[Yaesu] FT-ONE - memory board. Anyone got one, made one, or want one?

Tue Mar 7 00:22:43 EST 2017

Dear Dr Kirkby

With reference to your article from 2011 copied below, I have an FT-ONE 
with trouble maintaining VFO memories. Your article mentions 10 memories 
for VFO A and 10 for VFO B. It looks to me viewing the radio that there 
are only 10 VFO memories held, and you can approach them from A or B. 
Allows transmit or receive split.

My rig does not show previous frequencies on start-up, even when the 
mains power cable is still connected. Therefore it seems not a problem 
with the battery backup of the RAM board, as the manual says the backups 
are necessary only when the mains cable is disconnected between radio 
usages. New frequencies are easily reached either by the keyboard or 
dial action. Thus to my limited technical understanding the fault 
appears to lie in the RAM board, probably ? in the two IC chips MN1203.

Do you have any further information on the possibilities of replacing 
these chips with an alternative. Or any other advice on the frequency 
memory maintenance problem?

With kind regards, and thanks

Dr Al Donoghue
ZL4QT

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  [Yaesu] FT-ONE - memory board. Anyone got one, made one, or want one?

*Dr. David Kirkby* david.kirkby at onetel.net 
<mailto:yaesu%40mailman.qth.net?Subject=Re:%20%5BYaesu%5D%20FT-ONE%20-%20memory%20board.%20Anyone%20got%20one%2C%20made%20one%2C%0A%20or%20want%20one%3F&In-Reply-To=%3C4DE91E54.3010201%40onetel.net%3E>
/Fri Jun 3 13:48:04 EDT 2011/

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On 06/ 3/11 06:06 PM, Dr. Gerald N. Johnson wrote:
>/I'm too lazy to download the FT-ONE manual to answer my next question. />/So I'll post it here, what memory chips were used and exactly which year />/was the FT-ONE introduced? I have catalogs back before ICs so I can look />/for prices. One could look in ham store catalogs or magazine />/advertisements to see the factory offered options and prices. />//>/Then an important question is how many were sold without the added />/memory and how many are still in use? />//>/It may prove way more profitable to do a whole sale replacement of all />/the miniature aluminum electrolytics that are partly failed having dried />/out, leaked liquid electrolytics eating traces, and having high ESR. Few />/are bad enough to make easy circuit tracing but replacing the entire />/batch should make the radio work much better. />//>/73, Jerry, K0CQ /
The rig came out in 1982 I think.

The chips used on the optional memory board are MN1203, which are 256 bit (64
words by 4 bits) static RAM. Two of them were used for a total of 512 bits.

I must admit, given there are 10 memories for VFO A and 10 for VFO B, I can't
for the life of me work out how all that data can be kept with only 512 bits.

There's a data sheet on the chip here:

http://pdf1.alldatasheet.com/datasheet-pdf/view/158280/PANASONIC/MN1203.html

and the FT-ONE techincal manual has the details on page 3-42 - page 93 of the
PDF at

http://www.g8wrb.org/data/Yaesu/FT-ONE/Yaesu_FT-ONE_technical_manual.pdf

I've not looked in any detail, but it might be possible to replace the two
MN1203s by a single modern device. That would make the board layout quite easy.
If not, and two modern devices have to be used, one would probably need surface
mount to fit them in. I guess for a one-off, getting a couple of the original
chips would not be impossible, but it might be less hassle to use modern chips,
even though one would not use 99% of their capacity.

Apart from the two chips, there's a couple of connectors which make electrical
contact and support the board. There's also a few R's and C's, but nothing much.

As to how many were sold with the board, and how many remain in use I don't
know. I know I have an FT-ONE which does NOT have the board, but that's just a
sample of 1.

Dave, G8WRB

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