[ICOM] Computer Control Interface

[Gary Fiber]

Well when I was working at Icom the easiest way to provide a hard 
ground was to use a transistor externally, no mods required to the 
equipment controlling the rig. We could not suggest to the customer 
how to modify his after market equipment to make it work with Icom products.

I looked at a HM-14 schematic, when you place a hard ground the U/D 
connection rig tunes up in frequency, when you ground through a 470 
OHM resistor the rig tunes down. I was remembering the troubles I 
went through with a customer and his DSP-2232 and using the Opto 
isolator to drive a transistor was easiest at the time. Some programs 
would control the frequency up / down mode in the DSP-2232. Others 
would use an external antenna, radio frequency controller.

When I saw the schematic of the MFJ-1289 I assumed Bob might be 
experiencing the same issue since the manual reads use the CW out for 
FSK keying. I did not get into it to far though.
I am using a Rig Blaster No Mic and just picked up a Tigertronics 
Signalink SL-1+ for my IC-718.

Buxcomm has a huge site I was hoping to find the product Bob was 
using and have a look at the schematic to find any differences in the 
FSK Keying as that unit seems to work for him.

>If you are using an opto to do CW keying via the UP/DOWN function, 
>then you should be aware that the UP/DOWN sensing in the Icom is 
>done by voltage.  That is, it senses the voltage on the UP/DOWN 
>line.   The UP/DOWN line is also used for the 4 voice/CW memory 
>keying but in that case, it senses 4 voltages

What Icom rig uses the U/D line for Voice and CW memory keying? Must 
be the newer models as the older one didn't so far as I remember.

Gary K8IZ

>.  What this means is, if you are using a transistor to key that 
>line, whether it is the output of an opto or discrete transistor, 
>you have to account for the Vcesat of the transistor in presenting 
>the line with a voltage.  The UP/DOWN buttons have no voltage across 
>them when they are on.  The Vce sat could be several tenths of a 
>volt.  If you do the calculations, understanding the internal series 
>resistance that is in the radio and the unloaded voltage, you can 
>come up with 4 new values of resistance for the keyer and probably a 
>new value for the UP/DOWN.  I have done that for the keyer with 
>great success.  The only catch with the UP/DOWN, is that it only 
>uses one resistance, with the other state grounding the line.  This 
>may present a problem if the voltage detection is looking for 
>something less that the saturation voltage of the transistor.  I 
>have not done an UP/DOWN keyer, so I can't say whether it will work 
>or not, but I have done computer controlled interfaces using the 
>memory keyer with optos/transistors.
>
>
>At 12/27/2005 12:42 PM, you wrote:
> >Bob,
> >
> >I was looking at the MFJ-1279 schematic and the CW out is using a 
> Opto Isolator. In the past I remember an Opto isolator not being 
> able to place a hard enough ground on the Icom UP / Down input.
> >The AEA DSP-2232 users had to install a transistor to provide hard 
> enough ground so the DSP-2232 would cause a frequency change, 
> mostly to the IC-970. This was done for Doppler shift frequency tracking.
> >I looked at the Buxcomm site but he has some much stuff it would 
> take a week to find the product you are using listed.
> >
> >Gary K8IZ
> >
> >At 07:58 AM 12/27/2005, you wrote:
> >>Ok I give up on this little project, it is quickly
> >>becoming not worth my time.
> >>
> >>Is someone using an interface with an Icom PRO or II or
> >>III that does all the soundcard modes and FSK modes along
> >>with keying CW from A SINGLE COMM PORT that actually
> >>works?
> >>
> >>I would like to know what your using so I can look into
> >>getting one.
> >>
> >>What is recommended by you guys with the experience?
> >>
> >>
> >>
> >>  73 fer nw,
> >>Bob AD5VJ
> >
> >----
> >Your Moderator: Dick Flanagan K7VC, icom-owner at mailman.qth.net
> >Icom Users Net: Sundays, 1700Z, 14.316 MHz
> >Icom FAQ: http://www.qsl.net/icom/
>
>----
>Your Moderator: Dick Flanagan K7VC, icom-owner at mailman.qth.net
>Icom Users Net: Sundays, 1700Z, 14.316 MHz
>Icom FAQ: http://www.qsl.net/icom/

Gary Fiber K8IZ
GROL PG-19-6691
Washington State Resident