VK3NX





Australian Amateur Radio STation



9cm eme



VK Band Allocation:


In almost all parts of VK, operation above 3400MHz is no longer permitted!


The VK EME band segment is now 3398 - 3400 MHz


VK3NX will operate typically around 3398.1 MHz +/- and work simplex or Rx crossband on 3400


EME 2008 presentation by Peter Blair - G3LTF
The revival of 9cm EME

9cm EME Equipment



- A homebrew transverter based on the Zac Lau no tune design is used as the basis of the system. This provides a low level output to the PA.

- LNA is a DB6NT Preamp with NF of 0.73 dB and a gain of 28.4 dB- Power amp is 2 combined "toshiba" 50 W amps. Homebrew splitters and combiners are used for ~100 W output.

- Feed is a scaled version of the "RA3AQ" optimised septum built out of 0.5mm copper sheet

- LO is a homebrew design that is PLL locked to a GPS derived 10 MHz signal through a "VE1ALQ" PLL board- Initially it was thought that a Rx capability of 3456 MHz would be required, but as it stands all currently active 9cm stations have access to 3400 MHz and as such this is currently used. A 2nd LO has been built with appropriate switching to allow Rx in the 3456 Mhz band.



Station Performance



Sun noise = 11.3dB with SFU = 63

Moon Noise = 0.52 dB @ Apogee

CS / Gnd = 5.0 dB



Dish Feed



The dish feed is a square septum feed with a transition to a round septum and a choke flange to improve dish illumination. It is a scaled version of "RA3AQ's" feed that was optimised for 1296 to feed dishes with f/d of 0.39 - 0.45. The feed was built out of 0.5mm copper sheet and the septum is seam soldered into position.


Dimensions and test data of CP Septum Feed.

Power Amplifier: 2 x Toshiba 55 W modules



The power amplifier uses splitters and combiners etched on "Ultralam 2000 " teflon board. With 100 W carrier for 30 seconds, there is no detectable heating of the board. The amplifers utilise isolators in the output so a standard impedance matching transformer was built for the combiners. Because of the isolators the need for isolation of the combiner ports is somewhat diminished. On the input a wilkinson Splitter is used with provision for an attenuator in each line. This provides an exceptional Port-Port isolation.



Input Splitter (Wilkinson)Output Combiner (Transformer)



The Board file below is for ULTRALAM 2000 ONLY !!!


Board file in EAGLE Format

9cm EME LOGBOOK


Log Book

VK3NX