That is true, not many hobbyist can afford yourself 2el.quad on 40mtrs but once you try it you can feel the difference. I was lucky that in our club we had 2el.quad but more like oblong shaped and a

There is that. Nonetheless, external attenuation tends to be more linear than most electronically variable attenuators. That's why I automatically reach for them first. {^_^}

In that case it should all be automagic...

That would be true if there wan't any AGC involved. But we have this:

If your noise floor is as high as -55dBm and a broadcaster is clearly hitting 0dBm, I think you should. You are only using half the dynamic range of the receiver :-)

Why adding an external attenuator? Isn't that a job for the AGC? Or has he run out of AGC attenuation range? Regards, Carlos

Keyword: quiet

Remember, there's an AGC with enough range to cover up to +15 dBm without saturation. Leave the decision to use the right amount of attenuation to the AGC. The problems I see in that screenshot: The

Oh yes you do. If you can connect the antenna and have the noise go up more than about 3dB you have room for attenuation. And any decent transmitting antenna will have room for as much as 20 dB

Simon: i will test this night with 768khz.

For 137MHz reception, the Airspy HF+ might be the bee's knees. Dana K6JQ

From: Ronneil Camara Thank you David. My goal is to be able to build a setup that will allow me to capture full disk of earth from GOES satellite. I read from few blogs the Mini is capable. I hope

Adam, I've never had the good fortune to use such an antenna. But I thought the purpose was to put 40dB on the TX signal, not to overload the RX. It looks to me that the visible station is at 0dBfs.

Ruben, Run the HF+ at 768 kHz bandwidth, look for an even stronger signal higher up in the 41m broadcast band. There is no way the signal at 7.210 is causing problems. Simon Brown, G4ELI

Alan, we do not spend the $10k in antenna mast and antennas to put the 40db attenuator on the receiver! Ruben, welcome to the club :-)..... you need a bandpass filter for each HF band you want to

Ruben, On 40m an attenuator can help with a low dipole. You have about 70dB of antenna noise, your screenshot shows you have less than 60dB headroom. 73 Alan G4ZFQ

Alan....external attenuation?

Great, I’ve been wanting to try SdrDx for a long time. Thanks! ~Tudor

Our other software doesn't measure SNR directly but it is around the same.

Ruben, Look at the noise level, 40dB or more attenuation should be used. 73 Alan G4ZFQ