SP8685 IC----- 500Mhz counter

[jgrady]

Looking for one of these to fix Heath counter. It is a 500/512 MHz counter used in many small counters. It seems only to be available from Russia??? now?? 16 pin dip, used in heath IM/SM -2400 counter. Any help sincerely appreciated. John Grady

[haklesup]

Do you know who made the IC? (is it Plessy). Are there any other markings on the device. Put "Obsolete Semiconductors" in a search engine to come up with distributors who specialize in out of production devices. <p>I found it on the ubid.com. They list about a dozen distributors with quantity. Search for your part then click on the cross reference link on the resulting page.<p>No wonder why it's hard to find, it's ECL (Logic low = -1.5V and logic High = -0.8V) Not too many designs use ECL technology anymore.<p>[ April 16, 2003: Message edited by: haklesup ]</p>

[bodgy]

These peoplel have 5 in stock factorydirect.co.uk
If it is of any help I have a 8680A which IIRC is an 850MHz version. Unfortunately it is soldered into a preamp board, as many moons ago I had intended it as a front end for a 1GHz Freq Counter.<p>It was part of a Maplin Electronics kit from the 80's part #GJ31J.<p>If you're interested or think you might be able to wiggle this into the Heathkit counter email me.<p>This board has a 7805, BFY90 pre_amp, 1 green LED one RED plus support passives etc. All on a DS PCB with earth plane.<p>I think one of the LED's is power and the other is signal lock. Somewhere I probably have the original circuit diagram.<p>Colin