friend
Excellent Product  Time owned: 3 to 6 months
This is a very nice clock for the ham shack. I have owned it for several months now, and I like the UTC/local time zone feature. It also has a light that provides just enough illumination to read the clock easily in a dimly lit radio operating position. The large numerals are very easy to read.
WA2ILB Rating: 5/5 Nov 12, 2011 07:53 Send this review to a friend
Very Nice!  Time owned: 0 to 3 months
I completely agree with W9IQ's review.

I live in extreme northern NH and the clock will not synchronize with Bolder, CO during the day because of the distance involved. Also the clock needs to be at least a foot away from any equipment with a microprocessor in it and the clock need to be broad side to the direction of Bolder, Co to maximize the low frequency signal strength of the time transmitter. If you are in an RV or a boat the signal may not be strong enough to synchronize every time.

This clock is definitely a keeper!
N7SOC Rating: 5/5 Mar 26, 2011 18:46 Send this review to a friend
great clock  Time owned: 3 to 6 months
love the large numbers....clock locked onto synchro overnight...has been accurate ever since...was exactly what i was looking for..both utc and local...had no problem with dst...utc time stayed as it should and local advanced...absolutely no problems with this clock...would rec., n7soc
N8QH Rating: 4/5 Jan 14, 2011 09:21 Send this review to a friend
OK with good WWVB reception  Time owned: 6 to 12 months
A good clock PROVIDED it can lock to WWVB. When allowed to freerun, it loses as much as a minute a day, and is about as accurate as a Micky Mouse watch.

Too bad the clock oscillators aren't "disciplined" (automatically adjusted for deviation offset). Then it would be a great clock.

I'm operating the clock in a fiberglass sailboat at sea level above salt water. Receiver conditions for WWVB can't be much better than that. WWVB reception here in Northern California isn't wonderful, and it's disconcerting to see a disagreement between UTC and Pacific time on the dual displays, which frequently occurs when only one of the two clocks achieves a time correction.
W6DXK Rating: 5/5 Mar 15, 2009 14:43 Send this review to a friend
Does it all right  Time owned: 0 to 3 months
Just what I wanted - a local and UTC clock that handles DST. Each of the two independent clocks has time zone choice (US) plus UTC and each clock has it's own switch for DST or Standard Time.

Excellent display contrast and the 2" high digits are easy-to-read.

I have it hanging on the wall, but it could also sit on the desk with its built in stand.
W9IQ Rating: 5/5 Dec 26, 2008 08:08 Send this review to a friend
Very Nice  Time owned: 0 to 3 months
I received my MFJ-121B as a Christmas gift from my Dad, N9LOU. I installed the four AA batteries, set the time zones, pressed the SET buttons to synchronize to WWVB and in a few minutes both displays snapped to the correct time including the displayed synchronized seconds. My clock was on the shelf and ready for use in less than five minutes showing Central time in AM/PM format on the upper display and UTC in 24 hour format on the lower display.

The clock has a nice, stylish silver frame that can be wall hung or supported by its rear foldout leg. The control panels are on the rear of the clock. The large digits have a very wide viewing angle and their size make it easy to read it from across the room with low ambient room light. The digits are all full width and well proportioned.

The clock allows both displays to be set to any time zone. The primary US time zones and UTC are selectable by cycling through the icons on the front of the clock. All other time zones can be manually selected. Each display can be set for daylight savings time as well as 12 (AM/PM) or 24 hour mode.

The displays show a blinking satellite (hmm…) icons when they are attempting to lock onto WWVB. Once they have synchronized, the icons remains on solid. If no signal is found, the icons are extinguished. In this case, you can manually set the time on the displays. You can also elect to turn off the automatic synchronization.

Two of the batteries are for the clocks and two of the batteries are for backlighting. The clock batteries have a battery low icon on the upper display. You can program the time when the backlighting comes on for one eight hour period or you can manually turn on the backlighting via a rear panel switch. The backlighting appears to be incandescent lamps. There is no battery low icon for the backlight batteries but the lack of backlighting would make the need for a battery change quite apparent.

The MFJ-121B is a very nice addition to my station. Thanks, Dad!

- Glenn W9IQ

K5ADF Rating: 5/5 May 24, 2008 16:07 Send this review to a friend
So far so good  Time owned: 0 to 3 months
I ordered the clock back early last fall. It finally arrived after a query as to whether I still wanted it. It has been in operation a little over two weeks and locked onto the time signal the first day. So far it is keeping excellent time. One is set for CST/CDT and the other for GMT. Both clocks had a DST switch so one is on and the other off. I have it hanging on the wall about three feet from my HF rig and amplifier in my first floor shack. I have not seen any RFI problems. It is easy to read even from a distance. It takes four AA batteries. We will see how long they last. Hopefully this clock has escaped the mighty fine junk legend.
WB5RPU Rating: 5/5 May 24, 2008 00:12 Send this review to a friend
Updated MFJ-121B  Time owned: 0 to 3 months
I just purchased the "New & Improved" MFJ-121"B" clock and apparently MFJ fixed the problems previously reported in these reviews. They now use FOUR AA batteries instead of TWO AAA. 2 AA for the clocks and 2 AA for the added backlight (dim, but usable). They also replaced the black plastic bezzel with a nice brushed aluminum one which is much nicer. They also provide a switch to disable Daylight Savings Time on BOTH clocks. The first one I received from MFJ had one of the clock displays trashed (random LCD segments lit instead of displaying numbers). I called MFJ and they sent an advance replacement with a pre-paid label to return the defective one. Can't beat that for service. It keeps great time and is always RIGHT ON with WWV. Although it's a bit expensive ($79) compared to MFJ's other clocks, you get what you pay for and I'm very happy with it.
Pete, WB5RPU
K8AC Rating: 0/5 Apr 20, 2007 15:44 Send this review to a friend
Avoid  Time owned: more than 12 months
A clock is a simple device - all it needs to do is display the time. My other atomic clocks need NO intervention ever. The designers of this clock apparently never heard of UTC, or didn't consider that a ham might just have one of the two displays set to UTC. As we all know, UTC doesn't change when daylight savings time starts or stops. But, this clock doesn't know that. It's not possible to turn off the daylight savings time feature, so you'll spend time twice a year resetting the thing. If you want an atomic clock that works as it should, look elsewhere.
N0JL Rating: 4/5 May 4, 2006 13:19 Send this review to a friend
DST drives me nuts  Time owned: more than 12 months
Works fine. Loses lock occasionally, but relocks. Change to DST forces me to reset the UTC portion, which also goes to DST.
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