Re: LF: VLF Transmissions - G3XIZ - 12th / 13th February

[Roger Lapthorn <rogerlapthorn@gmail.com>]

The stability of "within a few mHz" could be a problem for those of us using extremely narrow Spectrum Lab settings to dig your signal out if the noise Chris. This is where absolute locking to a GPS source is so valuable as one can screw the bandwidth right down. A few mHz could mean the carrier drifts and is not detected. Still, I'll be looking!

73s

Roger G3XBM

Via my 2.4GHz handheld (iPod Touch 4g)

On 10 Feb 2011, at 20:21, Chris Osborn <g3xiz@yahoo.co.uk> wrote:

LF

Ok chaps so I'll manually cut the carrier and let you know via the reflector the actual times.

The oven controlled crystal oscillator is running all the time and is quite stable - within a few mHz
provided the shack doesn't experience large temperature variations.

The mains transformer is quite efficient at 9 kHz surprisingly.
It's a big unit about 180mm cube.
The major problem with it is the noise it generates . . . I could do with some ear defenders !
I may make a noise-proof box for it.

73 Chris G3XIZ

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From: Markus Vester <markusvester@aol.com>
To: rsgb_lf_group@blacksheep.org
Sent: Thu, 10 February, 2011 19:48:02
Subject: Re: LF: VLF Transmissions - G3XIZ - 12th / 13th February

Hi Chris,

I also think that a carrier interruption may be more suitable than DFCW,
because it's easy to retain the carrier phase phase, such that a narrow FFT
can integrate across the gaps. For this to work, it is necessary to let
oscillator and dividers (!) run through, and apply the keying only to the
amplifier.

Best 73,
Markus (DF6NM)


From: mal hamilton
Sent: Thursday, February 10, 2011 7:00 PM
To: rsgb_lf_group@blacksheep.org
Subject: Re: LF: VLF Transmissions - G3XIZ - 12th / 13th February

Chris
Some sort of ID is necessary. I arranged with OE5ODL to cut carrier for pos
id. A continuous carrier needs regular cuts.
QRS is preferable to DFCW as an ID tool.
also
regular feedback reporting  is also necessary.
g3kev

----- Original Message -----
From: Roger Lapthorn
To: rsgb_lf_group@blacksheep.org
Sent: Thursday, February 10, 2011 5:52 PM
Subject: Re: LF: VLF Transmissions - G3XIZ - 12th / 13th February


Hi Chris,

Very good luck. I'll be looking for you and hoping for success this time.

An email direct and to this group saying when TX starts/ends would be
helpful. Don't suppose you can send QRSS60 or similar to help with ID? Have
passed the word on to Nick G4IKZ as he is closer to you than me and not sure
he subscribes to this list.

73s
Roger G3XBM



On 10 February 2011 14:42, Chris Osborn <g3xiz@yahoo.co.uk> wrote:

LF,

I have had permission to transmit on VLF this coming weekend: 12th and 13th
February.
Weather permitting I shall try again with my balloon-launched aerial,
hopefully about 50m vertical.

The frequency will be

8.976 66 kHz  (i.e. 10.000 MHz / 1114) and is derived from an oven
controlled xtal oscillator.
Hopefully the frequency will be more stable than last time.
If this frequency proves unsuitable I can transmit on 10.000 MHZ / 1112 .
.10.000 MHz / 1116  etc.

I shall send a continuous carrier as and when conditions permit.

My newly built VLF TX is working well and can deliver about 150 watts of RF.
On this occasion I shall be using the original (fairly lossy) loading coil
but am presently making a more efficient one.

All reports will be most welcome.

73
Chris G3XIZ

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