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OE1SMC > MFJ 07.08.94 03:32l 47 Lines 1177 Bytes #999 (0) @ EU
BID : OE1XIB16845
Read: GUEST
Subj: mfj1274c
Path: DB0KCP<DB0AAB<DB0PV<DB0WGS<OE3XSR<OE1XAB<OE1XGR<OE1XIB
Sent: 940806/2146 16845@OE1XIB.AUT.EU
hello, dear yl, dear om !
there are some problems, if you are try to use a mfj-1274c
in the hostmode. it seems to be, that this problems are only in
the new c-model, as there is an aditional ram-memory for the
mailbox-usage. also the rs-232 interface is not so fine.
the changes are made easier, as all chips are pluged in
ans not soldered. the changes are made very quick, if you
know, what to do.
the following steps were done:
- replace the original eprom by the same type ( 27c256 )
with wa8ded hostmode software burned in ( i.e. thefirm )
- replace the chip u3, in handbook desribed as lm324
in my case it was in reality a lm348 - insert a tl074cn
( i think, a 064 or 084 will also work )
- remove chip u40 (74hct374), insert a wire bridge from pin 10
( ground ) to pin 16.
by this, the aditional ram cannot be addressed
many thanks to those om's, who give usefull tips:
daniel HB9VBC @ HB9IAP.SROM.CHE.EU,
al WB0YRQ @ NF0N.#NENE.NE.USA.NA
jeff N4ZWQ @ KJ4LQ.#TIDE.VA.USA
if you can use this information, it would be nice, if you send
me a short mail.
best regards from vienna
hans
oe1smc @ oe1xgr.aut.eu
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