Nice Loop. I'm planning a somewhat larger one. So far, I only have
the capacitor. 15-250pF @ 45kV.
- Jerry, KF6VB
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On 2024-02-24 02:16, atlasstuff wrote:
Jim,
Thank goodness the interference was gone the next day and has not
returned. I hope it never does. Sounded like one of these horrible
Chinese, switch mode / pulsed chargers for automotive batteries. So,
my loop stayed under the EMC emergency / break glass cover in the
shack - HI!
Please find attached a picture of the loop. It's very simple but very
effective, with deep nulls. Built on a plastic, electric fence post,
to which I also attach my Kenwood TH-F6 HT as detector / receiver, and
designed to be held in one hand while walking about. With no
amplification, the combination is easily sensitive enough to hear
signals and noises. One enhancement I have thought about is something
to resolve the ambiguity of having two nulls per 360-degree of
revolution. In practice, however, I have not found this essential as,
by making an educated guess / walking about awhile, I have been able
to work out which of the two possible directions noises come from.
I keep the loop tuned for the 80-metre band. It comprises three turns
of single-strand, insulated wire at around 270 mm diameter. Tuned with
the parallel combination of around 210 pF, plus the air variable,
which is probably set to 100 pF for mid-band. The pick up loop is one
turn of the same stiff wire at around 100 mm diameter, direct
connected to a short length of coax terminated with an SMA to connect
to the radio.
I commend having one, or similar, to all that try to make HF radio
work in non-ideal environments. Like we used to keep spare fanbelts in
the boots / trunks of our cars as a guarantee that we would never need
them!
Regards,
Mark, G4FPH.
Links:
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[1] /g/DRAKE-RADIO/message/76328
[2] /mt/104243916/243852
[3] /g/DRAKE-RADIO/post
[4] /g/DRAKE-RADIO/editsub/243852
[5] /g/DRAKE-RADIO/leave/12260778/243852/767576506/xyzzy
