Hello YLs and OMs,
One thing I learned very early, when I started with QO-100 last year: it’s all about the proper power level!
This resulted in the fact that I today own way more attenuators than amplifiers. You see so many distorted signals on QO-100 where you can see that the amplifiers are driven beyond their linear range. A little attenuator at the right place would be sufficient to adjust the signal.
My latest acquisition is a 60dB 6GHz programmable attenuator called ATT-6000. It is offered by several people on Ebay, for example. On the internet there are a few discussions about this type of equipment, for example on an Amateur Radio Astronomy website: http://cygnusa.blogspot.com/20…at-for-att-6000-step.html. Here, the 31dB-version is discussed.
The ATT-6000 comes with in a machine finished metal housing that looks very well made. The little unit is powered via an USB-cable. This also allows the programming of the device.
Attenuation adjustment range: 0-60dB
Attenuation step: 0.25dB
Max. frequency: 6GHz.
More date can be found on the internet, e.g. on Ebay. Also, some measurement-charts are available, e.g. about the frequency range and the accuracy.
I have put this device directly behind my Pluto. On 2.4GHz, the base attenuation is in the 5dB range. For my applications this is not relevant. What I want to do is to test various modes on QO-100 in order to find out to what level below the beacon level communication is still possible.
Once I adjust my TX output signal to the beacon level I can reduce my output power accordingly. The absolute attenuation seems to be a little bit lower than said. I measured about 4.6 to 4.8 dB per 5dB attenuation step, however, that might be a problem of the accuracy of my measurement setup. The repeatability of each step, however, lays within a few tenth of a dB. The attenuation can be adjusted with the 5 buttons on the housing of the unit.
The ATT-6000 can also be remote controlled. I used a simple terminal program. Once connected, the device is recognized as a Profilic USB to COM adapter. Basic communication characteristics are: 115200 Baud, 8 Bit, 1 Stop-Bit, NoParity.
The attenuation value is sent to the device by the ASCII-string wv0xxxx, whereas xxxx is the value of the attenuation. 1225, for example, represents an attenuation of 12.25dB 8see pictures). I need to find a simple programming language (I am not yet too familiar with all the modern stuff such as Python), the I can make the adjustment of the attenuation even easier.
This attenuation device is definetely somehing I can recommend for the QO-100 operator. It can be used, for example, to find the proper attenuation value between power amplifiers so that the signal quality is improved. Once measured, which value is needed it can then be replaced by a fixed attenuator.
Vy 73
Holger 'Geri', DK8KW
P.S.: Again, I am in no way connected to anyone who offers this device.