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
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
