The HF station
The HF station comprises a minimalist approach to the HF bands!
Activity started mainly with the hombrew 10 watt solid state
transceiver (right). When the 5Mhz band was issued, the 7Mhz part
of this rig was modified and it is used mainly on 60m now. The
transceiver is based on the G3TSO Mk 2 design with a 9Mhz IF and makes use of the Plessey
series of SL 600 series of IC's thoughout. A basic 5-5.5Mhz FET
VFO is used in conjunction with a mixer and switched crystal
oscillators to mix to the various HF bands. The output power is
raised to the 10watt level in a solid state amplifier which used
to be marketed in kit form by Cirkit.
The solid state transceiver is complemented by a homebrew VALVE linear (second right) using a pair of 6146's to run about 60W on all bands.
A recently acquired FT-77 transceiver is also used to cover the WARC bands.
The main antenna comprises a 60 foot long, wire doublet used on all bands, with an LDG matching unit, although I'm currently trying out an off-centre fed dipole of the same length.
My current activity is on SSB, WSPR and BPSK. The latter two modes require a high order of frequency stability and a DDS based high stabilty 5MHz external VFO is used both on the homebrew and FT-77 rigs.
I have been listening on the 500khz band using the loop shown below, together with a pre-amp and Lowe HF150 receiver or a homebrew converter which upconverts 500khz to the 144Mhz band.
HF Antennas
Some experiments have been made with a couple of vertical antennas.
The first shown here is a capacitively end loaded vertical diplole covering 40m to 10m with appropriate matching coils at the centre.
Results so far seem to indicate its no worse than my 60 foot long doublet wire antenna and does seem to be quieter. The disadvantage is the need to change the matching coils when a band change is made although with time this could be made automatic.
The second antenna tried is a 1/2 wave vertical for 17m shown here:-
This is made from a telescopic fibre-glass fishing pole, bought on eBay, with a thin wire stretched to the top and a small matching network at the bottom. With the increase in solar flux this antenna has now been re-dimensioned for 28MHz.
JT65 on HF
More recently I have been trying JT65 on 30 ---> 10mm. This seems to work quite well and acivity is on the increase.
I use ~20W into an off-centre feed antenna for 30 --> 15m contacts and a 1/2 wave vertical on 10m, with the W6CQZ software downloaded free on line on a 700Mhz Pentium desk top PC.