by buying a stereo encoder ? I guess a stereo encoder has L/R in and a single unbalanced output ?

And in that output is plugged into the rig mono input ? And that has pilot tone and the signal required to produce stereo transmission or have I got this wrong, thx.

If anyone knows a simple guide to it that would be great. As I have a PCS PLL stable non spurious rig that is nice and clean I can give up on the if I can make it stereo by adding a cheap encoder, any stereo is fine I am not fussy for 1/2 watt fun.

FMEnjoyer wrote: ↑Sat Feb 22, 2025 9:49 am
And in that output is plugged into the rig mono input ? And that has pilot tone and the signal required to produce stereo transmission or have I got this wrong, thx.

Yes that's correct but it's a multiplex input (for audio/RDS/stereo) as opposed to just mono input.

....You could always just download some stereo encoder software so save the money, time and hassles. JMPX works well

FMEnjoyer wrote: ↑Sat Feb 22, 2025 9:49 am by buying a stereo encoder ? I guess a stereo encoder has L/R in and a single unbalanced output ?

And in that output is plugged into the rig mono input ? And that has pilot tone and the signal required to produce stereo transmission or have I got this wrong, thx.

If anyone knows a simple guide to it that would be great. As I have a PCS PLL stable non spurious rig that is nice and clean I can give up on the if I can make it stereo by adding a cheap encoder, any stereo is fine I am not fussy for 1/2 watt fun.

That's basically the procedure yes. It's very important to disable the pre emphasis on the transmitter if it has it and the stereo encoders is the last thing in the chain except an RDS encoder if using one.

Software based encoders provide a good option providing the soundcard used can output the necessary 192khz bitrate for generating an MPX encoded output.

Airomate is an old one but it does fantastic software based stereo and rds in one. The daddy of software ones is Breakaway One for professional grade audio processing as used by legal stations across the globe. It's as good as a £40,000 Omnia or Orban hardware unit.

Thanks, I'll go for a £40K Orban then I think.

Seriously though good to know it can be done in software but I quite like the idea of a minijack hanging out of the box strain relieved with cable ties. Have a little ten quid mp3 player. I will have a little look around online and see if I can find something. Thanks for pre emphasis tip, does it mess the pilot up ?

Then I can forget the Chinese stuff and at least be clean even though it will just be for random laffs.

If you leave the pre-emphasis on, you'll get too much 19 kHz pilot and too much "Side" (difference) signal, leading to very noisy, probably distorted and excessively widened stereo.

It's worth remembering that the bandwidth of the stereo multiplex signal is about 4 times the bandwidth of a mono signal, so to achieve the same signal-to-noise ratio, you need to run about 4 times as much power. That's why switching your receiver to mono when receiving a marginal, noisy stereo signal can really clean things up (though you'll be listening in mono).