Hi Markus,
Happy to get your email -- it is encouragment for those lamenting a fried
helix! Without a signal, the DF7FC probe and SL gives about -143 dB.
The LHS of SL says 8.27 kHz 3.8 mHz 60s with the config file being used.
It was actally -70 dB at 1 km; at 5.8 it should be -115 dB which will
be easy to detect -- if I can arrive at that distance before the coil
fails.
Transmissions last about 30 mins until the coil arcs over. Work is
underway towards increasing this number.
I chose 8277 to avoid interference with the serious work being done
on 8270!
73
Joe VO1NA
On Mon, 17 Apr 2017, Markus Vester wrote:
Hi Joe,
Then the coil arced.
Welcome to the club! I'd count that as a success: A real VLF amateur should
always be running close to the voltage limit of the antenna and coil! You
probably had around ~ 7 kV at 0.2 A?
-60 dB readings at 1 km
What was the SNR and FFT bandwidth at that point? Scaling by r^-3 from 1 km to
5.8 km, the signal would be expected to drop by 45 dB at the far field boundary.
How long did the transmission last? Maybe it would make sense for Paul to
inspect Mike's data from Forest/Virginia.
Any special reason why you use 8277 rather than 8270 Hz?
Best 73,
Markus
-----Ursprüngliche Mitteilung-----
Von: jcraig <[email protected]>
An: rsgb_lf_group <[email protected]>
Verschickt: So, 16. Apr 2017 23:58
Betreff: Re: LF: 2017-04-16 03:15:13 VO1NA AA PA0RDT JO11TM 0 477
-25Op8_||||||||||||||_~25dB
Hi Roelof, G.. and Group,
The delayed curtain up on the opera was due to VLF tinkering.
There was much excitement when a pc with a properly working
sound card was deployed. Today I resurrected the low 100m aerial
(Happy Easter to all) and fed 30 watts 200ma on 8277 and
got some lovely -60 dB readings at 1 km. Then the coil arced.
A far field detection was almost a certainty up to this point!
OP8 on 479.477 kHz will resume at 2200 tonight. Good luck
to all and keep up the good work with the RTL Roelof and
thanks for the reports Graham.
73
Joe
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