[TenTec] Omni V.9 Erratic CW Mod

[Anthony Bowyer]

   I've had several requests for info on the Erratic
CW mod, so I thought I'd post it. 

   Here's my best effort at 'ASCII Cad' for the
erratic CW mod. Basically this thing just checks for
Transmit Enable to come on (connector 66, pin #1, I
believe I'm counting correctly, anyway it's the one on
the left looking from the front of the rig) and then
opens the serial connection from the MAX232 to the hex
buffer, so nothing gets to the microprocessor
(commands are still echoed to the PC however). The
capacitor adds a very slight delay so there's no
chance that polling could occur between dots.
  I took power from the leads already on the 7417. I
had already added a decoupling cap across them (.1mf)
just in case.
  The relay I used was a small 5 vdc Omron SPDT that
came out of a modem. Has about 350 ohm coil. I'm sure
this isn't too critical as long as it doesn't draw
huge amounts of current and switches pretty quickly.
  The delay is just noticeable (by ear) with the 1 mf
electrolytic capacitor. It would probably work with a
smaller value, but this is what I tested with and it
works well. 
  I made the connection to the back of connector 66 by
using a small tipped iron and quickly 'tinning' the
connection (note "Quickly"!!), tinned the wire to go
on it and "Quickly" tacked in on. The heat didn't seem
to bother the connector at all.

 
                                 Sub mini SPDT
                      1mf         5V DC Relay
                       -  +         coil
                      +-][---+------mmmmm--->  5v+
                      |      /  C
     1N4148    4.7k   |  B |/    2N2222       
  <---->|-----/\/\/\--+----|     (NPN)       
  to Pin #1                |\                 
  on Connector 66            v               
  (one on the left           | E            
   looking from             ---            
   front of                 ///       
   rig)                                       
                             
    Please refer to Carl Moreschi's documentation of
the V.9 upgrade. Pages 9-14 is a description of the
RS-232 modification. Basically the Normally Closed
contacts of the relay goes between the 7417, pins 4&5
(connected together in the V.9 mod), and the bridged
traces on the Logic board (also done with the V.9
mod).  Just imagine cutting the wire in the middle
from the 7417 pins 4&5 to the traces on the logic
board and putting the NC relay contacts in between. 


Normally Closed Relay Contacts

   +------ to 7417 pins 4 & 5
   |
   v
 --------  to bridged traces on Logic board  


   I tested this now for about an hour and it works
very well. I thought the delay might cause some
problem if you tried to tune very quickly after
transmitting, but I wasn't able to see any issues with
it.
   I tested this with N1MM Logger and CIV Commander,
but it should work with any software that works in a
similar way to get/send rig info. 

   One other note: N1MM Logger polls a bit too often
for the Omni and will occasionally display a strange
frequency. It usually recovers pretty quickly. I think
it's because the Omni processes the send and receive
messages pretty slowly and the software polls again
before it's finished with the previous request. I
found that polling set for anything less than about
300 ms causes the problem. Unfortunately, this logger
doesn't have a poll frequency option (yet anyway!).
This mod won't help this problem. More a software
issue. 
 
   Way too simple, isn't it! I sent this message to
myself and the diagram display's fine in Yahoo mail
and Outlook. Let me know if you have any problems
reading it.  

Anthony  

=====
NT4X

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