I use this one with the supplied wall wart.
https://www.parts-express.com/dayton-audio-dta-1-class-d-ac-dc-battery-powered-mini-amplifier-15-wpc--300-380
I feed spkr audio to line-in on a mixer, then mixer out to the amp which drives
two small Optimus speakers. Amp is behind mixer in my qrz pic. Its about 99%
interference free from my own TX signals. There was a particular freq which I
can't remember now that might have been getting into my audio distribution
system. Part of my HF loop antenna with up to 500w used is about 15 feet above
the shack/amp. I operate HF with up to 700w, and VHF+ with up to 200w.
7 3 Bob
N2SCJ
-----Original Message-----
From: RFI [mailto:rfi-bounces+n2scj-lists=outlook.com@contesting.com] On Behalf
Of KD7JYK DM09
Sent: Monday, October 5, 2020 12:37 PM
To: Tony <73guddx@gmail.com>; Rfi List <rfi@contesting.com>
Subject: Re: [RFI] RFI Clean Audio Amplifiers For Amateur Use?
> I'm looking for an RFI-free audio amplifier that I can use to power
> the external speakers on my SDR transceiver. The PC speakers I've
> tried were very noisy, especially the USB powered speakers from China.
Almost anything from a thrift shop made in the past thirty plus years, that
runs on a wall-wart from 6 to 12 volts. Use a battery, linear transformer
(about a quarter), or clean SMPSU (25 to fifty cents, same thrift stores...).
So long as your local shop isn't in a high rent district, expect to pay no more
than a buck or two for a pair of speakers, or five to ten for a fancy surround
sound system with a sub-woofer, although the sub-woofer will require AC to
drive it, if the rest of the speakers are nice, re-donate it.
I don't know if that's been been mentioned here before, but the portable, and
QRP boys have been doing this since the early 90's when super awesome
free-to-cheap RFI-less PC speakers began flooding the stores, yardsales, and
hamfests. Best of all, most are through-hole, so easy to interface.
Kurt
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