[Lowfer] VLF active antenna

[Souchet]

Hi Chris.

Just for telling you that i have build your Complementary Push-Pull 
Amplifier Active Antennas the one with the Complementary Push-Pull Input 
Stage at Fig. 5 and that it work verry well for me, even at 5 farenheit :)

http://www.home.earthlink.net/~christrask/Paper007.html

If i read you correctly the the OIP3 and OIP2 is +44.25dBm and +68.5dBm and 
it can be further improved by way of using higher current devices such as 
the BFQ19 and BFQ149 for the output devices. Have you made the  OIP3 and 
OIP2 mesurement with these BFQxx transistors.
I am on my way to buil an other one and i will probably build it with the 
BFQxx transistor.

Gillis


----- Original Message ----- 
From: "Chris Trask" <christrask at earthlink.net>
To: "Discussion of the Lowfer (US,European,&UK) and MedFer bands" 
<lowfer at mailman.qth.net>; "Discussion of the Lowfer (US, European, &,UK) and 
MedFer bands" <lowfer at mailman.qth.net>
Sent: Thursday, December 16, 2010 8:11 AM
Subject: Re: [Lowfer] VLF active antenna


> >
>>Objective:
>>
>>Construct an active "e-probe" antenna that is sensitive well down into
>>the audio frequencies (1 kHz or so) up to around 30 kHz, that can be
>>fed with a run of 50ohm coax into a receiver located in the shack.
>>
>
>     Here's the design I came up with a couple of years ago:
>
> http://www.home.earthlink.net/~christrask/Paper007.html
>
> http://www.home.earthlink.net/~christrask/Paper005.html
>
>     Using the amplifier of Fig. 5, one fellow changed the coupling 
> capacitors to 1.0uF and got a bandwidth of 10kHz to 200MHz.  I'm working 
> on a similar design that may have better IMD performance.
>
>>
>>It occurred to me that a "natural radio" front end might be a good
>>choice. Here is what I came up with:
>>
>>http://i81.photobucket.com/albums/j231/Goranothos/VLFantenna.jpg
>>
>
>     I'll have to dig out the whistler receiver I was working on years ago 
> and see how far down it will go.  It's a 2-stage tranformer-coupled 
> low-noise push-pull design.
>
>
> Chris Trask
> N7ZWY / WDX3HLB
> Senior Member IEEE
> http://www.home.earthlink.net/~christrask/
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