Observation 3024947: GRIFEX (40379)

Regarding Observation 3024947
and https://network.satnogs.org/observations/3024956/

A few months ago I had quite good observations like those:


Then my mini-circuits amplifier failed and I needed to get a new one. I decided to try from gpio labs, which has good reviews here on the forum. I didn’t use the station for about a month.

The new amplifier has impressive results in the FM band but it seems like the whole spectrum is spread out. I thought that it may be a problem of the SW so I upgraded my client, but it remains the same.

My setup is Cross-Yagi, lightning arrester, LNA, USRP-B205-mini. The rotator is Yaesu G-5500.

Did someone see something similar in his observations and knows how to fix it? I have a strong feeling that there is a problem with creating a waterfall.

Do you use the full 40dB gain without attenuator and bandpass filter? It seems that the B205mini is overdriven by strong nearby signals. The preamp gain should be high enough to overcome the losses between antenna and the receiver, but not exceed this by 20 or 40 dB.

That might be actually true because the gain of the LNA is about 35 dB in the UHF band. Also, I scanned half of the band from 10 MHz do 3 GHz, and I have seen some strong signals (even -13 dBm) in the VHF band. I thought that it may put the amplifier to the saturation mode, but I didn’t think about the USRP.

To compare with the previous LNA ZX60-P103LN+ it is more than 10 dB difference on the same frequency. Thanks @norbert, I will try to get attenuator or bandpass filter :).

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