[Premium-Rx] *** SPAM *** Re: Wellbrook excellence !

[Peter Rovardi]

Rick,
Yes I,ve tried a couple of different loop configurations, including direct 
connection of the ALA100 Magnetic Detector to the driven element on my 2 
element delta loop @55ft (70ft Circumference ).

This proved to work well over most of the HF spectrum, gain being some 6dB 
above the 180m Dipole and about 10dB from 13 to 15 MHZ. (Due to the loop 
resonance probably )
Also giving a reasonable null over most of HF.
VLF was excellent. Very low noise all the way down to 10KHz .However, a 
permanent instalation on the delta loop, would have required a major feeder 
redesign.
.
 The loop I am currently using is a single loop of 32ft with the bottom wire 
about 6 to 10 ft above ground, (Diamond shape ) and is placed about 30ft. 
away from buildings.
I was surprised to see that this smaller loop was as good if not better at 
VLF than the delta loop, quite amazing.

I suppose though, if you could build some form of super  high-Q VLF 
Preselector connected to a multiturn loop, now that may prove very 
interesting.(Currently playing with a Krohn -Hite Variable Dual Filter  LP 
/HP.150Hz - 1.5MHz . Model 3200R )


As regarding the splitter,i,m not sure, as I use the Kiss approach  to feed 
the AEG 1800/3 or  HF1000 as the Raven Reasearch Multicoupler, has to 
switched out at VLF.

Any suggestions?

73,s   Peter     G4HSB.

----- Original Message ----- 
From: "Rick" <vk4krw at bigpond.com>
To: "Peter Rovardi" <peter at rovardi.wanadoo.co.uk>
Sent: Wednesday, November 22, 2006 10:20 AM
Subject: *** SPAM *** Re: [Premium-Rx] Wellbrook excellence !


> Peter,
> It's Rick from Cairns in Australia here and I would like to ask if you 
> would
> offer any comments on the ALA100 loop size you are using to hear VLF.
> I used to use a home made loop which was an 8M x 8M 4 turn loop arranged 
> as
> a diamond shape and supported by 2" electrical conduit. For convenience it
> hung from a larger tree in my backyard and the base was just 2M above the
> ground.
> I attached an aerial rotator to the lowest support pipe and used that as a
> remote nulling facilty.
> My original amplifier used balanced junction FET's driving a bipolar
> impedance transformer to feed signals via a 50 ohm coax run back to the
> house some 30M away.
> At one time I had remote controlled (tuning voltage) and relay switched
> BB102 (?? memory failing) varactors to allow tuning of the loop over a 
> wide
> range (I recall <150Kz to several MHz). The Q exceeded 200 and I think 
> this
> was the cause of the amplifier's final demise when a closeby lightning
> strike induced so much voltage, the FETs and the varactors were all
> destroyed.
> Untuned it operated well past 10KHz which together with the HF1000 made a
> very good VLF receive system.
>
> As I fully intend to buy Wellbrook's product, I would appreciate any input
> you can offer on the length of wire you are using for the aerial and 
> whether
> you have (or have considered) making it into a multi-turn loop to save 
> size,
> wind loading, inertial moment etc........ I also am thinking of the 
> splitter
> (no idea of cost yet, but he is obviously aware on IMD as a problem) to
> allow use of the signal by several receivers.
>
> I had some correcpondence from Andy at Wellbrook............
>
> "Ideally the loop reactance should be in the range 25 to 200 Ohms. A thin
> wire is approx. 1.6uH/m so a 3 turn loop of 33m circumference may be a 
> good
> starting point, I would recommend some experimentation with the loop 
> size."
>
> As you can see a loop of 33M is quite difficult to hide from the family 
> and
> the neighbours, so I am thinking of (say) 4 turns with a 2M x 2M square
> support frame.
>
> Hope to hear from you,
> Rick
>
> ----- Original Message -----
> From: "Peter Rovardi" <peter at rovardi.wanadoo.co.uk>
> To: <premium-rx at ml.skirrow.org>
> Sent: Wednesday, November 22, 2006 10:17 AM
> Subject: Re: [Premium-Rx] Wellbrook excellence !
>
>
>> Its only on the ALA100 that I can  hear a real signal on 11.2 Khz,
>> using the AEG 1800/3, and none of my other  antennas come close.( 80m
>> Dipole, 20m Delta loop )
>>
>> Amazing low noise at only 6ft and great for nulling out what you dont 
>> want
>> to hear.
>>
>> 73,s   Peter     G4HSB
>>
>>
>>
>>
>>
>>
>>
>>
>> ----- Original Message -----
>> From: "Carcia, Francis A HS" <francis.carcia at hs.utc.com>
>> To: <premium-rx at ml.skirrow.org>
>> Sent: Tuesday, November 21, 2006 10:30 PM
>> Subject: Re: [Premium-Rx] Wellbrook excellence !
>>
>>
>> > I've tested the push pull version with 9.5 dB gain biased at 65 ma each
>> > device and the dynamic range is higher than I can measure with my pair
>> > of 8640Bs. I figure at least 110 dB dynamic range.
>> >
>> >
>> > -----Original Message-----
>> > From: premium-rx-bounces at ml.skirrow.org
>> > [mailto:premium-rx-bounces at ml.skirrow.org] On Behalf Of Bjarne Mjelde
>> > Sent: Tuesday, November 21, 2006 5:08 PM
>> > To: premium-rx at ml.skirrow.org
>> > Subject: Re: [Premium-Rx] Wellbrook excellence !
>> >
>> > From what I know, Andy uses a Norton push-pull amp.  A description of a
>> >
>> > similar amp is found on
>> > http://www.kongsfjord.no/dl/Amplifiers/Ultralinear%202N5109%20And%202N30
>> > 53%20Amplifiers.pdf
>> >
>> > Bjarne Mjelde
>> > www.kongsfjord.no
>> > arcticdx.blogspot.com
>> >
>> > Alberto di Bene skrev:
>> >>> Of course, the other great advantage is that the ALA100 is shipped as
>> > a
>> >>> small black box and you locally supply the wire to make it work !  No
>> >>> problems with postage etc.
>> >>>
>> >>>
>> >>
>> >>   I know that I am asking almost the impossible, but does anybody
>> > knows if/where the schematic of that loop amplifier is
>> >> available ? It shouldn't be rocket science, after all, just a well
>> > designed amplifier, with a careful choice of
>> >> components. Something that many could be able to replicate for their
>> > personal use, without infringing any patents...(and
>> >> saving some money)  :-)
>> >>
>> >> 73  Alberto  I2PHD
>> >>
>> >> _______________________________________________
>> >>
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>> >>
>> >>
>> >>
>> >
>> > _______________________________________________
>> >
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>> >
>> > _______________________________________________
>> >
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>> >
>>
>>
>>
>> _______________________________________________
>>
>> Premium-Rx Mailing List
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>
>