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Reviews Categories | Keyers & CW Keyboards | MFJ-492 Menu Driven Memory Keyer Help

Reviews Summary for MFJ-492 Menu Driven Memory Keyer
MFJ-492 Menu Driven Memory Keyer Reviews: 14 Average rating: 3.5/5 MSRP: $109.95
Description: Multi-function memory keyer with buttons to access memories and commands. Expandable to 8000 characters. Optional MFJ-492 Remote Control Box available.
Product is in production.
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ON6AB Rating: 3/5 Dec 23, 2017 02:23 Send this review to a friend
Memory loss update  Time owned: more than 12 months
Like many other, I too was plagued with the memory loss issue and the buzzzzz problem.
I already showed how to invoke a memory loss by pushing a wrong button sequence.
But on top of that, is there a design fault in the MFJ492?
Could that be the reason it constantly loses his memory and goes berserk producing some low tone buzzzz?
Here’s my 2 cents:
When turned OFF, the TIMEC 80C32-12 microcontroller in the MFJ 492 is supposed to keep its memory by means of the Lithium 3v back-up battery.
Now there’s something odd in the circuitry. The 3v from the battery is fed to the microcontroller via a 560 Ohm resistor in series with a diode. The drop over the diode is 0,6V.
According to the data sheet of the TIMEC 80C32-12 micro controller, the minimum voltage on the Vcc pin should be 2,7V!
The voltage on the Vcc pin of the 80C32 in the MFJ492 will be maximum 3v-0,6v-V resistor.
In other words, with a 3V battery and a diode in series, 2,7V can NEVER be reached at the 80C30!
I replaced the 3V lithium by a 3x 1,5V AAA pack, resulting in 3,5V at the Vcc pin and I never had any memory/buzz issues ever again.
Why still a rating of 3/5?
1- You’re supposed to know what you’re doing when buying MFJ stuff.
2- When it works, the MFJ 492 is a marvelous keyer.
ON6AB Rating: 3/5 Oct 13, 2016 08:51 Send this review to a friend
memory loss  Time owned: 0 to 3 months
I think I found why this keyer suddenly loses memory for no apparent reason:

1- Go to menu "D"
2- Push the "F1" button (Serial No. store).
Enter a wrong character => the keyer answers with a buzzzz.
3- Go now to menu "A", press the "F1" button again and all memories are gone!

Sometimes, entering a wrong character for serial nr. is not even needed.

Try it ;-)

Very good keyer, when it works...
IK2RLS Rating: 5/5 Oct 9, 2015 08:41 Send this review to a friend
There is the Big Reset!  Time owned: more than 12 months
I read in the past on another web site that there is another type of reset for the MFJ492, and I report here to you.
At power on, instead of pushing the first button, press all 6 buttons together with the power on.
This seems much more efficient of the commonly known one, and on my keyer it solves the issue with the Bronx cheer.
My unit is vintage as well from 1993, and it worked fine until 2008. Then the Bronx cheer, and I put it into the dust bin. Two years ago I needed it, and after a better surf on the web, I found this solution.
Reading all posts here, I am quite sure that your broken units can be awaken again.
Now my issue is that I shall program again the unit after the power off. I replaced the battery, but I am afraid it is not the root reason. Perhaps one capacitor died and shorts the power wires from the battery. Does anybody have a schematic of the unit?

Saverio, IK2RLS, former IK5RLS
K8CPA Rating: 2/5 Dec 30, 2014 18:04 Send this review to a friend
Works good, just don't shut it off  Time owned: 0 to 3 months
I got one. The 492X version with the extra chip. Sure enough, I shut it off and it lost it's memory. I called MFJ and they sent me a new backup battery and, I put it in. Again, it still lost its memory when I shut it off and went somewhere.

Came back, turned it on and BZZZZ. No memory.

Had to reset it and reprogram it. Might return it after the first of the year to see if I can get one that will hold it's memory. Just want something to use during Field day.

Will post a updated review once I get the new one.

KK4ITN Rating: 0/5 Mar 19, 2013 16:18 Send this review to a friend
Don't Work  Time owned: more than 12 months
When I first got it the unit was fine for 2 months. I replaced the batteries and installed the upgraded ic. When I turn it off for the night it forgets all memory. Now when I turn it on it grawls at me. When I try to reprogram the memory it grawls or gives me ar.Tried to contact by phone NG-try to contact by email it took one week for an answer.They answered my question by telling me to contact tech. dept. E-mailed them3 MONTHS AGO--STILL WAITING!
AB5RM Rating: 5/5 May 13, 2012 07:16 Send this review to a friend
The switches eventually fail  Time owned: more than 12 months
I bought this in 1999, 13 years ago. I have had to replace the most used switches several times and I suspect the next time the board will go and I will need to replace the whole thing, but it worked great for all these years. I installed extra membory I bought at a local supply house for a couple bucks instead of the high price MFJ wanted for the memory chip. When this one dies, and someday it will, I'll buy another one and be happy about it.
W8GND Rating: 4/5 Aug 8, 2011 05:18 Send this review to a friend
Good, but flakey  Time owned: more than 12 months
Like everyone here, it seems, I love this keyer, even though I'm on my 5th one. I don't know why, but they work for about a week, and then all one gets is a Bronx cheer. Cheaper to buy a new one. Still, it's easy to use, and makes sense. I'm now using one from Idiom Press, and it's tricky, but it doen't die. Jerry W8GND
KT8DX Rating: 5/5 Apr 10, 2011 16:05 Send this review to a friend
I like mine  Time owned: more than 12 months
Mine is 1993 vintage or so. Its been mostly reliable - the occasional bronx cheer (very strange) and balky buttons. But - its easy and fast to use, logically laid out, and I find it as useful as my paddle. I added the MFJ-80 and MFJ-78, which gives me remote capability right on my Bencher paddle, and also another set of memory banks.

Its MFJ, its not sexy, and has some eccentricities. But I like it a lot.
W8GND Rating: 3/5 Mar 27, 2011 03:49 Send this review to a friend
MFJ 492 is ok, but dies  Time owned: more than 12 months
Hi -- just a comment. I'm on my fourth
492. They always die on me. I buy my lithium
batteries by the card of 10, but they're never
the problem. The keyer just dies, giving me the
Bronx cheer.Reset doesn't help.

Still, I'm going to otder another one. There is
no keyer with all of its functions. It's the very
devil of a thing to fix, by the way.

Hats off to Mr. MFJ!

Jerry W8GND
VK5SW Rating: 2/5 Oct 15, 2009 13:20 Send this review to a friend
Unreliable  Time owned: more than 12 months
I've had my keyer for a little over a year now and am disappointed with it. During the 12 month period that it was under warranty, I've had to send it back to MFJ twice to be repaired, having to pay for the freight both times. Now that it's out of warranty, it has failed again, for the third time. Not going to bother having it fixed again, will look around for a diffent make of keyer.
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