LF: Re: [sub9khz] E-field probe performance

[Roger Lapthorn <rogerlapthorn@gmail.com>]

Various preamps and E-field probe schematics at https://sites.google.com/site/sub9khz/antennas . If you know of others suitable for VLF use tell me and I'll add them.

I'm a little puzzled by some of the responses, particularly as both PA0RDT and DK7FC designs are E-field probes then surely a "same height, same ground and PSU conditions" test should be possible with a resulting figure possible for like-for-like noise floor, sensitivity (S/N of Alpha beacons, VLF MSK signals), and by looking for the intensity of the intermod line at 9kHz from broadcast signals in Europe an indication of dynamic range? Has no-one done this test at VLF? If not, it looks like I shall have to do it and "suck it and see".

73s
Roger G3XBM

On 28 March 2012 19:41, <cvest@cox.net> wrote:

 

Hi Jim ,

Where did you locate a schematic of the DK7FC , E-probe ? I would like to have a look at it .

Thanks.

Best 73 ,

Charlie , W5COV

---- James Wagner <ka7ehk@yahoo.com> wrote:
> From just looking at the schematics, the PA0RDT design is much higher bandwidth (pushing 10MHz) than the DK7FC design. That places much higher demand on linearity in the presence of strong in-band signals. How that plays out in real life will depend on circumstances. For example, there is a 5KW (significantly higher ERP) AM station at 550KHz less than 10 miles from my QTH. I don't know that it would cause a problem, but I would be careful. There is also a low-power NDB at 225KHz about 15 miles from my QTH. This one should not cause a problem but both are probably in-band for both receivers.
>
> I do note that DK7FC design has limiting diodes at the input of the receiver. This MIGHT well cause a problem with strong-signal intermodulation. Again, it would depend on local circumstances.
>
> Jim Wagner
> KA7EHK CN84km
>
>
> ________________________________
> From: Roger Lapthorn <rogerlapthorn@gmail.com>
> To: rsgb_lf_group@blacksheep.org; sub9khz@yahoogroups.com
> Sent: Wednesday, March 28, 2012 5:43 AM
> Subject: [sub9khz] E-field probe performance
>
>
>  
> Several of the VLF grabbers are now using Stefan DK7FC's E-field probe (Tel
> Aviv, Ipswich, Iceland etc). I'm wondering if anyone has done a straight
> comparison against the PA0RDT design and measured which is better in terms
> of sensitivity and dynamic range?
>
> 73s
> Roger G3XBM
>
> --
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> http://www.g3xbm.co.uk
> https://sites.google.com/site/sub9khz/
>
> [Non-text portions of this message have been removed]
>
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>

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