Hello LFers,
This is a short description of my 500kHz transmitter and antenna.
The driver comprises a DDS3 Hands direct digital synthesiser, which came
in the form of a kit. I bought this some time ago as a driver for 73 and
136kHz and has now been reprogrammed for the 500kHz band.
The transmitter uses a PL519 TV sweep tube (valve) with 380v on the
plate (anode). This is driven by a metal 1632, which is a 12v heater
version of a 6L6. The design of the transmitter is derived from my junk
box and provided me with some nostalgic pleasure.
The antenna comprises a HF quad. The quad and its feeder is used as a
short vertical with a capacity hat and is resonated with a variometer
and matched with a ferrite multi tapped transformer located in the
garden shed at the bottom of the garden.
The antenna has a calculated gain of around -20dBi.
The DDS3 is programmed using DOS via the printer port. In the meantime
all my computers have moved on and the only DOS computer I have left is
an AcerNote 760iC laptop, which I still use for QRSS keying.
Unfortunately it doesn't seem to want to talk the DDS3 via the printer
port. Did some old laptops use different pinouts compared with standard
printer ports?
regards
Peter G3LDO
|
