Mike Dennison, G3XDV
LF Amateur Radio

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I have been active on 136kHz both from home and,occasionally, from West Wales. I was part of the first ever QSO on 73kHz, and held the distance record for a two-way contact on that band for 13 months. The first G to work ON on 136kHz.

Currently use 136kHz most days on CW and QRSS (extremely slow CW).

Location:

See Map

Welwyn Garden City, Hertfordshire.
Postcode AL.
Loc IO91VT.
30km north of London.
VFO and Transmitters:

Synthesizer designed by G0MRF and SM6LKM, and built by G0MRF..

Ex-Decca navigation station 1kW transmitter running about 600W on 136kHz from 54V PSU.

'The First', a commercially manufactured 12V 136kHz Tx capable of 100W. [Available from Nevada Communications in the UK]

Transmit antenna:

Marconi, inverted-L 14m high with three top wires 16m long. Top and bottom inductive loading, tuned against earth stakes. Drawing of the antenna system used from September 99.

I have most of the inductive loading at the top of the mast - about 7mH - with just a 0.5mH variometer at the bottom for tuning. This has been found to increase the efficiency.

Receiver:

G3YXM pre-amp into IC-706 Mk 1. The pre-amp is described on G3YXM's site and is available ready-built from G0MRF (see links page).

Receive antenna:

The Marconi works fine for most purposes.

A 0.8m square loop is used for portable work and when I need to null out local noise. This is made from 40-wire ribbon cable, and the wooden spreaders are foldable to get the antenna easily into a car.

Modes Conventional CW and extremely slow CW (usually 4 second dot period). During 2001 I experimented with receiving the BPSK mode specifically designed for LF, WOLF.
Best DX
on 73kHz
  • Best inband QSO (conventional CW): G3YXM at 133km.
  • Best inband QSO (extremely slow CW): MI0AYZ at 493km.
  • Best QSO crossband to 136kHz (extremely slow CW): HB2ASB at 778km.
  • Best DX (extremely slow CW): received by IK5ZPV at 1199km
Best DX
on 136kHz
  • Best QSO (conventional CW): OH1TN at 1783km.
  • Best QSO (extremely slow CW - QRSS): RU6LA at 2823km
  • Best DX (extremely slow CW - QRSS): received by VE1ZJ at 4427km.
Operating periods: Usually active 0830 - 1200UTC Saturday and Sunday mornings. Can transmit any day and time on request.
Skeds and
reports:
E-mail me (see below)
Operation from Wales:  Follow this link.

Last updated: 3 December 2004

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