First ever 3.4 GHz EME QSO from Finland !

The first ever 3.4 GHz EME QSO from Finland

QSO between OH2AXH and WB5LUA on 05.01.1998

Here is a description of the 3.4 GHz EME rig ( TX/RX side ( 61 kb ) with LNA and transverter ( 55 kb ) side ) I built for use from OH2AXH. The entire rig is located at the feedpoint of the OH2AXH dish.

Our own echoes ( 29 kb )

This is a short and compressed sound file of our own echoes with my rig at the feed of OH2AXH's 6.4 m dish.

WB5LUA off the moon ( 303 kb )

And this is a longer, albeit compressed sound file of Al's echoes off the moon during our historical QSO.

We have a frequency problem here, as the Finnish ham allocation in 3400 to 3408 MHz whilst most of the world is operating on 3456 MHz. Al built a separate transverter for this single QSO ! 9 cm stations are still so rare though that a couple of other active microwave EME'ers are building rigs for this frequency too.

Some features of the equipment and conditions during the QSO:

  • the LNA ( 55 kb ) is a heavily ( 63 kb ) modified 4 GHz TVRO LNB, noise figure estimated at <0.5 dB
  • the transmitter SSPA fed 11 W at the feedhorn flange after coax lines and relay
  • the transverter layout is based on a DB6NT design for 5.7 GHz
  • TX/RX changeover was accomplished with a high isolation microwave relay ( 64 kb )
  • the antenna feedhorn ( 41 kb ) was a drastically modified commercial 4 GHz TVRO horn
  • overall matching at feedhorn: in excess of 20 dB return loss at all polarisations
  • linear polarisation remotely controlled from shack by servo control
  • frequency was constantly monitored with my homebrew secondary frequency standard
  • weather: QNH 988 mb, heavy, but high overcast, light snow before and after QSO !
  • cold sky/ground noise ratio ~4.5 S-units on the overly sensitive IC-970 scale
  • lunar noise measured at approx. 1 dB above background ( dish beamwidth ~1 degree )
  • own echoes peaking one S-unit

    The Sipoo EME Racing Team group consisted of:

  • Pertti Hohtio, OH2AXH, antenna, infrastructure, real estate
  • Heikki Lahtivirta, OH2BSH, operator
  • Harri Leskinen, OH2JMS, mechanics etc.
  • Michael Fletcher, OH2AUE, microwave & RF, rig

    Here is a plot of the block diagram( 73 kb ).