Cross Country Wireless Receiver Front End Protection Unit (VLF/HF)
Cross Country Wireless produce a receiver front end protection unit to protect sensitive VLF/HF receivers from high levels of RF from other stations on the same site or large antenna arrays.
It is particularly suitable for multi-station contest groups where receiver damage may occur from high power stations operating in the same frequency band. It is also suitable for SDR receiver owners wanting to run receivers 24/7 unattended as the protection unit will divert electrostatic charges and near lightning surges to ground.
How does it work?
The protection unit has three levels of protection against over-power damage, electrostatic charge on the antenna and nearby lightning surges.
A gas discharge tube rated to take nearby lightning surges of 10 kA is connected across the input socket. An isolation transformer connects between the two sockets. This isolates the output socket from any electrostatic charges on the input socket. If the unit is used as the sole protection device for a receiver we recommend that the M6 terminal and wing nut is connected to a good earth or ground connection so that excess energy can safely flow to ground.
The isolation transformer is designed to saturate with very high RF power levels so that a cascaded diode limiter can limit the output power to a safe level.
The multiple levels of protection are such that if the output of a 150W transmitter is inadvertently applied to the protection unit input it will still protect the receiver.
The latest version (June 2021) now limits the maximum output signal to a level lower than the 10 dBm limit of SDRPlay receivers.
SDRPlay recommend the VLF/HF Receiver Protection Unit for use below 50 MHz with SDRPlay RSP receivers.
The protection unit is housed in a compact polycarbonate box measuring 65 x 60 x 40mm.
The box is rated for 25 years exposure to tropical sunlight as well as being waterproof to IP65 if the connectors and cables are correctly sealed to stop water ingress. We can also add a water resistant breather for outdoor use at a small extra cost if required.
We offer a choice of BNC female, F type female or RCA phono coax connectors with a M6 stainless steel binding post for the ground wire connection.
The VLF/HF unit has a through loss better than 0.5 dB from 50 kHz to 50 MHz.
Specification (latest version June 2021) Return loss: Better than 20 dB (VSWR 1.2 to 1) over the full band
Feed through power (20W input): 8 dBm
Feed through power (150W input): 9 dBm
DC isolation between input and output sockets: Better than 400M ohm at 1000V
VAT will be added during the PayPal transaction for UK customers.
Back to Index