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Anytime there's a boatload of audio gain, there's always the possible of feedback causing a squeal or motorboating. Often with an add-on amplifier, it may be necessary to run that on a separate supply. This doesn't have to be a second battery, though. If there's enough supply voltage available, a low-dropout voltage regulator may work wonders for isolating the two blocks of circuitry. It can be installed to feed either the outboard amplifier or better yet, the Murania circuitry itself.
73- Dave, K1SWL
On Wed, Feb 5, 2020 at 11:00 AM Curt M. <WU3URADIO@...> wrote:
Has anyone made any modifications to make the audio louder? I'm not smart enough to do it but it would be interesting if someone could come up with a small amplifier circuit that could be put between the speaker connections and the speaker to give it more volume. I tried one of these little eBay 1w amplifier boards but there must have been some issues with coupling between the speaker out and the input pf the amplifier board because I just got sort of a squeal. There's probably some type of impedance matching or attenuation that needs done to make something like that work becuase it didn't work for me. My hearing is not the best but I was kind of expecting the volume of this kit top be nearly on par with a typical transistor radio.