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Hi Victor,
+232 dB sounds impressive doesn't it
;-)
In reality the level difference is not so large.
DCF77 comes in around 8 mV/m at 160 km distance, inducing an unloaded
voltage of 8 mV on my antenna. Transforming from 17 ohms and loading would make
that 7 mV at 50 ohms (-30 dBm, S9+43). The best signals from CFH were
around 40 dB less than DCF77.
My LF transmitter was delivering about 55 dBm
("S9+128 dB"), and the level difference to CFH is "only" around 125
dB.
Best 73,
Markus (DF6NM)
Sent: Friday, October 25, 2013 6:09 AM
Subject: LF: RE: Diplexer 137 / 74 kHz
Very
nice job Marcus,21 KV is S9+232dB!
73
Victor
This thing amazes me:
As noted a while ago, I have connected a
makeshift diplexer with the LF transmitter and receiver on one port,
and an additional 74.55 kHz receiver to the other.
At the time of writing, I am transmitting on
137.62 kHz, about 300 W making 4.2 A and 21 kV at the antenna. Now on the
other RX, I can still see DCF77 on 77.5 kHz, and even some of CFH 73.6 kHz
from Canada, on the same antenna which is actually
radiating! There is some RX overload reducing sensitivity by some 20 dB,
but the both signals are still there, and not swamped by noise from
the TX or partial discharges.
Best 73,
Markus (DF6NM)
PS2 Just received a mail from Jay saying that he
picked me up in WSPR-15. Should better go about transmitting
again ;-)
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