Hello Mal,

I've wound an air-cored loading coil of about 1.3 H
It's on a wooden frame with hexagonal ends (all yacht varnished) and has a mean diameter of 2 feet.
The winding length is 20 inches and it resonates my 40m inverted 'L' at the correct frequency of 8.97 kHz

I've made a VLF exciter which generates the drive frequency and interfaces with the PC's software.
It uses a 2297 kHz crystal divided by 256 and gives a square wave output for the PA FET's.
I can run CW, QRSS or DFCW with 0.05 Hz shift.

For the TX I've modified my existing 200 watt 500 kHz PA and for matching use an ex-UPS transformer.
The PA seems quite efficient into a 2000 - 3000 ohm resistive load.

I have yet to be picked up beyond the boundary of my own garden so would be over the moon if anyone else can detect my signals.

73 Chris
G3XIZ

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From: mal hamilton <[email protected]>
To: [email protected]
Sent: Mon, 22 November, 2010 16:12:15
Subject: LF: Re: VLF Transmissions



Chris

What are u using for a loading coil, amp etc

mal/g3kev

 

----- Original Message -----

From: Chris Osborn

To: LF Group

Sent: Monday, November 22, 2010 3:13 PM

Subject: LF: VLF Transmissions

LF,

I have permission to transmit VLF this evening and details are as follows:-

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DETAILS OF TESTS

 

Loc:         Biggleswade   IO 92 UB 

Time:       Monday 22nd November 2010   20.00 - 22.00 GMT

Freq:        8.9719 kHz

Mode:      QRSS - 10 second dot length / DFCW with 0.05 Hz shift / CW identifier at 5 wpm

Power:     Limited to 20 watts RF output (ERP unknown)

Aer:         40m inverted 'L' at 10 m above ground.


Any reports or comments are welcome.I

Regards,

 

Chris

G3XIZ