Re: 7000 TX always remains on.

Steve W3AHL


The AL-82 keying interface spec (sinks 100 ma. at 12VDC) is well within the 7K's spec of sinking 200 ma. at 16 VDC.  so unless something is wrong with the amp or station grounding, the 7K shouldn't have been damaged.

Jumpering SEND1 directly to 8 VDC is a BAD idea.  SEND1 becomes SNDL, which connects to the CPU's Port 4 on pin 116.  Port 4 inputs are only rated for an absolute maximum voltage of 3.9 VDC.  If you notice, on the DDS board, SEND1 is pulled up to 8 VDC through a diode (for isolation) and a 2.2K resistor.  Subsequent 3.3K series resistors on the Main board, along with a 3.3K to ground and another diode drop keep the voltage below 3.9 VDC.  I would disconnect the jumper to 8VDC, to avoid damaging the CPU.  

Look at D1102 and R1106 on the DDS board.  If they are blown, that would prevent SEND1 from being pulled high when inactive, causing TX to always be active.  Also check Q1102, which pulls SEND1 and SNDL low when PTT is active.  It sounds like it is probably OK, although pulling down 8VDC when PTT is active is probably stressing the transistor!  

Are you using the standard HM-151 mic?  Does the TX LED on the MIC work when it's plugged into the front panel?  The HM-151 doesn't use the SNDL/PTT line to key the TX -- that line only turns on the TX LED on the MIC.  PTT is a command sent over the serial data bus on the mic interface.  If you are using some other mic, then it uses SNDL for PTT, with the CPU driving SNDS, which controls Q1102 on the DDS board.

Let us know what you find or if you have questions still.  This shouldn't be too hard to troubleshoot with a DVM and a magnifying glass....   Finding the parts on the PCB is half the battle!

Steve, W3AHL

---In ic7000@..., <syl2610@...> wrote :

Hi   thank you for the answer   
 my call is va2kv  sylvain
and the amplifier was an  Ameritron AL-82 Linear Amplifier  i just sold it

connected the amp directly to the ACC connector of the icom 7000
and when i  tune the amp    .. the radio  stay in tx  and the tx  red light is always on
i  did a hard reset of the radio and  its always  in tx 

i made a little wire  jumper in the dds board ( just for a test   between   SEND1   and  8VA )  and the radio is return to normal  is working well  .. but i know its not  suppose to be like that with a jumper   its a part inside who is defect,  but where ???
and the rear mic  jack is not working too..  no ptt when i push the ptt button    its only transmit  with the front mic jack  ..  the original mic is working well   all the button is working i tried the radio on the air
 and all station   told me that is  very good   for now..
  i try to fix by myself i have the service manual  of the icom 7000

ok 73

Join to automatically receive all group messages.