Genossen!
I just matched the antenna and run some WSPR-2 transmissions on 137.425 kHz.
I'm getting 260 mA antenna current at 10 W RF power. So the overall loss
resistance should be 150 Ohm (the wire has about 30 Ohm). For resonating
i need about 2.5 nF in series to the wire.
So the feed point impedance is Z = 150 Ohm + j450 Ohm, still behaving as
a loop. Quite a comfortable managable impedance. I had to wind an output
transformer on a "RIK20" core (Reichelt!), which works very well. The
secondary number of turns was unknown at the beginning ;-)
Regular transmissions will start in an hour or so.
73, Stefan
Am 08.09.2018 12:07, schrieb Clemens Paul:
Hi Genosse Stefan,
Will someone catch the signal at all? At least i'm already
asking for RX
stations!
I've just resonated my antenna aa inverted L on 137.5kHz (with 502µH)
and wil be ready to receive in WSPR-2 as soon as you start.
73
Clemens
DL4RAJ
-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of DK7FC
Sent: Friday, September 7, 2018 1:49 PM
To: [email protected]
Subject: LF: 137 kHz WSPR-2 on a 900m long ground loop, this weekend
Genosse Roman, LF,
Yesterday i built a small LF PA providing 10 W at 50 Ohm. It
consumes 1
A at 12 VDC. I intend to run an over-night WSPR-2 transmission (20% TX
rate) on saturday night, using the ground loop or earth antenna in
JN39WI. The signal generator is a Raspberry Pi running on a separate 7
Ah lead gel accu. The PA has its own 7 Ah accu. The PA can switch from
2.5 W to 10 W :-)
Will someone catch the signal at all? At least i'm already
asking for RX
stations!
I'll carry some measuring equipment there, like my M0BMU LF tuning
meter, some Cs, a T106-2 and some wire, also a small ferrite core to
build a transformer if necessary.
What could the feed point impedance be? I have no idea! My modified
MFJ-259B covers LF but i expect it will be overloaded with strong
signals on the antenna, so i try to match the antenna with the
transmitter.
More soon :-)
73, Stefan
PS: Oh, i'm also going to connect two anti-parallel LEDs to
the antenna
to see if they shine. It is all a big game for old children!
Am 05.09.2018 23:54, schrieb Roman:
OK Stefan.
Try it to do. may be wonderful results.
Roman
Hello Roman,
Yes maybe i'll build a quick PA tomorrow for LF and will
transmit on LF
for 24 hours, each 10 minutes, WSPR-2. I have no idea at
all how this
antenna performs on 137 kHz. Is it still a loop or rather a
dipole or a
mixture? At least it has about the length of a full size
dipole for 137
kHz. I would TX at 10 W RF power only, so that a small accu
covers some
hours. But i'm not yet sure if i can find the time to do it
tomorrow.
73, Stefan
PS: If the antenna acts as a dipole, then it is beaming to
Russia directly.
Am 05.09.2018 21:42, schrieb Roman:
Congrts, Stefan!
We are follow by your success!
Listen, do you planning to operate 136 kHz, I hear, tell
me pse - do you planing try to TX with that ant on 477 kHz and 160M?
I will be interestin to hear about results.
73!
Roman
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