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 (60m) 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, off centre fed dipole, used on 80m to 15m , with an LDG matching unit. A quarter wave vertical is used on 10m.
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 here, together with a pre-amp and Lowe HF150 receiver or a homebrew converter which upconverts 500khz to the 144Mhz band. Now it all needs re-tuning to 472KHz!
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 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 was a 1/2 wave vertical for 17m shown here.
This was 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.
JT65 on HF
More recently I have been trying JT65 on 30 ---> 10m. This seems to work quite well and acivity is on the increase.
I use the W6CQZ software downloaded free on line on a 2.4Ghz dual core Pentium desk top Dell Optiplex PC.
mcHF SDR HF Transceiver Project
A recent project has been to homebrew a 5watt HF SDR transceiver from pcbs available on line. It all went together well as can be seen from the photos here, with parts available mainly from Farnell and other on line suppliers. It comprises two pcbs, one containing most of the RF components, the second the display and processor etc.
While it seems to give a good account of itself on receive, connected to a wire dipole, the transmit performance has some spurious issues still to be addressed before it is used in anger on the bands.
An example of it in operation on 60m can be seen here while in test lash-up.
More details on the kit and the radio here