By 13dka

Following up on the article I recently wrote about the MLite-880, I still had a comparison with a reference radio on a proper antenna on my to-do list. I wasn’t in a hurry because I got pretty fascinated with exploring what I can get out of various magmounts on my car with this radio, which is quite a lot and it never gave me the feeling of missing out on something. I was also a bit hung up on the idea of comparing the MLite with the Belka because, you know, same price level and all, but that’s a bit iffy with my little passive splitter and 2 different input impedances.

Then a claim was made on the interwebz that the MLite-880 would be just a mediocre radio that would not stand scrutiny without its outstanding noise reduction, to summarize that in my own words. My experience is obviously very different and it made me curious how much truth could be in this claim. So I just took the ingenious Icom and the mediocre MLite to the dike to slip in a little shootout and then maybe give the loser a Viking funeral on a little raft I improvised out of flotsam and jetsam while making a lot of recordings to give my findings a whiff of evidence.

Both radios were connected to my lazy 10m/33′ monopole antenna via a Diamond SS-500 splitter and 15m double-shielded and common-mode choked coax. Both were recording to their own SD cards, but unfortunately, the recorded audio from the Icom does not represent the live audio off the radio on AM recordings because it records to an SD card with an 8 kHz sample rate, and that limits the audio bandwidth to at best 4 kHz.  The deciding thing to listen to in these recordings is the noise and sometimes the pure existence of a signal, though, and lower bandwidth is almost an advantage in this context.

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Sensitivity Test

Since the question is really the practical sensitivity and, therefore, how dependent this radio is on its noise reduction to get good results, I’ll start with the IBP beacons, which were recorded without NR, of course. To spot and quantify SNR/sensitivity differences you can use the four -10dB stepped (100W, 10W, 1W, 0.1W) dashes the IBP beacons transmit after their callsign.

The most grassrootsy first: OA4B in Peru (10,800km/6,700mi) on the 17m-band. MLite first, then the Icom. Both radios receive the second (10W) dash as faintly as the 100W dash, but with too little SNR left.

5Z4B beacon in Nairobi, Kenya (6,600km/4,100mi with a 3rd dash = 1W!) informing a silent 15m band about the opportunity around sunset. MLite starts again, then the Icom. The latter has the 3rd dash faintly but clearly and the former leaves some more ambiguity about that. Demonstrates again the minuscule difference.

5Z4B again, but on 20m with a 4th dash to count, whether or not the last one is really from 5Z4B or just interference doesn’t matter; what counts is that both radios heard it. The 1W dash was clearly received by both, starting with the MLite.

Here’s one where only the MLite heard an interference, and I’m not sure it imagined it (absolutely unavoidable pun) – VK6RBP in Australia for the 10,000 miles bragging rights.

I think the conclusion here is that we could probably agree on “same ballpark”, right?  I don’t know about you, but imagine my surprised Pikachu face!

The AF SNR difference, which is probably all that counts in sensitivity tests, is within 3dB between the two, not to be confused with RF power decibels (but reflected on the RF side in comparably small amounts). For the interested:I did take day/night variations of the noise floor above 10MHz into consideration, with a decreased noise level around midnight on 21MHz, the MLite still matches the Icom, which is all that counts in this comparison (not absolute measurements) context.

The magic button

Another claim was made about the noise reduction, that it would only work with signals of a certain strength. While it is technically correct that it needs a minimum SNR to improve upon, my experience is that it is effective with almost any remaining SNR, provided the signal is fed into the NR with sufficient levels, and it exceeds all my expectations at that. Here are a few recordings of CHU demonstrating both points:

CHU 14670 kHz in Ottawa (5,800km/3,600mi) in bad enough conditions. The same announcement from the IC-705, then the MLite with NR at ?  of its range. Note how difficult the French announcement at the end of the transmission is for both radios. I will miss that station. The noise, not so much.

This is just the announcement a minute earlier, when the signal dipped below the noise floor. Nothing gets really recovered, but nothing gets lost either, and what’s left stands out more:

However, if you only look at its inability to cheat physics, you could be missing the point of a good noise reduction in this particular “shortwave radio” context. Restoring fidelity, removing masking noises and generally increasing the SNR and thus ease of listening is having a massive impact on how at least I can enjoy programs or conversations and there’s more: After a few decades many of us (particularly 2-way) radioheads have gotten their auditory cortices hardwired to make a connection between noise and signal strength and then pushing this NR button might feel like witchcraft when it makes a bloke driving around on the other side of the globe sound like he’s just passing your local highway intersection.

In the following sound clips you will hear both radios taking turns in 5-second chunks as if I switch forth and back between them, in some of them I will play the same bit of transmission twice, first from the one, then the other radio so you can e.g. make out differences quite precisely. Continue reading →