Hi Stefan,
First: congratulations with your ferrite success. Very interesting,
I have already dug up some ferrite bars here …
I moved up the frequency range
of my grabber.
73’s Minto pa3bca
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Sent: Wednesday, August 17, 2011 22:39
Subject: Re: LF: Re: Re: 137 grabbers
Minto,
I have a suggestion too: You could move the upper range to display up to
137.785 kHz, just to display the TA spectrum as well. Then you would have
displayed PA0A yesterday in the evening who was transmitting at 137.777
kHz. Below 137.68 there isn't really something going on,
usually. 73, Stefan/DK7FC Am 17.08.2011 21:27, schrieb Minto
Witteveen:
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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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
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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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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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