To those of you who use the Hal ST-8000 HF modem....I recently had a problem with one of my units retaining the pre-set Mark/Space/Baud Rate memories. After consulting with Mark Prather WB9HFK at Hal it appeared that U12, a NVRAM chip, on the modem board (top board when you remove the top cover; lower left corner of the board) had gone south. The chip is a DS1220Y manufactured by Dallas Semiconductor (now Dallas/Maxim) and is still available. See:http://www.maxim-ic.com/quick_view2.cfm/qv_pk/3126
The chip contains a small lithium backup battery that maintains the data when disconnected from the +5V DC supply pin. Those backup batteries have a useful life of about 10 years and since many of the ST-8000's in the field are now passing that time frame I would imagine many will need to replace that chip to continue working properly. That internal battery does not recharge so the replacement should be immediately operable.
For some reason (dumb one to boot) I didn't get the chip initially from Dallas directly but instead ordered three chips from Jameco (Jameco PN #114260 at $14.35 per chip). When I tried those chips in my ST-8000's I got really weird results, not the least of which was not maintaining the memory data properly. Thankfully I then found Dallas online and in correspondence with their technical folks it appeared that the chips I obtained from Jameco were possibly not true Dallas products, although the tech guy at Jameco assured me that the units were in fact proper after market units. Long story short I ordered three units direct from Dallas and the cost from them was only $7.09 per chip!!! Those chips as you might expect work like a champ. The Jameco chips are being returned to them for a refund.
If you order some of these chips the 200 ms units are sufficient. Additionally, both the ROHS compliant and old "leaded" chips are available -- you'll get the ROHS chip much faster and the order is much easier to process.
Finally, if you replace the DS1220Y be careful with inserting it into the socket as the socket actually has 2 more holes than the number of pins on the chip....check the orientation BEFORE you take the old one out so you put the replacement chip in correctly.
So if your ST-8000 is "losing its memory" the DS1220Y chip may be your problem. Hope this helps.