TX unit and camera options

The RadCom article talked about First Person Video (FPV) transmit and receive units (used predominantly for drones), and these are the essence of the station. So the first thing I did was email the British Amateur TV Club (BATC) – who had written the article - for more information on the units required.

Upon receiving a speedy response, I ordered a couple of TX units from eBay – the units cost around £8.00 each and would be delivered from China. The order was placed (along with RX units, described further down) and they arrived in about 10 days – which was very quick indeed. These first set of units were actually used by Nick, G0HIK, for his system, so I ordered some more – these took over 2 months to arrive, so in the same time I placed an order for an addition 2 units from a UK seller, which costs slightly more, but arrived within a week.

The TX units in question are : TS58285.8GHz 600mW 32 Channels Mini Wireless 2dbm A/V Transmitter Video TX

They offer an output of just 600mw, but this combined with excellent gain on suitable antennas, can make signal acquisition over a distance of 80 miles. The units can be set to a certain frequency (channelised), and the recognised standard for 6cm ATV in the UK is 5665MHz so it was important to ensure this frequency is covered.

These units offer 32 channels covering bands A, B, E and F and have two switching buttons for the band and channel. Conveniently they feature power off memory for last channel and band saving, so once set you don't need to worry about setting the frequency again.

Specifications:

• Video format supported: PAL and NTSC
• Antenna connection: RP-SMA (Reverse Polarity SMA – more on that later)
• Power input: 7 – 24 Volts
• Transmitting power: 600mW
• Supplied antenna gain: 2dbm (the supplied antennas were not used, other to ensure the units worked)
• Working current: 310mA at 12V
• Video bandwidth: 8Mhz
• Audio bandwidth : 6.5Mhz
• Dimension: 23x 25x 7.7mm (excluding antenna)

Frequency range:

FR1 : 5865, 5845, 5825, 5805, 5785, 5765, 5745, 5725 MHz
FR2 : 5733, 5752, 5771, 5790, 5809, 5828, 5847, 5866 MHz
FR3 : 5707, 5685, 5665, 5645, 5885, 5905, 5925, 5945 MHz
FR4 : 5740, 5760, 5780, 5800, 5820, 5840, 5860, 5880 MHz

As mentioned above these units use RP SMA connectors – so an adaptor is required to connect to the panel antenna which has an N type female. A RP SMA Male to N Type Male adaptor was acquired for a few pounds, again from eBay.

The TX unit does get quite hot when transmitting, even for short periods, so a piece of head sink was glued to the back of the unit to help with heat distribution. As nearly all ATV activity takes place outside the cooler surroundings also helps with this. A 12v fan to cool the unit may be added if required.

The TX unit was mounted in a case which allows for direct connection to the panel antenna. The units come with a lead supplied for power, audio, video and ground, making for easy connection. RCA phono sockets were added to allow easy connection of video and audio sources (the ground was added to the video source). As there is no obvious way of knowing if the unit is powered up (there's no LED or anything to indicate if power is on), so a simple LED was added to show that power, and therefore TX, is on.

A power lead comes from the bottom of the case and is plugged into the 12v power distribution unit (described further down).

As RCA phono sockets were added, this allows for different AV devices to be used. For ease and initial testing 2 small 12v cameras were used. Any video camera with a composite source will work and these have also been used.

I already had a 12v car reversing camera in a drawer in the shack so that was used initially and worked well, giving clear video signals. There were a couple of downsides to this camera, one being that it was video only, so no sound was possible and the other was that as it was a 'reversing camera' intended for a car it had red, yellow and green 'marker lines' that were transmitted. Not the end of the world, and certainly fine for testing purposes.

An added bonus was that the camera was waterproof, so ideal for using during winter !

Options for a new 12v camera seemed to be limited, and it always seemed to be a 'compromise' when finding alternatives. Another camera which was used offering the added bonus of sound, but only a black and white video signal. But again, the low cost (about £5.00 a camera) from eBay made it a suitable choice when trying to keep the cost of 'sundries' down.

These little 380 line PAL black and white mini cameras were brand new and feature switching infra red and have sound. The infra red LED's automatically switch on when light levels get low. They have standard AV connectors for audio and video and require a 12v power supply – a must as I wanted to power all the kit from one 12v distribution unit. The main body of the camera is just 35mm x 25mm x 15mm and they are fitted with a 3.6mm lens.

What the black and white video looses, the audio quality from these cameras more than compensates for. As these ATV systems are FM, the audio is just like any other FM signal – loud and clear!

As already mentioned, I use separate antennas for transmit and receive. More details of the antennas is further down, but for TX a 5.8GHz 24dBi 'Gibeon' panel antenna is used – which covers down to 5665MHz with an SWR of 1:1.

I used slightly differed panel antennas for RX and TX simply due to supply issues, and being only able to purchase one of each type – unless I wanted to spend well over £100 per antenna. As it is the antennas came in at a little under £100 for the two – so slightly more than the 'Get on ATV for under £30.00' RadCom had promised!