This allowed me to start working on a better antenna, loading coils and other accessories which I found I would require in the course of pursuing LF operation.
It must have been around mid 2002 when I discovered the 136 kHz low frequency band and realised the new challenges there. So I set about listening on those frequencies using my Yaesu FT-747GX which has the capability of receiving down to 100 khz. I researched my options on the internet and was soon listening on the band utilising my HF inverted ‘V’ antenna and a suitable home brew receive ATU. The results to me were amazing and I was soon seeking further improvements to my LF set up as I could see that it was far from its best. The FT-747 was OK for normal morse code (CW) and the faster modes of QRSS CW (very slow morse) but dramatically unstable for the longer dot lengths which were used for long distance (DX) communication. My first move was to fit a temperature controlled crystal oscillator (TCXO) in the Yaesu and although a great improvement was still far from satisfactory. A JRC NRD-345 receiver was added to my shack itinerary, it’s frequency range is 10 kHz to 30 MHz, a much smoother and better resolution tuning and the drift after warm up is no more than about 1 Hz maximum in 24 hours making it suitable for all LF modes even during central heating on and off periods. Next was to improve the antenna and build a transmitter.
My first effort was to build the ‘Marathon’ 5 watt 136 kHz transmitter by Steve Rawlings - GW4ALG, this was created using ‘ugly or dead bug’ construction and it did work, of course 5 watts ouput power really was not sufficient to gain any substantial contacts but at least it got me going transmitting on the band. This was followed by building the 300 watt class D transmitter by David Bowman - G0MRF, which is dual crystal VXO frequency controlled. I next added a DDS VFO kit by Trevor Jacobs - KG6CYN, 1 Hz to 40 MHz with 1 Hz resolution.