old EME station in JN68rl

The equipment is between 15 and 25 years old now. Three big wind storms (1990, 1999 and 2007) nearly damaged the big dish. Although it could be repaired, the parabolic shape of the reflector had suffered a lot. For example I found out by sun noise measurements, that the performance on 23cm is now only as good as a perfect 7m dish.

I did some repairs, and I am QRV with it on 2m. 70cm and 23cm is receive only now. 

I plan to reactivate in on 70cm as well, but as nearly for everybody, time is a problem.

On 23cm my new 7.3m offset dish in JN68mg is performing better!

 

Here you can find some audio samples and signal plots I made long time ago with the big dish.

ANTENNA:

11.2m dish, homebuilt

f/D = 0.41

2m & 70cm : Dual - Dipole - Feed

23cm : W2IMU - feedhorn

Because of feed interaction, the effective diameter on 70cm is 10 meters only.

On 23cm the efficiency is even less because of underillumination.

The gain on this band is equivalent to an optimized 9 meter dish.

Usually I could hear echos on 23cm with as little as 1 Watt at the feed !

Preamps.:

2m : MGF1801

70cm: FHX35 + MGF1302

23cm: FHX35 + FHX35

Power amplifiers : YL1050 on all three bands

Drivers: 1x2C39 on 2m, 2x2C39 on 70&23cm

3 - phase power supply

 

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