5.6 GHz

Amateur TV activity on the 6 cm band is increasing due to the availability of cheap modules intended to transmit “First Person Video” (FPV) back from drones to their operators.

Frequency choice

The UK amateur band plan is shown on the RSGB website here: https://thersgb.org/services/bandplans/html/rsgb_band_plan_2017.htm

GB3KM has a licensed input on 5665 MHz and this has been chosen as out primary ATV operating frequency.

The receive and transmit frequencies are set using DIP switches, and most tune to our chosen FM ATV simplex frequency of 5665 MHz. The recommended polarisation is horizontal.

Equipment=

The FPV units are widely advertised on eBay with titles similar to “Tarot 5.8G 600MW Telemetry TX/RX Combo for FPV Image Transmission TL300N” and are available at reasonable prices.

The typical units are very small but have reasonable FM-TV performance with a quoted spec of 600 milliwatts out and receiver sensitivity of -80 dBm. Amplifiers are available to raise the output power to 2 watts or more.

Using dish aerials of 30 – 60 cm (such as a surplus Sky dish), line of sight ranges of 80 km can easily be achieved. P5 (noise free) FM ATV pictures have beenexchanged over an 85 km path using the equipment pictured.

Detail of G8GKQ transceiver setup is shown here and as seen at CAT17 - the presentation is available here.

Availability of the K&L coaxial relay enables Dave to use one antenna. It may be cheaper to use a separate antenna for receive and transmit as shown in the picture below.

Antennae change over relays

The surplus SMA relays often available at rallys are ideal for 5.6 GHz.

Reverse SMA

Be aware that the relays are almost certain to be standard SMA connectors and the 5.6GHz FPV units are reverse SMA. Adapters are available on ebay on other suppliers.

24v relay operation

Most of these relays are often 24v coils - use a switching regulator from ebay as shown below.