Old 1970s divide by 10 prescaler IC - Page 1
Forum section: electronics / rf-microwave

author: KD4CCF
author_rank: Contributor
timestamp: February 09, 2019, 04:08:51 am
content: I have an old (1978-ish) frequency counter made by a company DSI that's no longer in business. Actually I have two different models from them a 5500 and 5600A.They both use the same divide-by-ten prescaler IC, a 14 pin "DS1020" operating on 5VDC. The literature indicates 10-15mv @ 50-250MHz and 15-50mv 250-450MHz with performance up to 512MHz.The ink has been scrubbed off the IC so I can't see the Mfg, though I would guess it was Dallas Semiconductor? Additional guessing by me is that the DS1020 may be ECL?They both seem to work for now, but worries me that an accidental overload or other calamity could damage the prescaler.What I'm looking for is if there is a datasheet on the IC? I've looked high and low on the Interwebs and can't seem to come up with anything.See image for pin connections.

author: Stray Electron
author_rank: Super Contributor
timestamp: February 12, 2019, 02:23:41 am
content: I think that is the same prescaler that was used in my very old OptoElectronics FC-50C Frequency Counter. The prescaler IC is missing out of it and several years ago I tried to find one but failed. I can't find where I put the schematics and other material but from what I remember it was an 8 pin DIP package that was a divide by ten. Very few of the prescalers made today will divide by ten and I'm not sure that anyone even makes a DIP package prescaler any more. SOMEWHERE I have the schematic of the FC-50C and I THINK I have the data sheet for the prescaler that it used.

author: Andy Watson
author_rank: Super Contributor
timestamp: February 12, 2019, 03:01:13 am
content: Quote from: KD4CCF on February 09, 2019, 04:08:51 amI think that might predate Dallas. Nataional Semiconductor had a range of prescalers with the prefix DS.... Good luck finding it - you might have to track down a paper copy of the Nat Semi databook.

author: edavid
author_rank: Super Contributor
timestamp: February 12, 2019, 04:57:19 am
content: Don't you think DS means DSI in this case? (As in a custom, or at least house numbered part.)

author: floobydust
author_rank: Super Contributor
timestamp: February 12, 2019, 06:38:42 am
content: I thought it might be a Plessey SP8630, SP8665, SP8668 but all use pin 14 as Vcc and pin 10 as input. Other pins match.https://archive.org/details/Sp8000SeriesHighSpeedDividersHandbookMotorola MECL prescalers are 16-pin, as well as 11C90.

author: Stray Electron
author_rank: Super Contributor
timestamp: February 12, 2019, 05:28:42 pm
content: OK I found this manual for an OptoElectronics model 8000 counter and it uses the same prescaler that my FC did. The prescaler was an 11C90 and here is a data sheet for it. I think that that part was made by other companies as well but compare the pinout of your DS1020 to the data sheet and see if it's the same part. FYI the 11C90 is a 5 volt part. Oh and the OptoElectronics manual has some good recommendations for data sheets and for books and manuals about frequency counters, including a data sheet on the 11C90 fromIntersil.I've zero luck finding an 11C90 that's not counterfeit.http://w5rkl.com/wp-content/uploads/2015/02/Opto-8000-manual-with-schematic-and-parts-list.pdfandhttps://www.digchip.com/datasheets/parts/datasheet/321/11C90-pdf.php

author: tek2232
author_rank: Contributor
timestamp: February 12, 2019, 06:43:52 pm
content: attached shots are all 102* IC's from the IC master data book 1993