[time-nuts] Data collection cycle -- multiple sources to one counter?

Brooke Clarke brooke at pacific.net
Mon Jun 20 18:49:09 EDT 2005

HI David:

A PIN diode is great for switching RF frequencies above the diode's 
lifetime.  But not so good at switching DC coupled signals.

The FET type switches, like the MAX458 are designed for switching DC 
coupled signals.

Have Fun,

Brooke Clarke, N6GCE
w/Java http://www.PRC68.com
w/o Java http://www.pacificsites.com/~brooke/PRC68COM.shtml

David Kirkby wrote:

> Poul-Henning Kamp wrote:
>> Instead of minicircuits I would be looking for video-cross-bar chips.
> Any reason to prefer them over the pin diode or GaAs switches from 
> Minicircuits? I must admit to having no idea how they would compare here.
>> Maxim as a bunch:
>> http://para.maxim-ic.com/compare.asp?Fam=Vid_Mux_Buff&Tree=SwitchMux&HP=SwitchMux.cfm&ln= 
>> A MAX458 8x4 switch would be able to drive two counters which could
>> measure any two of eight sources against each other.
>>     http://pdfserv.maxim-ic.com/en/ds/MAX458-MAX459.pdf
>> There is even an eval board which does most of the job already:
>>     http://pdfserv.maxim-ic.com/en/ds/MAX459EVKIT.pdf
>> As far as I can tell you could drive it from a parallel port
>> with bit-banging.
> One thing to note is that Maxim have a *very* nice policy on samples, 
> which effectively means for experimental purposes, the chips are free.
> Just register on their web site, tick what chips you want (limit of 
> about 6 or 8, no more than two of the same type) and they courier them 
> to the next day. If you need more than a couple of one type, pick a 
> standard and an extended temperature range model, and perhaps a mil spec 
> one too. Or order some more the next day.
> I don't think you can get evaluation boards for nothing, but I have not 
> actually tried.
> In contrast, I've always had to pay for Mincircuits bits, but do happen 
> to have one of their PIN diode switches sitting around.

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