(& Wideband FM Speech)
|'Skyscan' LNB.||Bob Platts' (G8OZP) 10GHz RX LNB.|
|I modified this LNB according to Bob's instructions in CQ-TV 152 p53. This included changing the puck to a 9.1GHz unit so that a 23cms ATV RX can be used as a tunable IF. The input is for waveguide WG17 so I made a tapered converter to WG16 as seen above.||This LNB comes ready modified for 23cms IF and has been tweaked for best performance in our 3cms band. Mine is for a round waveguide so I made a conversion using WG16 and a 22mm to water tank connector. The antenna is a horn from G6NHG.|
For transmitting I have a collection of Solfan and similar Gunn diode units. I modulate them with the popular Bob Platts' GunnMod 2 unit built from a kit. I have also built an older design by Bob (CQ-TV 141 p21, mods in 152 p52 and the ATV Compendium p84) which is not quite so good (even after the required modification).
Another transmitter that I have built is the DRO (Dielectric Resonance Oscillator) and amplifier unit as described by Bob Platts in CQ-TV 181 p64-68.
|The DRO section and the 2 stage GaSFET amplifier are cut from a surplus Marconi blue or black cap satellite LNB. I built the psu required for the FETS on a small PCB and mounted it all in a diecast box with an SMA connector for the output. I also mounted another Gunnmod2 modulator to the lid of the box. Unfortunately my amplifiers are not working; perhaps one of the FETs are damaged.
For more ideas on using the blue cap LNB look at the CQ-TV 170 p39 article by G4LXC.
|This is a Gunnmod 2 fitted to the lid. Bob recommended that it was modified by an extra Zener diode, 4.7v 1.3W (eg BZX85), to prevent excessive voltage destroying the DRO FET.|