Hi Minto, Wolf, LF,
With a ferrite antenna you don't even need a fishing pole. 1m above
ground must be OK i think. You can go hiking or riding the bike or take
it to the holidays (even at Ryan air ;-) ) and need no extra power
supply! Hmmm....
Another link with an impressive rod: Search for R33-075-1200 at
http://www.amidon.de/contents/de/d649.html
OK it's a little expensive ;-)
But the 20cm pieces for just 6 EUR should be fine for a first try. I
already thought about ordering some :-)
73, Stefan/DK7FC
Am 14.08.2011 23:33, schrieb Minto Witteveen:
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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