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
