LinkRF - EME and Weak signal communication

DRILNA is based on the concept of a "STOP NF CULT," where the desperate search for the lowest NF value has led to generations of preamplifiers that do little to combat interference because they are not selective enough. In simpler terms, they are broadband and have very poor input return loss. All this because the only thing that has been pursued for decades, with considerable success, is obtaining preamplifiers with the lowest NF value, but at the cost of a poor IRL, excessive bandwidth, and consequently, a very poor IM3 response.

However, this desperate pursuit of the lowest NF value has yielded great results when the EME station was installed in a relatively calm RF environment, something that is now almost nonexistent.

My approach to the problem goes in the opposite direction: maximizing the IM3 response with the highest possible OIP3 value, eliminating bandwidth as much as possible, and using the NF values as a trade-off currency, at least to the point where the trade don't affect the signal-to-noise ratio or if afect is minimal. I've been testing this for several years, and nowadays other stations are starting to use this concept—"painful" for "NF cult" enthusiasts, but convincing and effective for those who try it.

Once you've tried it, you'll never again follow the archaic concept of: "...you shouldn't install anything in front of the preamplifier that increases the IL and consequently the NF value..." WHY? Well, in lower bands, and I'm speaking strictly in bands from 28 MHz to 432 MHz, the sky temperature dominates the noise contribution. So let's use this noise contribution to our advantage. HOW? i will tel you how in the next lines.

By introducing a high-performance bandpass filter in front of the preamplifier—yes, in front of the preamplifier. For this, we must look for a BPF with the lowest possible insertion attenuation, and after years of searching, the best I've found with excellent results are the filters designed by GORAN YU1CF of Antennas-Amplifiers.

Introducing an excellent BPF before the preamplifier intrinsically requires that the preamplifier have a good IRL (Insertion Loss). Otherwise, the BPF won't work correctly because the filter won't "see" 50 ohms but something much weaker. The result will be a detuned filter with increased ripple and ringing, and a poor attenuation response. Unfortunately, all our preamplifiers have a very poor IRL by default, usually around 4 to 8 dB. The best reach 10 or 12 dB, but always in broadband, which is neither helpful nor useful in the RF-contaminated environments we operate in today.

The DRILNA is the answer to this mistaken concept of "NF CULT" where, in order to obtain the lowest NF values, we have created preamplifiers that are unusable in highly RF-contaminated environments.

I want to clarify that I'm not some FET or NF cult guru; I've simply spent 26 years searching for what I consider best for my main projects, like the IQ+ and IQ+PRO. I'm not going to dwell on archaic FET models like the MGF49XX or MGF18XX, or anything that requires a transformation of thousands of ohms at the input to our standard 50 ohms. That's why I've limited myself to MMIC technology, block amplifiers that have a factory-set 50 ohm input/output impedance. I look for the best MMICs in terms of OIP3 and acceptable NF, without falling into the perverse temptation of the last 40 years of focusing solely on NF values at all costs.

This has led me to 3 specific MMICs from QORVO:

- QPL9547

- TQP3M9036

- TQP3M9037

I selected these 3 because their balanced gain, OIP3, and NF values across a spectrum from 50MHz to 6GHz are among the most acceptable.