Hey everyone! If you’re into amateur radio, shortwave listening (SWL), or just exploring the capabilities of your transceiver, you know how frustrating impulse noise can be—those sharp, crackling bursts that drown out signals. In my YouTube video from 2019, I shared a quick real-world demo of just how effective the noise blanker (NB) feature is on the Icom IC-7300.
This short clip (under 5 minutes) captures a moment when I fired up my IC-7300 for some general coverage shortwave listening and ran into heavy impulse noise. I rarely use noise blankers because they can sometimes distort strong signals, but flipping it on here? Total game-changer!
I Was Wrong About This IC 7300 Feature [Noise Blanker]
The iconic front panel of the Icom IC-7300—my go-to rig for both ham operations and SWL.
Here’s what happened
While tuning around the shortwave bands, the receiver was plagued by impulse noise (probably from local electrical interference). It wasn’t even strong enough to show prominently on the waterfall, but it made listening miserable.
- NB Off: Constant crackling over the signal.
- NB On: The impulses disappeared entirely! Plus, the background noise floor dropped, and the signal strength improved noticeably.
Why the extra improvement? The impulses were pumping the AGC (automatic gain control), which reduced overall sensitivity. With the blanker eliminating them, the AGC settled, letting the real signal shine through (jumping to about S6 on the meter).
I also tested noise reduction (NR) at level 5, but it wasn’t ideal—it muffled the audio like a low-pass filter, cutting highs.
My preferred NB settings:
- Level: 50%
- Depth: 5 (tweaked from defaults for my setup)
Example of the noise blanker menu on the IC-7300—adjust level and depth carefully for best results.
Approximate Transcript (with Timestamps)
For easy reference, here’s a cleaned-up transcript of my video:
[0:16] “So I thought I’d do some general coverage receiver listening today, you know, looking around the shortwave band, see what I can find.”
[0:30] “Wow, that’s got a lot of noise on it—impulse noise. Not strong enough to show up on the waterfall here.”
[0:39] “So I tried the noise blanker feature on this—first time I’ve used it… Generally, I don’t like using noise blankers… But here it is.”
[1:06] (Demo: NB off → on) “Wow, that’s quite dramatic. Not only is the impulse sound completely gone, but did you hear the background noise slowly lift up? That means the AGC was picking up on that noise and reducing the receiver sensitivity.”
[1:46] “Now that noise is gone—S6 on my meter right now.”
[2:09] (NR test) “See how that affects this sound… Mmm, not so good… It sounded like it kind of was a low-pass filter? Like all the highs got kind of cutoff.”
[2:43] “So what do I have my noise blanker set to? Level 50%, depth 5…”
[3:20] “Anyway, that is a short video on the noise blanker function on the Icom IC-7300… 73 guys—like and subscribe!”
Why I Love the IC-7300
The IC-7300 remains one of my favorites for its excellent SDR receiver and features like this often-overlooked NB. It’s perfect for tackling real-world QRM from power lines, appliances, or other sources—without always introducing distortion.
A typical ham radio setup with the IC-7300 in action.
If you’re dealing with impulse noise, definitely experiment with the NB—start moderate and tweak!
Thanks for checking out my video and this companion post. If you’ve had similar surprises with your rig’s noise blanker, share in the comments on YouTube. More IC-7300 tips in my playlist. 73! 📻
Views: 74
