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

Ole Stender Nielsen olstni at mail.tele.dk
Fri Jul 17 18:10:22 EDT 2015


The value of 2.21 Ohms was picked from the drawer, and you may need/want 
to use another value.
In fact, the values of the input RC network should not be critical, but 
the values in the schematic are those I ended with while doing some 
experiments with different loops.
Best regards
Ole

Den 17-07-2015 kl. 10:03 skrev Magnus Danielson:
> Hi Ole,
>
> Many thanks, 2.21 Ohm sounds more reasonable than 2 ZettaOhm (or 2 
> ZO), which is what 2E21 would translate into if it where 2*10^21, so I 
> wanted to make sure there wasn't a typo. :)
>
> Then I know that my values may vary for that part of the design.
>
> Cheers,
> Magnus
>
> On 07/16/2015 09:21 PM, Ole Stender Nielsen wrote:
>> Hi Magnus,
>>
>> The 2E21 is a 2.21 Ohms resistor.
>> The RC network was found useful to ensure loading at higher frequencies.
>> Best regards
>> Ole
>>
>> Den 16-07-2015 kl. 18:27 skrev Magnus Danielson:
>>> Ole,
>>>
>>> What is the value of the "2E21" resistor?
>>> Looks like a typo. 2k?
>>>
>>> Feel inspired to rig up something for my FS700.
>>>
>>> Will wooden frame my TP-cable wired to form a 8 turns times the
>>> cable-turns.
>>>
>>> Cheers,
>>> Magnus
>>>
>>> On 07/16/2015 09:05 AM, Ole Stender Nielsen 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.
>>>>
>>>> For larger distances to the transmitter site, you may need to insert
>>>> additional amplification between the grounded base pre-amplifier 
>>>> and the
>>>> FS700, and that requires that you provide power to the pre-amplifier
>>>> through a bias Tee, and that you load the FS700 input to keep it 
>>>> happy.
>>>> A while after I installed the antenna in the attic, I added additional
>>>> amplification, not due to a low signal level, but because I wanted to
>>>> use the loop antenna for other longwave services too, and that 
>>>> required
>>>> that I had to split out the signal.
>>>>
>>>> Best regards
>>>> Ole
>>>>
>>>> Den 15-07-2015 kl. 18:02 skrev Dr. David Kirkby - Kirkby Microwave 
>>>> Ltd :
>>>>> Does anyone know of the latest firmware for the Stanford Research
>>>>> FS700 Loran-C frequency standard? I know someone who has one with
>>>>> firmware 1.20, but I don't know if there's any later firmware. I
>>>>> recall asking Stanford Research about firmware for the SR620 but got
>>>>> no response, so I don't know if I will have any better luck with the
>>>>> FS700.
>>>>>
>>>>> What's the best sort of antenna for these? I know Stanford sell one,
>>>>> and by the cost of new professional equipment, the $250 is not
>>>>> abnormally high, but I'd rather look at building something if I
>>>>> purchase one of these standards. I did think of using a half-wave
>>>>> dipole, but my garden is just a wee bit  too small.:-)
>>>>>
>>>>> Dave
>>>>>
>>>>>
>>>>>
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