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

[Alex Pummer]

MAT12 of ADI is good replacement and it is available at Mouser

http://www.mouser.com/Search/Refine.aspx?Keyword=MAT12



On 7/17/2015 1:49 PM, Dr. David Kirkby (Kirkby Microwave Ltd) wrote:
> On 16 July 2015 at 08:05, Ole Stender Nielsen <olstni at mail.tele.dk> wrote:
>
>> I use a home-made untuned loop antenna with 4 windings of 2.5 mm2
>> insulated wire on a 80 x 80 cm wooden frame, and with a grounded base
>> pre-amplifier mounted on the antenna frame. A schematic is enclosed for you
>> to copy.
>> The pre-amplifier is powered through the cable, and loads the FS700 input
>> as required.
>> I live about 290 km from the island of Sylt, and get nice noise margin
>> figures from the FS700, normally about 40 dB, often up to 46 dB.
>>
> 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.
>
> 2) What is the "Ca. 3 Ohm" to the left of your circuit? 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.
>
> I have built the loop 1.0 x 1.2 m. Hopefully that will be ok to receive at
> least one or both of
>
> * Lessay, France, power = 250 kW, distance = 321 km, bearing = 211 degrees.
> * Anthorn, England, power =- 250 kW, distance = 419 km, bearing 331 degrees.
>
> I now need to work out how many turns to put on it.
>
> Dave
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