Elecraft KX2 audio issues

It’s not strictly on-topic, but I hope that the sheer number of KX2 owners in the SOTA community can provide an adequately sized hive mind and constructive advice.

I have two audio problems with the KX2: I can hear faint CW signals better on the internal speaker than while using earphones, my choice fell on Philips TAA1105BK/00 in-ear sports earphones, they have a 16 ohm impedance, a reasonable frequency response and most importantly they’re small and lightweight.

With small signals I often have to max the AF level to 60, which brings the second problem: when switching from CW to SSB the audio levels are not even remotely comparable and I get blasted with painfully loud sound, AGC is engaged and I already tried with the level limiter, but it requires disabling the AGC and it didn’t help.

Apart from that I didn’t mess with audio menus or AGC thresholds, I also own an IC-705 that doesn’t exhibit these two annoying behaviours.

Considering that I enjoy portable chasing and I’d rather avoid bringing additional gear, is there something that I can do?


Hello Carlo, yes I and others have noticed the first problem, weak KX2 CW audio on headphones compared to speaker. I have only observed this as a problem on a few occasions, typically SOTA summits where the background RF noise is very low so that a weak signal would be easily audible over the noise, but the headphone output level on the KX2 is not as strong as I would like.

I haven’t resorted to it yet, but one possible solution would be a headphone amplifier. A couple of decades ago, before I became interested in ham radio, I build a few CMoy and similar amps that fit into Altoids mint tins. Perhaps I’ll put one in with my KX2 kit.



Sounds like my KX2. The headphone output seems very low. If I use my headphones on my QCXminis then you can get the output to rock concert levels. But the same headphones on the KX2 just don’t have any oomph at all. I’d never looked at the circuit before but there’s a TDA7052A audio amp chip driving the speaker whereas the headphones are driven straight from the TLV320 family stereo codec.

Probably an add on audio amp would make all the difference especially for those of us who went to too many rock concerts in our youth.


Not all headphones are the same…

I also have different models and get along quite well with the HAMA Slight OnEar… it has 32 ohms… and costs less than 5 euros

73 Armin


I will bring a pair of BHI next time, but I was hoping to avoid the dork factor.

Eh? What was that?


A TDA7502 chip ordered (£1.75 inc P&P). It’s an 8pin dip in this case and needs a few R and C and we’re in business.

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Even simpler would be to buy a PAM8403 board (in UK but originating in the Middle Kingdom) for even less money. I think your honorary membership of Scotland might be under review :rofl:


I’d need a 5V regulator though for that one. The 7502 runs from up to 18V so it can be driven off the battery as is.

I use cheap Panasonic earbuds with rubber ear pieces with kx2 and they work great. Plenty of volume and they also block out most ambient noise.

Panasonic ErgoFit Wired Earbuds, In-Ear Headphones with Microphone and Call Controller, Ergonomic Custom-Fit Earpieces (S/M/L), 3.5mm Jack for Phones and Laptops - RP-TCM125-K (Black) Amazon.com


I’ll try to find a similar model that is not in-ear, I’d like to maintain a minimum level of awareness of my surroundings.

You could always leave one out. The reason I got the in-ear model, is when I do SOTA in the winter, I use a Bothy Bag to stay warm. If it’s windy, it makes so much noise that you need the kind that block the wind noise. But, I have wondered about bears sneaking up on me. Hasn’t happened yet :slight_smile:

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