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Re: LF: RE: Ferrite broadband (LF-MF) antenna?

To: "[email protected]" <[email protected]>
Subject: Re: LF: RE: Ferrite broadband (LF-MF) antenna?
From: Daniele Tincani <[email protected]>
Date: Fri, 22 Jun 2012 15:35:57 +0100 (BST)
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Hello Victor, thanks for your reply. In fact, now I think I will use the 12AU7 for a hi-Z pre-amp for a whip or a tuned loop (this again is just for playing with that old glassy lady :-)). As for the BD139, I didn't even suspect it could be used in a RF preamp, I tought of it as good for power stages...
73
Daniele IZ5WWB
 

Da: "[email protected]" <[email protected]>
A: [email protected]
Inviato: Venerdì 22 Giugno 2012 16:19
Oggetto: LF: RE: Ferrite broadband (LF-MF) antenna?

Hello Daniele,
 
some months ago I made a broadbanded ferriterod to cope with heavy qrm on the 80 and 160m band.The ferite comes from a submarine and is specified 10KHz to 4 MHZ with a symmetrical feedingcable to a ELK675 or other receiver without a preamp.Since I don't have such a receiver I made a balanced two stage amp with 4x BD139 grounded base.The antenna copes good with the QRM on 80 and 160,it also performs very well on the MW broadcastband.In the range 200-500KHz it is sometimes better than the E-probe,below 200KHz the E-probe wins.IM is no problem but maby the noise of the amp is to high below 200KHz.
The ferriterod is about750X100mm!
I don't think the 12AU7 is a good choice for a low inputimpedance amp...Zinput 2X BD139 is about 3 Ohm.
 
73
GL
Victor
PA3FNY
 
-----Oorspronkelijk bericht-----
Van: [email protected] [mailto:[email protected]]Namens Daniele Tincani
Verzonden: vrijdag 22 juni 2012 9:42
Aan: [email protected]
Onderwerp: LF: Ferrite broadband (LF-MF) antenna?

Hello LF,
 
I apologize to you all for resuming a topic that was already largely debated here. I have seven of those quite known russian surplus ferrite rods (20cm x 1cm) and - just for my fun - I'm planning to spend some time in building an LF-MF antenna with them. I would like to obtain a broadband (untuned) antenna, ideally VLF-LF and/or LF-MF, suitable for outdoor installation, so what I would appreciate some suggestions about is the required low-impedance amplifier, similar to those used in air-core broadband loops, if it does make sense of course. Any ideas? I found an unused 12AU7 in my drawer, could it be effectively chosen as the active device (low voltage) for such amplifier?
Thank you for any feedback
73
Daniele IZ5WWB
 


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