IC-706 Audio weirdness – Check for One Big Punch

I picked up a 2nd hand Icom IC-706MKIIG to add to my eclectic collection of gear earlier in the week. The rig is excellent condition and aside from a loose wire on the molex power lead there were no visible problems which one of the best known Icom boxes of tricks there is.

I re-crimped the power cable and plugged into a dummy load and tested transmit on all bands at lower power and all was well until I got to 2m and the audio was horrible. Really harsh with a pulsing buzzing/grinding noise in the background. Worse than that, going back down the bands the fault was apparent on all bands.

After trying a few random things I found the fault was intermittent so I swapped the microphone for another Icom compatible job and the audio returned to the normal smooth Icom defaults, better than when the microphone was working as it happens so into the back of the microphone I dived.

one big punch

One Big Punch board in IC706 hand microphone

Once the back was whipped off the microphone I found a poorly installed ‘One BIG Punch’ W4RT speech processor stuck inside which had a loose earth connection making all the noise if you held it just so.

I’d never heard of the product before but I yanked it out on the basis that Icom probably knew what they were doing. Only difficulty there was having to replace the .33uf SMD capacitor which was removed during the installation of the module.

As luck would have it the W4RT module had a donor capacitor and the repair was complete after some tweezer and squinting at small components soldering action.

Once plugged back into the 706 and tested locally into the dummy load everything seemed to be in order so I connected up to the antenna and promptly worked VP8AIB/100 in the Falklands and BX3AH in Taiwan on 20m SSB barefoot so I’m picking the One BIG Punch wasn’t really needed.

I don’t understand why folks mess with the audio to get ‘more punch’ but in the process make themselves sound like they’re talking through a toilet roll with corks shoved up their nose. Is this really helpful?

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