[time-nuts] Firmware and antenna for Stanford Research FS700 Loran C frequency standard

Attila Kinali attila at kinali.ch
Fri Jul 17 20:20:46 EDT 2015


On Fri, 17 Jul 2015 21:49:01 +0100
"Dr. David Kirkby (Kirkby Microwave Ltd)" <drkirkby at kirkbymicrowave.co.uk> wrote:

> A couple of questions
> 
> 1) Do you have any suggestions for a replacement for the LM394CN, which is
> obsolete and unobtainable from any reputable source? There are plenty on
> eBay for a few $'s from China, but the probability of them being fakes is
> greater than 0.99. The MAT12 seems to be one possible candidate for a
> replacement and while not cheap, is available from reputable sources like
> Farnell.

The SSM2212 seems to be a quite compatible replamcement, with most
parameters being in the same range. Cost ~6USD/pcs

But i guess, for this application, the noise performance of the
transistors is not that critical and something like a BCM847 should
do the job as well. (cost <0.5USD/pcs)

 
> 2) What is the "Ca. 3 Ohm" to the left of your circuit? 

ca. = circa = approximately. Probably an abrevation that is only
common around europe.

> Is that what you
> estimate the input impedance is? I've got 95 m of 2.5 mm^2 wire. The
> resistance of that is about 7.41 mOhm/m so my 95 m would have a DC
> resistance of around  7 Ohms if I used it all.

Hmm.. I think the impedance matters more than the resistance.
But the schematics does not make any reference to that.
Consider me confused. 


			Attila Kinali

-- 
I must not become metastable. 
Metastability is the mind-killer.
Metastability is the little-death that brings total obliteration.
I will face my metastability. 
I will permit it to pass over me and through me. 
And when it has gone past I will turn the inner eye to see its path. 
Where the metastability has gone there will be nothing. Only I will remain.



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