Laurence, Was that Harriman? Cohen? Said? Paschal? A number of folks from that group have published on the AWESOME receiver design over the years, and I have always meant to ask them about the transformer as none of their publications are very specific about the transformer. I’ve wondered about core, bobbin, gauge and layering attributes (re intrawinding and interwinding capacitance) to the extent that those attributes might affect frequency response and signal integrity for the indicated antenna and preamp circuit. I talk with some of those folks regularly so I’ll find out who among them can advise of any transformer materials or winding requirements that are important to noise isolation, signal integrity and response. 73, Jim AA5BW Im presently Beta testing a Stanford VLF standard 5 turn 1 mH 1 ohm 10m sided loop array and a test LNA. Im struggling with data on the transformer which says its primary impedance is 10mH turns ratio of 16 to match the appx 300ohm input Z of the bipolar device. I pinged the author whose phd dissertation it was for actual design material but presently "playing" with a pot core with 10mH primary and 40mH secondary. Anyone have any info as this appears to a standard "transformer" but critical to the LF attributes and sensitivity for the awesome and other penguins designs out there I think in going to be limited on 8kHz due to in ground dog fence pulsing which now way up in level compared with the probe. But the main loop is affixed near 0deg... Ill continuing investigating... After the sequence, the carrier was on 8270.0025 again from 5:25:20 to 8:35. Now QRT. -----Ursprüngliche Mitteilung-----
Von: Markus Vester <[email protected]>
An: rsgb_lf_group <[email protected]>
Verschickt: So, 7 Feb 2016 5:14 am
Betreff: Re: VLF: EbNaut 8270.1 Sunday Just started another sequence with same parameters, running 04:00:02 to 5:25:22 UT. -----Ursprüngliche Mitteilung-----
Von: Markus Vester <[email protected]>
An: rsgb_lf_group <[email protected]>
Verschickt: Sa, 6 Feb 2016 11:52 pm
Betreff: Re: VLF: EbNaut 8270.1 Saturday Thanks once again Paul for your outstanding work. It is great to see what you can make of such a feeble signal, so close to the ultimate SNR limit. Thanks also Lubos and Stefan for continuously running and maintaining your sensitive and useful grabbers. Unfortunately VLF transmissions from here depend on a number of circumstances, and they are not easy to predict and announce beforehand. When I don't have to go to work, and if the wind stays calm, and the weather is dry, and the static background is low, and none of my neighbors complains about the beeps, I might try another one tonight or tomorrow ;-) -----Original Message-----
From: Paul Nicholson <[email protected]>
To: rsgb_lf_group <[email protected]>
Sent: Sat, Feb 6, 2016 1:48 pm
Subject: Re: VLF: EbNaut 8270.1 Saturday > Frequency: 8270.100 Hz,
> start time 9:00:02,
> 5 characters, 8K19A, 16 bit CRC, 10 second symbols,
Decoded 'DF6NM' at Eb/N0 = +0.3 dB, BER 36.5% which
is 67% of capacity.
Carrier 10:25 to 11:25 UT had flux density 0.05 fT
and S/N 11.4 dB using H-field alone. I combined
with E-field to get a couple more dB for the decode.
--
Paul Nicholson
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