On several occasions the HBG plot showed an almost instant drop and
return of the signal received here in NC.  These drops didn't look like
propagation events so I emailed the HBG engineer to see if perhaps these
events were transmitter related.  Below is the response I received.

[email protected] wrote:

Sir

Thank you very much for your message. It is a nice to hear that our signals
can be received in North Carolina.

As for the signal drops, I confirm that our transmitter was down for a short
time on both occasions you mention in your mail. Both events were due to bad
weather conditions (strong winds) in the antenna area.

Jan 7   05:57 to 06:22 (UTC) (I'm recording a measurement every 5 minute,
therefore the real downtime might be slightly longer)
Jan 11  06:43 to 07:18 (UTC)

To complete your records: the transmitter was also down at least 2 times for
shorter laps (on Jan 6 around 18:00 UTC and 20:37 UTC (I think they these
failures are also visible on your graph
http://www.w4dex.com/75khz/hbg07jan03.jpg)

Do not hesitate to contact me again if you need further information

Best regards

Gregor Dudle

> -----Ursprüngliche Nachricht-----
> Von:  Dexter McIntyre [SMTP:[email protected]]
> Gesendet am:  11 January 2003 15:47
> An:   [email protected]
> Betreff:      HBG 75 kHz transmitter
>
> Sir,
>
> For the past month I have been monitoring and plotting the signal
> strength of your 75 kHz transmission for LF propagation studies.  I am
> located in North Carolina, USA.  Today, 11 January and on 7 January, I
> saw a sudden drop in signal strength of approximately 15 dB.  Both times
> the signal was down for about half an hour then came back to normal
> level.  I am trying to determine if these were actually propagation
> events or if perhaps there was transmitter maintenance being performed
> during these times.
>
> If you are interested in seeing my plots the current one is available
> at:
>
> http://www.w4dex.com/75khz/hbg.jpg
>
> The dip at approximately 0640 to 0720 on the 11th of January:
>
> http://www.w4dex.com/75khz/hbg11jan03.jpg
>
> The dip at approximately 0550 to 0620 on the 7th of January:
>
> http://www.w4dex.com/75khz/hbg07jan03.jpg
>
> Also a directory of all plots is at:
>
> http://www.w4dex.com/75khz/
>
> Thank you,
> Dexter McIntyre
> Stanfield, NC USA
> http://www.w4dex.com/