LF: RE: DF6NM on 8970.002

["Dave G3WCB." <ganymede444@btopenworld.com>]

Hi, Markus, LF,

 

Bentley accoustics produced the "Ionofane"loudspeaker, that used a corona or plasma discharge as a sound source.

 

Perhaps you should consider modulating your carrier with some music, for the amusement of the neighbours? ;-)

 

http://www.radiomuseum.org/r/faneacoust_ionofane_601.html

 

73, dave G3WCB IO91RM

-----Original Message-----
From: owner-rsgb_lf_group@blacksheep.org [mailto:owner-rsgb_lf_group@blacksheep.org]On Behalf Of Markus Vester
Sent: 27 March 2012 22:23
To: rsgb_lf_group@blacksheep.org
Subject: VLF: DF6NM on 8970.002

It's a beautiful night! At 20:25, I have started up a straight carrier on 8970.002 Hz (DHO locked). If all stays well I will leave it on until after sunrise.

 

An interesting observation on the side: In the first few minutes, I drove the amp up to 400 mA antenna current. A little corona became visible near the ends of two of the three topload wires - it wasn't very bright, not unlike 3rd magnitude stars when viewed from the ground 10 m below. But the 9 kHz sound from antenna itself could be heard quite loudly, which is a potential cause for neighbourhood trouble.

 

Then I reduced the drive to 350 mA where the corona disappeared completely. So did the noise, the antenna became absolutely quiet! All that was left was a little noise from the coil in the dustbin on the balcony, and the transformer indoors. Thus the predominant cause for a squeaking antenna must be corona. The fact that it can be heard at 9 rather than 18 kHz demonstrates that the discharge must have an asymmetric dependence on the voltage polarity.

 

At the same time, wideband electrical noise on the nearby LF grabber antenna went down by 20 dB.

 

BTW If you like you can actually read my VLF frequency from an alias line on the LF TA grabber: It is created by the 24th VLF harmonic, intermodulating with DCF 77, thus appearing on 24 x 8970.002 - 77500 = 137780.048 Hz.

 

Best regards,

Markus (DF6NM)