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I recently purchased a Yaesu FT-70DR and would like to use an earphone of some sort just to listen. On Yaesu's site, there seem to be only 2 official options:

  1. SSM-57A Earbud speaker mic with PTT (doesn't have very good reviews)
  2. CT-44 Microphone Adapter (2 conductor female mic to single jack)

I'm interested in option 2, but I have no idea what can actually be plugged into it, and I can't seem to find anything helpful online. I'm hoping there is some standard type of earphone that can be used with the CT-44. Any help / description of alternatives would be greatly appreciated.

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    $\begingroup$ Hello, and welcome to this site! :-) $\endgroup$
    – Mike Waters
    Feb 6 at 18:11
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    $\begingroup$ Thank you. Happy to be here $\endgroup$
    – bingles
    Feb 6 at 19:16
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The FT-70DR uses the same microphones as the FT-60, including the SSM-17A that you seem to have missed. The plug looks to be a 3.5 mm TRRS. The FT-60 is a common HT that has been produced for years, and there should be lots of accessories for it. It's not clear if the FT-60 and FT-70DR use dynamic or electret (condenser) microphones, but most radios these days tend to use electret microphones because they're cheaper and work just as well for HTs.

You should be able to find nearly any type of headset or hand microphone you like that is compatible with the FT-60 and FT-70DR on the accessory market. But if you don't like the available accessories then it shouldn't be too difficult to wire up an adapter cable or adapter box to use a headset or microphone with a different plug; such an adapter may need to supply amplification or attenuation, and bias voltage for an electret microphone.

You could also find a microphone or headset that uses the older two-plug standard used by that CT-44 adapter, with one plug 3.5 mm and the other 2.5 mm. I tried to quickly find a diagram for the wiring for that standard for Yaesu radios, but couldn't. I know that other manufacturers (Baofeng comes to mind) use a similar double-plug standard, but there is no agreement between manufacturers for microphone standards, so beware: a microphone that works with a different manufacturer's radio and physically plugs into the CT-44 adapter may not work, and might damage the microphone and/or the radio. Personally I wouldn't bother with that annoying adapter; I'd just find a microphone or headset with a TRRS plug that is made to work with the FT-60 and FT-70DR.

When looking for accessory microphones or headsets, your best bet IMO is to contact a well-known amateur radio equipment retailer. They are likely to sell you something of reasonable quality that will work with your radio. The manufacturer MFJ Enterprises makes a variety of accessories, but they have a reputation for erratic quality. (I have an MFJ speaker/mic that works fine. I have no association with MFJ, except as a customer.) Then there is the army of sellers on eBay, Amazon, Alibaba, etc., which sell at low prices, but buyer beware: there is a lot of out-and-out junk out there on the market, and lots of products that are advertised as being compatible turn out not to be.

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    $\begingroup$ Thanks for pointing me to TRRS. It appears that Yaesu is using a slightly different size jack and the pinout for the TRRS is SPK, Data, Mic, GND due to it supporting a clone feature. This link helped me a lot m0wye.radiouk.com/handsfree.doc I decided to buy a CT-44 adapter since it accounts for these nuances. $\endgroup$
    – bingles
    Feb 21 at 1:15
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    $\begingroup$ Would the down-voter care to explain? $\endgroup$
    – rclocher3
    Feb 25 at 16:50
  • $\begingroup$ I upvoted it, and so did someone else who thought your answer was useful. Although explaining the reason for a downvote is not required, it is suggested because it helps everyone. From ham.stackexchange.com/help/privileges/vote-down: "If something is wrong, please leave a comment or edit the post to correct it." $\endgroup$
    – Mike Waters
    Feb 25 at 18:11
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Going by the pictures (not much other information to go by), it seems the breakout cable has a standard headphone Jack and a smaller plug for the microphone. That seems a standard configuration. I would give your local (or less local) ham shop a call and just ask them.

Or,honestly,i'd prefer to buy the two connectors and solder it myself. If you have no experience soldering it might be a good little project to get started with, or you might be able to ask a fellow ham to do it for you. That way,you know what quality you have and can fix it if it would get damaged/cut/.. . It also allows you to use a longer piece of cable if that would help... Good luck!

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