PTT not working for Yaesu FT-65 or FT-4X - not a DigiRig problem or DigiRig cable problem

First, I don’t believe there’s a problem with either the Digirig or the genuine Digirig FT-65 cable. When I push “TEST PTT” in WSJT-X, the impedance between the tip and sleeve of the 2.5mm plug drops from 11 k-ohms to 1.76 k-ohms, which looks reasonable to me. All the connections from one end of the cable ring out fine.
However, when I push “TEST PTT” with the plug inserted in either my FT-65 or my FT-4x, neither goes into transmit.
When I disconnect the cable from the Dgirig, but leave it inserted in the radio, there’s no combination of Tip, Sleeve, R1, or R2 that results in shifting the radio into transmit.
This leads me to believe that there’s something with both the FT-65 and the FT-4x that is inhibiting the radios from going into transmit, possibly a configuration setting, but I haven’t found such a setting.
Does anyone have a suggestion?
Thanks, I’m glad to be here!

If the sleeve to ring2 simulated PTT test fails then the likely reason is incomplete insertion of the connector on the transceiver’s side. See if there is any of the molding on the connector bumping against the radio’s body. In some cases removing some of the offending plastic on the cable can resolve the issue.

The very first time I plugged in the cable I experienced that. Since then I’ve been careful, checking to see if that was the case.
Here’s a picture of the plug in the Jack. I don’t see how it could be plugged in further:

Also, I have verified that the DigiRig works great with my FT-891.

I did discover one thing that is different between the microphone plug for the Yaesu hand speaker/microphone and the Digirig FT-65 cable. The Digirig cable has a three conductor plug (tip, ring, and sleeve) whereas the Yaesu cable only uses a two conductor plug. Here’s a picture of both - Yaesu on the left, Digirig on the right:

Digirig’s cable has three conductors but only uses two so no difference there.

See if you notice any mechanical difference (lengths of the pins, size of the molding etc.)

Right, but it shows the center ring disconnected. I wonder if the sleeve of the Digirig plug is contacting the sleeve contact in the radio or if the Ring on the plug is contacting the sleeve contact in the radio. I considered soldering a tiny jumper between the ring and sleeve of the 2.5mm plug but there’s no real space.
Length and diameter wise the they look identical. There’s quite a difference between the location of the insulators.
The tip is longer on the Digirig plug also.

You can check if there is a ground connection by ringing between the shield of the antenna connector and sleeve on Digirig’s side connector with the cable plugged in.

Thanks for your help! 1.3 ohms from the antenna shield to the sleeve on the four conductor plug on the Digirig end of the cable.
9 k ohms to the ring nearest the sleeve. 5 k to the next, and high impedance to the tip.

That sounds ok, you can test the PTT functionality as shown here:

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Thank you, Denis. That’s the video I watched and followed before my first post. I really appreciate your help. Apparently both of my Yaesu radios have the same issue.

73 de AI7KS

I think that what is happening is that the 3 pole 2.5mm plug used on the Digirig cable doesn’t correctly contact the 2 pole jacks used in both my FT-65 and FT-4.
I’ve ordered some 2 pole plugs so I can attempt to wire up a similar cable to see if that works. At times like this I miss Radio Shack. :grin:
I’ll report my results next week.

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Data point: I just got a cable for my FT-65R and the PTT test via WSJT-X does seem to work for me. As far as I can tell the plug on my cable is physically the same as yours.

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Interesting. Is your FT-65 one of the ones made in China or the later ones that were made in Japan? Mine was made in Japan and both my FT-4 and my FT-65 fail to detect the state change.
I see the change in state on the output ring of the Digirig FT-65 cable when I “TEST PTT” or “TUNE” in WSJT-X. Also, shorting the sleeve to the ring on the 4 pole Digirig cable end doesn’t cause PTT, but I opened the case of the external microphone and I am able to short the two wires on the mike cable and it goes into transmit, which leads me to believe there’s just something about the cable.
But, I ordered a two pole cable with tinned ends to test and see if it works.
Thank you for the information.
Steve - AI7KS

My FT-65R is pretty new and made in Japan. I agree it sounds like an issue with the plug to HT connection, or possibly the cable isn’t pulling to ground as hard as it’s supposed to?

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Well, although my experiment had to be truncated, I did have some promising results.
I ordered a four pole plug with a breakout terminal on the other end. I also ordered a two pole 3.5 mm plug with tinned ends and a two pole 2.5 mm plug with tinned ends.
I’ve inserted the tinned ends into the terminal block to match most of the DigiRig connections in the diagram posted by Denis above.
The success I had is that with this configuration I am able to short across two of the connections and see the FT-65 reliably transmit.
I have one more connection to make and I have to insert the 2k resistor in the PTT line (I’m connected directly right now). Then I’ll test it again.

I finished the experiment. I added a 2k resistor in-line between R2 on the four pole end and the tip of the 2.5 mm two pole plug that goes into the mike input of the FT-65 or FT-4.
Also R1 on the four pole plug is connected directly to the tip of the 2.5 mm two pole plug.
Shorting the sleeve to R2 on the four pole plug now puts the radio into transmit on both radios, which didn’t work for either radio before using the three pole plug of the genuine Digirig plug.
Just to be sure I wasn’t missing something when I tested it with the Digirig cable I plugged it back in and shorted it (sleeve to R2) and again nothing happened.
So, my conclusion is that the location of the ring on the coiled Digirig cable is just different enough from the contacts in the jacks on both Yaesu radios that it doesn’t work.
Finally, I connected my Frankenstein cable to the Digirig and my radio and plugged it into the computer and it worked perfectly with WSJT-X, transmitting when commanded using the TEST PTT button, the TUNE button, and when it was appropriate to transmit in FT-8 mode.
Denis, could I possibly get a replacement for the FT-65 cable directly from you or should I go back to Gigaparts?

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@K0TX - what should my next step be?

Apologies for the delay. I can replace the cable but the chances are good that the replacement will have exactly the same issue pairing with your transceiver. If you are unable to return it to GigaParts for refund, you can send it to me for store credit.

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I wondered about that. It’s odd that it works the same for both radios. I wonder if Yaesu changed their jacks at some point. I bought both radios in mid 2022. They are made in Japan.
If you switch to a two pole plug for the 2.5 mm plug I think it would work, based on my experiment.
I’m not sure that it worth the cost for shipping to return it. I’ll probably just order a cord for my FT5DR and if one of my friends buys an FT65 I’ll gift this cable to them.
Thank you for your help through this. I truly appreciate your customer support!
73 de AI7KS

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@K0TX ,
I’ve been wondering how difficult it would be to get a similar cable made except using a 2 pole plug for the 2.5 mm plug. Based on how quickly you went from discussing pin outs to stocking a new cable in this thread: Cable for Anytone AT-D578UV III Pro & Plus - #8 by K0TX
it appears to be relatively easy.

Also, I’m sorry I never thought to offer this before, would you be interested in me sending you the FT-65 cable and temporarily my FT-65 so you can see what you think?