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Re: LF: Re: Re: 137 grabbers

To: <[email protected]>
Subject: Re: LF: Re: Re: 137 grabbers
From: Minto Witteveen <[email protected]>
Date: Wed, 17 Aug 2011 21:27:04 +0200
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Mal,
Please enlighten me, what would you like to have changed?
I already have Speclab at QRSS3....
 
73’s Minto pa3bca
 
 
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Ceterum censeo Carthaginem delendam esse
 
Sent: Tuesday, August 16, 2011 20:57
Subject: LF: Re: Re: 137 grabbers
 
Minto
Good grabber but can u set it for QRS3
TNX
de mal/g3kev
 
----- Original Message -----
Sent: Sunday, August 14, 2011 10:33 PM
Subject: LF: Re: 137 grabbers
 

Hi Wolf, Stefan, LF

Interesting… might be worth a try. It is easy to set up, I already have the SA612 employed in my 137 KHz receiver.
So… just a ferrite bar, varco, buffered and amplified using a J310, into my current lowpass filter?..  And then (if and when weather permits, it has been raining here for more than two months) out into the field with a fishing pole, miniwhip, ferrite bar, ft817,laptop, etc etc. I was planning to do that anyway to see what the S/N is there, as a comparison with my QTH.

73’s Minto pa3bca

 
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Ceterum censeo Carthaginem delendam esse
 
Sent: Sunday, August 14, 2011 22:27
Subject: Re: LF: Re: 137 grabbers
 
Ferrite RX antennas.. been there when 136 kHz started.
Not as good as a larger air-core loop, possibly noise caused by the Barkhausen effect or similar effects, nonlinearities, etc.
Also beware the ferrite is a semiconductor so you will need some E-field screening, otherwise the ferrite material will couple noise into the windings. But it's not as bad as this may sound; actually I used a ferrite antenna for reception for some years until I discovered I had to disconnect the ...errr... RF counterpoise from the main antenna from the mains "ground", and only use an earthstake during receive, at DF0WD.

On the other hand, it's compact, relatively light-weight, and (in a resonant configuration) gives a nice preselector.
I remember when I connected a ferrite antenna to a tiny receiver with SA612 "gilbert cell mixer", the first signal I heard was G3KEV calling cq in CW.  Q5 in SSB bandwidth.
Such a receiver is extremely handy to go /p for reception, and compare different sites.

73,
   Wolf DL4YHF.


Am 14.08.2011 21:43, schrieb Minto Witteveen:

I haven’t thought about ferrite RX antenna for LF….My guess is that it is not going to work – not without an external antenna coupled to the ferrite, and then what’s the point?
DCF77 clocks often have trouble locking indoors or in the neighborhood of ‘QRM’ generators like PC’s, and look what power DCF77 is using…
I could be entirely wrong of course…

73’ Minto pa3bca

 
Sent: Sunday, August 14, 2011 20:03
Subject: Re: LF: Re: 137 grabbers
 
<snip>
BTW what do you think about a ferrite RX antenna for LF? Now i'm opening an older discussion i expect ;-)

73, Stefan/DK7FC



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