Claim of LF DX ZL6QH to VE1ZJ]

[Andre Kesteloot]

Vernall wrote:

> CLAIM OF ZL TO VE1 AMATEUR LF DX
> 20 December 2001
>
> On Saturday 15 December ZL6QH transmitted a low speed frequency shift keyed
> test signal in the 136 kHz band, as a beacon transmission for all hours of
> local darkness.  John VE1ZJ managed to receive and positively identify
> signals from ZL6QH.  The path length from ZL6QH near Wellington to VE1ZJ in
> Sydney, Nova Scotia has been calculated as being 15,645 km.
>
> VE1ZJ received the LF signal using a 10 metre vertical with top loading,
> high impedance pre-amplifier, low pass filter and a TS-850 receiver.  The
> demodulated audio was fed to a computer sound card for filtering and display
> of the signal using Argo software.
>
> Weak signals were first received by VE1ZJ at 0845 UTC, which was some 40
> minutes after ZL sunset at 0806 UTC and some three hours before VE1 sunrise
> at 1150 UTC.  Best reception was from 1045 to 1138 UTC.
>
> Previous best DX for ZL6QH was confirmed reception by Dexter W4DEX two weeks
> earlier, over a distance of 13,633 km.   W4DEX received ZL6QH again but
> generally not as well as the previous time.  In June and September ZL6QH was
> received by VE7SL, when the test frequency was 184.4 kHz, but since then the
> ZL6QH signal has not been received at all, despite operators being ready to
> try for an LF/HF cross-band contact if propagation was satisfactory at the
> time.
>
> The ZL6QH transmitted signal used frequency shift keying, with 0.4 Hz
> frequency shift.  The uniquely coded transmission consisted of repetitive
> sending of QQQQQ. sent as 137.7900, 137.7900, 137.7896, 137.7900 and then a
> gap, with all elements being of 120 seconds (2 minutes) duration.  This
> means sending a single Q takes ten minutes.
>
> The ZL6QH LF signal was generated using a modified TS-850SAT, in SSB mode,
> fed with audio from a lap top PC, using soundcard software developed by
> Steve VK2ZTO.  TS-850 frequency control was by means of a high performance
> TCXO master oscillator.  The low level LF signal from the TS-850 transverter
> port was fed to an external LF power amplifier, and the output power was
> around 500 watts.  The radiated power is estimated to be 4 watts.  The
> antenna was a long wire at the Quartz Hill club station, which is run by the
> Wellington Amateur Radio Club.  The ZL6QH operator was Mike ZL4OL.
>
> The next test from ZL6QH in the 136 kHz band will likely be in mid January.
>
> Bob Vernall ZL2CA
> Organiser of the ZL LF DX tests