SDR Television - My Station
Inside
All this equipment is installed in my computer room, next to the office.
Some people mount on metal, I prefer wood, much easier! So, what do we see here?
- Early ADALM Pluto version A/B modified by Matthias, DD1US to support a 40MHz reference.
- Analog Devices CN0417 RF amplifier, powered by micro-USB, optimized to operate on 2400 MHz with 18dBm maximum output, gain of 20-21dB, an integrated bandpass filter 2400 to 2500Mhz. Powered by 5V directly via a micro-USB jack. RF input and output connector in SMA.
- Leo Bodnar GPS reference.
- USB relay board which switches the power amplifier.
Also you see two USB hubs, one supplying power only, the other connected to the computer. To keep everything cool a nice USB fan which runs at its lowest setting. The RSHTECH USB hub will soon be replaced, I've had two PSUs die, one generated massive HF interference which was only recently found.
Now the power amplifier. This is a PowerBlast™ 300, a compact, highly efficient, solid state power
amplifier that delivers over 250 watts of RF power over the 100MHz BW of ISM 2.45GHz
frequency band.
The amplifier accepts a nominal 22 dBm (160 mW) RF input and provides 33 dB of gain from
2400 MHz to 2500 MHz for continuous wave (CW) and constant envelope input signals. Based
on the latest and more mature LDMOS technology, this high power amplifier achieves drain
efficiency of 60% (final stage) and more than 57% in module level at rated power.
I haven't finished the screening, so it's held in place by two rolls of solder! Cooling comes from a pair of 80mm USB variable speed fans. Temperature does not exceed 35°C.
The power supply is a RUZIZAO 30V 20A Bench Power Supply which runs at 28V. I like this device as it also shows the wattage.
Outside
Here you see:
- 1.4 prime focus dish with ~300kg of ballast.
- POTY feed.
- Bullseye LNB.
- LDF4-50 1/2″ Andrew HELIAX Coaxial Cable, length 10m.
- A plastic plant pot which keeps the rain off (last image only).
I've had problems with the Bullseye LNBs. They are very good with low phase noise, but the two I own have lost their calibration so a G4EML Bullseye Tuner is used to recalibrate. Many thanks to Mike, G0MJW for building this.
Future
In a month or three I'll be using a LibreSDR. Also, I'm hoping to find a Raven 2.4m dish someday, this would give a gain of approximately 3 (4.77 dB) over the 1.4m dish (compare the surface areas).
Summary
So, that's it. The amplifier puts out far more power than I actually need on DATV - typically running 40w output with plenty in reserve, so I have enough for a good 1,000 ksps transmission.
I'm occasionally on the BATC and WW nets, you have been warned!
