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Re: VLF: 8270

To: <[email protected]>
Subject: Re: VLF: 8270
From: "Markus Vester" <[email protected]>
Date: Sat, 11 Jan 2014 18:26:30 +0100
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Bob,
 
it's the same antenna that I use for LF. The mast is a fishing rod on an aluminium telescopic pole, pushed out of an unused chimney. It carries three topload legs (N, W and S), about 42 m wire in total (230 pF). The apex is 20 m AGL or 11 m above the roof, but the effective height is only 9 m (calibrated at 138 kHz). On VLF frequencies this is probably even a bit lower due to increased shunting effect from trees. Assuming heff = 0.8 m, radiation resistance on 8.3 kHz would be 0.08 milliohm. With 60 Watts input, I got 0.3 A and 25 kV rms, and radiated power (EMRP) would be around 7 microwatts.
 
Here's a sketch of the wire layout and the auxiliary H- and E-field receive antennas:
 
One could actually see the antenna in Google Map's slant view, but the imagery may have changed since:
 
Best 73,
Markus

From: Bob Raide
Sent: Saturday, January 11, 2014 5:37 PM
Subject: RE: VLF: 8270

Markus;
What are you using for antenna on 8270?
 

From: [email protected]
To: [email protected]
Date: Sat, 11 Jan 2014 14:28:32 +0100
Subject: RE: VLF: 8270

Hello Markus!
Nice signal here, congratulations!

Lubos, OK2BVG


From: [email protected]
To: [email protected]
CC: [email protected]
Date: Sat, 11 Jan 2014 13:59:58 +0100
Subject: Re: VLF: 8270

Took the carrier off air at 12:48. Looks like a good trace at OK2BVG, and a dash with marginal SNR in Todmorden UK.
 
73, Markus
 

Sent: Saturday, January 11, 2014 11:33 AM
Subject: VLF: 8270

At 10:23 I have started to transmit a straight carrier on 8270.000 Hz, estimated ERP around 14 uW. If all stays well, I'll leave it on for a couple of hours, trying to leave a dash on Lubos' and perhaps Paul's spectrograms.
 
73, Markus (DF6NM)
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