RE: AW: AW: LF: Re: Mini-Whip

[Laurence KL1X <hellozerohellozero@hotmail.com>]

Optimum for mine for 10KHz and above is the famed 30cm
 
Laurence KL 1 X
presently  XE
 

---

Date: Wed, 24 Mar 2010 22:56:23 +0100
From: schaefer@hst.tu-darmstadt.de
To: rsgb_lf_group@blacksheep.org
Subject: AW: AW: LF: Re: Mini-Whip

Hi Roelof, VLF,

 

Yes, we (and others) arrived there on 137kHz and above. But it is so hard to belive that this is optimal even in the 33km band. Maybe the optimum C is not a function of the frequency, if discussing an optimal SNR.

But you know i am rather a practical instead of a theoretical OM ;-) Therefore i asked if someone has checked this before on VLF. I also know the equivalent circuit of that probe and the FET input, out of Rs and Cs but anyway ;-)

With a stronger input signal and same SNR there could be a benefit to unsensitive receivers as well (as you mentioned) as long as the input stage is not overdriven...

 

Paul, have you a website where your RX equipment is shown? The antenna and it's environment, cables and so on? Maybe the preamt with the LT1028 and so on?

 

73, Stefan

---

Von: owner-rsgb_lf_group@blacksheep.org im Auftrag von Roelof Bakker
Gesendet: Mi 24.03.2010 22:40
An: rsgb_lf_group@blacksheep.org
Betreff: Re: AW: LF: Re: Mini-Whip

Hello Stefan,

Just like you have reported some time ago, I have done tests to establish 
the best SNR for a whip antenna at LF in regard to the minimum length. I 
arrived at the same length as you did at 137 kHz: 30 cm. A longer antenna 
did improve the signal strength, but not the SNR. The capacitive probe is 
equivalent to a 30 cm whip.

I can't see a reason why the SNR should change with frequency, but I will 
test it nevertheless.

73,
Roelof, pa0rdt

---

Hotmail: Trusted email with powerful SPAM protection. Sign up now. =