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I am using a Kenwood TS-130S, which has only a 1-pole jack for the key (it is a 1/4" telephone jack, aka "monoaural", tip and barrel only). I know that I need to have an aftermarket keyer to operate with a two-paddle key, whether I use the two-paddle device in "iambic mode" (with squeeze function), or not.

I want to know whether keyers are able to plug directly into my TS-130S "KEY" jack, or whether I need to make internal connections and/or modifications (and if so, what are the implications of the mods).

I have looked at SKC Keyer see QRP_Guys website, or the Open CW Keyer SourceForge_home-page, or perhaps the Nano Keyer nano-keyer website, or the K3NG keyer [RadioArtisan_homepage], and advice from call sign AC0C about keyers.

To be explicit: I am not asking for a direct recommendation for any of those keyers. I am looking for an answer, preferably based on direct knowledge (not speculation), as to whether the radio connection on those keyers is 1-pole or 2-pole. In other words: Do any of the commonly available keyers ONLY work with radios that came equipped with two-paddle key inputs from the factory? OR, Do all keyers work with radios factory-equipped for straight-key (or Bug) inputs?

I do know that, "back in the Day" when the shift was made from straight-and-bug keys to two-paddle keys, the "Keyer" was invented to generate timed dits, and timed dahs, from one paddle and the other --- and so to allow use with older radios. But modern radios have this circuitry built in, and so wonder why there are still so many choices of Keyers.

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    $\begingroup$ Product recommendation questions are not permitted on this site. Can you please edit your question to be asking about the radio interface alone? It's OK to mention products as examples that raise the question. $\endgroup$
    – Kevin Reid AG6YO
    Oct 27, 2023 at 1:40
  • $\begingroup$ I've edited the question as per my previous comment. $\endgroup$
    – Kevin Reid AG6YO
    Oct 28, 2023 at 18:29
  • $\begingroup$ I have not, did not, ask for a recommendation on a particular brand or model. I did mention those strictly as examples of the types of keyers which may embody the range of functions and features. My edit, today, explicitly states that in case there was ever any doubt (which, it seems, there was for yourself). $\endgroup$
    – Birdman
    Oct 29, 2023 at 1:31
  • $\begingroup$ And for extra, extra clarification: the inquiry is NOT really about my radio and its interface. I know what interface it has: it is a one-pole connection for a straight key or bug, both of which are capable of interrupting one circuit, only. The inquiry really is a matter of 1) Is there any variation of the output across all of these keyers, or, are they ALL just single-pole interrupting devices? and 2) IFF there is a difference in the outputs, which ones belong to which class (because those promoting the various keyers seem to have left that information totally off their data sheets)? $\endgroup$
    – Birdman
    Oct 29, 2023 at 1:38

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In my experience radios are generally keyed by grounding the tip of the key jack. The tip will be pulled high by a resistor inside the radio, to 12 V or maybe 5 V.

Other arrangements are possible; I've heard of the key being connected to the HT in valve transmitters, so you keep your fingers on the insulated knob. Test the voltage on your radio, and that it goes to ground.

For keying from a 3.3 V or 5 V microcontroller, you'd use an open collector transistor, so the logic circuit is insensitive to the exact voltage in the radio.

schematic

simulate this circuit – Schematic created using CircuitLab

This is what you see on the QRP Guys design, except with a MOSFET, which saves them one resistor and a few mA:
enter image description here
I'd expect this is the way all keyer outputs work.

For connecting a computer to the radio PTT, I've also used any old opto-isolator, which is probably better practice if you're connecting digital things to an old radio. Both to reduce the amount of RF noise from the keyer and its power supply, and to isolate the keyer from the transmitted RF that may be present on the radio chassis.

schematic

simulate this circuit

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