Весьма занятную дискуссию наблюдал в РСГБ недавно.
Не все там читают, ну и найти потом в переписке занимает много времени.
Вероятно, кому то будет полезно.
Всё вспоминал, где у нас тема сводная по рамочным антеннам- вроде была, но не нашел...
Придется отдельной темой оформить.
The Wellgood is not an exact clone of the pre 2014 Wellbrook loop amplifier. The later ALA1530LN uses a completely different amplifier which has greatly improved performance. The ALA100LN amplifier is usually used with large rectangular wire loops e.g. 8m x 2m. Unless you can make a direct comparison between different loop amplifiers you can only have an opinion which can be wrong. Having directly measured the performance of many loop amplifiers I now use an ALA1530LN loop and an ALA100LN with an enhanced wire loop. At 10Km from Brookman's Park MF transmitting site I don't have any IMD products of significance.
Nearly every other loop amplifier has serious IMD problems at my QTH, one- highly regarded by some- is totally useless, it has a claimed performance that is far above the actual IMD2, IMD3 or Noise Figures yet many Hams think it is a good product and recommend it to others.
Mystery NDB
You can normally find a KiwiSDR close to the NDB concerned at
www.rx.kiwisdr.com If you use a remote Kiwi then right clicking on the frequency of interest brings up a NDB database option. A search of that database revealed that SA is on 474.5KHz, 1KHz modulation from Darlowo Poland 25 W and transmits on request. I seem to remember that SA was one of the NDB's that you would sometimes hear on the 630m band along with BIA.
73, Alan G8LCO
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I can vouch for the v3 wellgood loop amp - using a 1m diameter lmr400 as loop - good performance at mf/lf - I have two
Laurence G4DMA (KL1X)
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I can vouch for the v3 wellgood loop amp - using a 1m diameter lmr400 as loop - good performance at mf/lf - I have two
Laurence G4DMA
From:
rsgb-lf-group@groups.io <
rsgb-lf-group@groups.io> on behalf of David Bowman via groups.io <g0mrf=aol.com@groups.io>
Sent: Friday, October 21, 2022 10:45:42 AM
To:
rsgb-lf-group@groups.io <
rsgb-lf-group@groups.io>
Subject: Re: [rsgb-lf-group] NDB ? ON 473 kHz
A very similar loop at a fraction of the price is the "WELLGOOD" loop by George Smart M1GEO
https://www.george-smart.co.uk/projects/wellgood-loop/FYI. If anyone is building switching amplifiers now, I would highly recommend any 3rd or 4th generation Silicon Carbide FETs.
These are the only products I've seen that actually have a specification for a direct short circuit across a supply.
Just make sure the devices switch off at 0V rather than the earlier generation versions that needed -4V to be completely off.
73
David
=============================
-----Original Message-----
To:
rsgb-lf-group@groups.io <
rsgb-lf-group@groups.io>
Sent: Thu, 20 Oct 2022 23:19
Subject: Re: [rsgb-lf-group] NDB ? ON 473 kHz
A really good antenna for LF is the Wellbrook ALA-100-FN I use mine with 5m hexagonal single turn loop and can hear sub 25W NDBs from the west coast on a decent day (1kHz BW, CW) 2000km away, with my ELAD UNOr SDR. I suspect using ANY sensitive RCVR and an active broadband loop like this (you can use a longer wire in ANY configuration so long as L << 1/4wave) for lower Fs.
Darren
VE4VE
