Signal plots, audios and other measurements

Using a new preamplifier (cavity with MGF4919), I measured a good 22.5dB at SFI 107on 23cm, as you can see from the sun noise plot. The sidelobes are very well suppressed.

For recording the plot, I position the antenna to a precalculated position one hour in advance, and then let the earth rotation do its job. The sun passes through the main lobe of the antenna, two hours of recording time means a 30deg position change of the sun.


The same principle was used to record moon noise on 23cm. It is between 0.8 dB and 0.85 dB at perigee.

I can hear my own echoes using 1W power almost every time: 23cm echo with 1W at the feed

Full power is of course better: SSB echo

ON0EME is a very useful beacon: ON0EME CW

Using WSJT echo mode I can reduce power to very low values and still get echos:


HB9Q (10m dish) copied my signal with -25 in JT65C mode when I was transmitting with 200mW!

Receiving the signals of radio sources resulted in a nice 3D - plot of Cygnus A:

I have not yet tested the dish on higher frequencies, but as it is filled with a 6.3mm mesh I expect a good performance up to 6cm.

I was interested if I can use it on 2m as well, although the diameter is smaller than 4 wavelength on this band. So I placed a 3 element quad in the focus, the 23cm horn was looking through the reflector of the quad.
From the simulation with NEC I could expect a gain of 19dBi for the dish.

At home I have a 13 element yagi, NEC simulation of this antenna resulted in 16dBi.
Both antennas are 2km apart from each other, and both are horizontally polarized. I performed measurements during a weekend with high activity and periods without extra noise, so I could switch off all noise blankers.
The MAP65 decodes were 2 to 5 dB better on the dish than on the yagi in the range of -20.
Thus the dish has about the same performance on 144 MHz as a 4 x 8 element yagi group. The difference is not that big, but it is a nice side effect of the dish that you also can play with it on 2m with a small additional amount of hardware.
I guess you can even use a 6m dish with good success on 2m. In this case I am sure that the offset construction is a big advantage.
Sun noise was 1dB lower on 23cm with the additional 2m feed, this is the penalty for having an extra band.

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