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USB interface not triggering. No PTT function question

Discussion in 'Working Different Modes' started by 2E0ILY, Apr 19, 2012.

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  1. 2E0ILY

    2E0ILY Guest

    I am totally new to data comms and have loaded the current JT65 HF
    software and am using a USB driven interface cable from my Windows XP
    desktop PC to my old boat anchor Yaesu FT-902DM transceiver. the cable
    is from a UK company called radio Arena and is shown here (site can be

    It has a LED on the case to show (I assume) when it triggers the PTT.

    Using the JT65 "Test PTT" button the LED on the interface lights and
    the PTT RCA plug that goes to the PTT connector on the back panel of
    the transceiver goes closed circuit, tested with a continuity meter.
    The rig however does not go into TX mode. Shorting the PTT connector
    terminals on the transceiver sends it into TX mode. Am I missing
    something like it also needs an audio signal input, or
    misunderstanding the "Test PTT" function in JT65? Or is it likely a
    hardware issue with the interface cable? Thanks!
  2. ZR6MS

    ZR6MS Ham Member QRZ Page

    Check to see that the RTS function is activated.If not sure just send audio into the input ,some cables don't work when using the ptt test function.
    Hope it works.
  3. 2E0ILY

    2E0ILY Guest

    Not sure how or where to check if the RTS function is enabled. here's a schematic of the device, maybe this will help? Thanks.

    Attached Files:

  4. W9GB

    W9GB Ham Member QRZ Page


    Get those instructions from Radio Arena or your Yaesu FT-902 Owner's manual -- Looking at page 9, it tells you that PTT is grounded for remote PTT operation (e.g. foot switch).
    That is not how that interface works -- according to schematic you provided.

    Using your DVM, do you have 12 VDC on that Yaesu PTT center pin???
    The transistor in this Radio Arena USB interface is switched with 3.3 VDC going to ground ....
    Your FT-902 PTT, as described, operates when that center pin (Yaesu PTT) is Grounded ....
    That is NOT how this USB interface appears to work.

    Looks like you need an additional Relay or Switching transistor, for proper operation.

    You will have to ask Radio Arena about this Prolific USB chipset (counterfeit or real).

    Prolific has announced End of Life for this maligned USB chipset.
    End-of-Life (EOL) Notice:
    PL-2303HX(Chip Rev A) will be phased out at the end of October 2012. It would be replaced by PL2303TA which is pin-to-pin compatible with PL-2303HXA and PL-2303XA. Please refer to the PL2303TA PCN, Datasheet, and Migration Guide or contact Sales for more information.
    Last edited: Apr 19, 2012
  5. 2E0ILY

    2E0ILY Guest

    Wow, great reply, thanks for all the trouble you have so obviously taken! :) OK, just probed the PTT RCA socket on the back of the 902 and the centre pin shows + 12 volts relative to ground, yes. I'll see if I can work out how to use a small relay. I should have paid more for an interface. Was told by someone local it worked fine on his 902DM though, which seems odd. I hope I haven't knackered the switching transistor in the adaptor, although it's hardly my fault if i have, i just followed the instructions... Am I right in thinking then, I need a small NO relay that switches closed with about 3v applied to its coil? PITA, why don't things just "work"?

    Sincere thanks for your time and trouble, much appreciated. In a way i am glad it wasn't just me being stupid, but also find it od they sell these for a range of Yaesu boat anchors that all appear to trigger PTT similarly, yet according to the diagram can't possibly witch them.
  6. 2E0ILY

    2E0ILY Guest

    Here's the reply i have just received from Radio Arena:


    Sorry, we don't have spare staff to explain how to use software and datamode
    cables. Our front page clearly says - it will be assumed that the purchaser
    is knowledgeable in using the products for the applications they are
    designed for.
    The only thing I can say is that your radio is quite old model and SOME of
    these radios require more voltage to trigger full PTT. In this case you may
    send the cable back for refund, since we can't do more than 5V. And if 5V is
    not enough for your radio's PTT there is nothing you/we can do.

    In all other cases please learn manuals, software help, driver installation
    instructions etc etc



    Radioarena Hardware

  7. KO6WB

    KO6WB Premium Subscriber QRZ Page

    What you could do is make a trigger circuit for your FT-902. What you need is a 2N4401 or 2N2222 small signal transistor. Any small signal NPN transistor will work. Use a small plastic case and on one side put an RCA phono plug and on the other side an RCA phono jack. Use a 1K ohm resistor from the center pin of the RCA phono jack to the base of the transistor. Connect the collector of the transistor to the center of the RCA phono plug. Connect the emitter of the transistor to the shield connection of the RCA phono jack. Use a small piece of wire and connect the shield of the RCA phono jack to the shield of the RCA phono connector. Connect the PTT line to the RCA phono jack and plug the RCA phono plug into your rear panel PTT on the FT-902. Done, now you should be able to key the FT-902.
    The transistor if bought new cost a few pence, a resistor a little bit less.
    Try this and let us know how you've done.
    Last edited: Apr 19, 2012
  8. 2E0ILY

    2E0ILY Guest

    Not having a suitable transistor, and with sincere thanks for the idea, I found a PCB mount miniature relay with a 3 volt coil at 45 mA. I powered this from two AA cells, and it triggered fine form the output switching of my "faulty" gizmo. So I am putting it into a box and having it in line with the gizmo. Not ideal, but a cheap way to get it working to see if I actually enjoy data modes. I can only assume, looking at the specs for the optocouler, the current draw of the relay in the 902DM transceiver is too high to be switched. If I enjoy it I will probably upgrade to something like a SignalLink device. Thanks for all the help! I am about to post a separate thread re simple data software that is easy to set up for boat anchor rigs.
  9. KA9JLM

    KA9JLM Platinum Subscriber QRZ Page

    Why do you need batteries ?

    The drawing you showed , has the voltage supplied by the USB port.

    You should be able to just connect directly to the relay coil, and not have to worry about replacing batteries.
  10. 2E0ILY

    2E0ILY Guest

    The device just seems to change from open to closed circuit state, it gives no voltage output at all, that I can measure, that['s probably why i found the transistor idea rather odd, I thought I may have misunderstood, then found a relay.
  11. KA9JLM

    KA9JLM Platinum Subscriber QRZ Page

    Maybe the PNP transistor in the box is bad then.

    If it is good it should power the relay coil.

    Or the 3.3 volt regulator could be bad.
    Last edited: Apr 23, 2012
  12. 2E0ILY

    2E0ILY Guest

    I think there may be some confusion here, the encapsualted USB "thing" feeds down a moulded lead to what Radio Arena call the "main unit". The switching for the PTT function is done by an optocoupler.

    Attached Files:

  13. KA9JLM

    KA9JLM Platinum Subscriber QRZ Page

    That is confusing.

    Seems like it would have worked as is then.

    Sorry for the confusion. I was going by your original posted diagram.

    Operating a relay coil off of batteries will get old real quick.
  14. 2E0ILY

    2E0ILY Guest

    Seeing as i have the thing now at least it should get me up and running for no further outlay. Wish I'd never seen them and just got a SignaLink, but hindsight is a wonderful thing. Thanks very much for all your help!!
  15. W9GB

    W9GB Ham Member QRZ Page

    Based on new drawing, the opto-coupler, 4N25 is likely dead -- or you hooked up backwards.

  16. M1BCM

    M1BCM Ham Member QRZ Page

    It Works

    I have exactly the same radio and interface and it works just fine. In the JT65 settings, try both comm port 5 and "nothing" options. One of these will work with yours and it's the reason (almost 100% probable) your PTT is'nt activating.


  17. 2E0ILY

    2E0ILY Guest

    Nope, sorry Jeff, tried that, no joy at all. Moving the USB device from PC socket to PC socket gives the device a different comm port number as I would expect, but in no port does it do more tghan flash the LED on when the tset button is pressed. A meter shows the connector plug to the PTT on the rig change to closed circuit *IF* it's not connected to the rig. When it IS connected to the rig it doesn't cause the rig's relay to close. Altering the opptions boxes in JT65 makes no difference either. It WILL close a miniature 3 volt PCB relay, powered from two 1.5 volt cells. For now that is how I will have to operate it. I suppose I could post it to you to try on your own rig, or even drop it in as you aren't far from me at all. Did you sort a transformer out for it? Cheers Jeff.
  18. KA9JLM

    KA9JLM Platinum Subscriber QRZ Page

    A optic isolator should read like a Transistor junction. How are you measuring it as a closed connection ?

    Sounds like the 4N25 may be bad as W9GB pointed out. Or the polarity is reversed.
    Last edited: Apr 24, 2012
  19. 2E0ILY

    2E0ILY Guest

    I am just putting a DVM set to read continuity across the PTT plug, without the plug connected to the rig. It shows opened and closed circuit in tune with pressing the Test PTT button in JT65. But when connected to the rig it does not trigger the rig's internal relay. Shorting the rigs socket does trigger the internal relay and it goes correctly to TX. I have a semiconductor tester (this one: ) not sure if I can test an opto coupler with it, or if it will indeed test whilst still on the PCB? I don't really fancy trying to lift it and risk making things even worse as I have no replacement. If I reverse the PTT lead on the board of the USB device the rig goes straight to TX when I plug the lead in, even without using the PTT test button in the JT65 software.
  20. M1BCM

    M1BCM Ham Member QRZ Page

    1: Does it work for PSK?
    2: Sure you got the leads plugged into the right sockets ?
    3: Do you have the XP audio properties setup correctly (if it works in PSK then you do)
    4: Have you installed the drivers ? (not sure if you already answered that)
    5: Do you have the manual for the databox, if not i can email the PDF to you.

    My 902DM is'nt here Chris, still waiting for a transformer i'm afraid, if i get it back before you sort your problem out, you're very welcome to bring it over. :)


    PS: Check your vox level .. VERY important !

    Last edited: Apr 24, 2012
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