The UKRAA Very Low Frequency (VLF) Receiver is designed to record Sudden Ionospheric Disturbance (SIDs) induced by solar flares. It does this by monitoring transmissions from Earth-based beacons, which are affected by changes in the ionosphere, giving an indirect indication of events on the Sun. The main motivation for this work is to correlate the radio observations of solar activity with those from optical observers, and to follow the cycle of sunspots as they appear on the Sun.

The VLF Receiver output is a voltage varying with time, which may be fed to any data logger or digital multimeter. Alternatively, it may be connected to the Starbase software (provided free of licensing charge by UKRAA), allowing observations to be stored centrally and shared with other observers. The VLF Receiver is also compatible with the popular Radio Sky-Pipe data logging software, but extra components will be required.

The VLF Receiver has a tuning range of about 12 kHz to 35 kHz, requires a supply of 15 Volts DC at 35mA, and provides output signals at 0 – 2.5 Volts and 0 – 5 Volts. It is designed to work with the UKRAA VLF loop Aerial and the UKRAA VLF Aerial Tuning Unit. You may also find the UKRAA VLF Signal Generator useful during tuning of the system.

Price: £120.00 Download the order form

The VLF Receiver User Manual is available as a pdf file here

The UKRAA VLF Aerial is designed to receive VLF radio transmissions at suitable frequencies for the UKRAA VLF Receiver. It is used in conjunction with a tuning unit such as the UKRAA Aerial Tuning Unit, to form a ‘parallel tuned circuit’ to provide an input signal to the Receiver in the frequency range 15-35 kHz.

Price: £35.00 Download the order form

The Aerial Kit Assembly Manual is available as a pdf file here.

The VLF Aerial Tuning Unit (ATU) is designed to provide a means of tuning a VLF loop aerial over a wide range (50 pF to 3500 pF) of capacitance. The ATU use a switchable bank of fixed value capacitors and a variable tuning capacitor.
When used in conjunction with the UKRAA VLF Aerial, it will form a ‘parallel tuned circuit’ to provide an input signal to the VLF Receiver in the frequency range 15-35 kHz, enabling the latter to receive VLF radio transmissions at suitable frequencies.
The ATU is a passive device and does not require a power supply.

Price: £25.00 Download the order form

The VLF Aerial Tuning Unit Manual is available as a pdf file here.

The VLF Signal Generator provides a local signal source for tuning the VLF Receiver and the loop aerial to the frequency of military transmitter DHO38 which is located at Ramsloh in Germany. This is the strongest VLF signal in the range of the Receiver in the UK, and is at such a range that its signal will normally provide useful ionospheric response in the event of a Solar flare.

Price: £15 Download the order form

The VLF Signal Generator Manual is available as a pdf file here.

This product is designed as a test instrument to be used with the VLF Signal Generator to investigate the directional sensitivity of the VLF Aerial.

Price: £20.00 Download the order form

Mains Power Supply Unit – UKR022

This is a 15V regulated, linear (non-switching) power supply with a 2.5mm centre positive jack plug, suitable for use with the VLF Receiver and other UKRAA products.

Price: £8.50 Download the order form

Coax lead – UKR012

This 1m RG58 cable with BNC Connectors connects the VLF Receiver to the Aerial Tuning Unit. NB it is included with the Aerial Tuning Unit but may be purchased separately.

Price: £4.00 Download the order form

DC extension lead – UKR013

This product connects the ‘DC V out’ socket from the VLF Receiver to the ‘DC V in’ socket on a UKRAA Signal Generator, Controller or Magnetometer.

Price: £5.00 Download the order form

MAX186 A–D converter chip

The MAX186 Analogue to Digital Converter is an optional component which may be fitted to the VLF Receiver if Radio Sky-Pipe compatibility is required.

Price £20.00 Download the order form