[ICOM] Digital interface- no audio modulation problem on Icom 746 Pro

[Ken Winterling]

James,

Do you have the manual for the IC-746?  If so, go to page 72 (at least
it it 72 in my PDF).  There are charts for the ACC1 and ACC2
connectors.  ACC1 is the only connector that has the modulator input.
My HB PSK-31 interface is connected to ACC1 and works perfectly on HF
(I do not use it on VHF).  I can send you a road map if you are
interested.

Since you are using VHF as well as HF you will also need a connection
to ACC2, pin 6, for the VSEND transmit line.

Let me know if I can be of further assistance.  Good luck!

Ken, WA2LBI

On 5/22/06, James W. Long <JamesLong at wowway.com> wrote:
> Dear All
>
> Help! is my rig blown?
>
> I am having trouble with my digital interface.
>  it is home made and extremely simple.
>
>  this interface never "used" to work on this rig. this is the first time.
>  FOR THIS RIG.
>  this interface works PERFECT on a ICOM 706MKIIG and a Kenwood TM-V7.
>
>  I bought this rig new, and parts of it are still unknown to me.
>  have wired up a home make CIV interface and and
>  amplifier interface and have it wired for audio thru a DSP
>  and have it hooked up to 6M, 2M, 440 and HF Antennas.
>  So I'm not lost or anything here. I just need some direction now.
>
>  the problem:
>  the PSK sound out from the computer is not modulating,
>   all I see is rf, no carrier. with a second receiver
>  used to back monitor my transmitted PSK I do not hear it
>  except  way way way way way WAY WAY WAY
>  down in the dirt so low it is almost indistinguishable.
>  like crossover or induction or something. it is not strong. you
>  would not hear it unless you were looking for it with all the
>  volumes full up all the way in a quiet room.)
>
>  I have verified FULL audio is present all the way up the cable
>  and the computer volume is ALL the way UP.
>
>  how its wired:
>   PTT works perfect on HF and vhf.
>   its a small transistor / diode / resistor circuit,
>   which comes off serial COM1.
>   it brings PIN 3 on DATA socket, PIN 3 on ACC2
>   and PIN 6 on ACC2 to ground simultaneously as all these
>   pins are wired in parallel. no matter what amateur band
>   I go to, the Icom goes to xmit when I say so on the computer.
>   so that's working perfect.
>
>   audio (receive).
>   I can receive audio fine. I see PSK signals in mixw2 in the waterfall.
>   I can copy them fine.  the receive audio shares common ground
>   between radio and pc sound input.  I don't want a discussion of
>   this topic since its not the problem.   audio comes from
>   DATA socket PIN 4 and PIN 5 which are wired together and then
>   connected to the soundcard input with proper respect for polarity.
>
>   Audio send (The Problem)
>
>    Audio send shares common ground with the pc.
>   no discussion wanted on that subject.
>    the soundcard output has been traced all the way up the cable
>    with headphones and I verify full signal is present at the radio receptacle
>    where it plugs into DATA Socket and connects to PIN 1.
>
>    for the Icom 746 pro I have only added the ACC2 Plug with pins 3 and 6 wired
>    in parallel to the five pin DATA Plug pin 3.
>
>
>    I can successfully use this SAME cable into a Kenwood blue face TM-V7 which
>    has the IDENTICAL 5 pin DATA receptacle in the front on the left side
>    and it works perfect. I use an adaptor into my 706MKIIG and it also works
>    perfect.
>
>
>
>
>  what is my problem? what did I miss? is the input circuit on the 746 pro blown?
>
>  or is there some menu setting I need to make?  I try this on 14.070 USB
>  with NB off no compressor just generic settings. voice works fine.
>  I have made many voice contacts with this rig.
>
>  I just cant get audio to go from the back of the rig into the inside of the
>  rig. I still don't know everything about this radio so what am I missing?
>  it will transmit PSK over the microphone when I wire sound out thru my speakers,
>   but that is not the desired solution.  neither is interfacing to the mike input.
>
>
>  do you think the input circuit (PIN 1 on DATA) is toast?
>
>
>  Thank you in advance,
>   KC8RYX James
>
>
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