[ICOM] Opto-Isolators (Was Computer Control Interface)

Thu Dec 29 00:17:06 EST 2005

Most common opto isolators have just transistor outputs or darlington transistor outputs.  These transistors can be driven into saturation with reasonable current through the LED part.  Given a reasonable opto with the gain you need (some optos actually have gain equal to or less than 1), I don't see why you would need a third transistor (the darlington pair of the opto driving an external transistor).  I have used optos to directly key many different makes and models of radios.

At 12/28/2005 06:08 PM, W7RY wrote:
>Thanks Larry.
>
>I wanted to keep the computer and rig isolated thus the opto isolators
>and transformers for the sound card. 
> 
>I may attempt to drive a keying transistor with the opto-isolator.
>
>73
>Jim W7RY
>
>
>-----Original Message-----
>From: icom-bounces at mailman.qth.net [mailto:icom-bounces at mailman.qth.net]
>On Behalf Of Larry Winslow
>Sent: Wednesday, December 28, 2005 2:45 PM
>To: ICOM Reflector
>Subject: Re: [ICOM] Opto-Isolators (Was Computer Control Interface)
>
>Jim,
>
>You'll definitely have to drive the 765 key input 
>with a transistor. I struggled laboriously for 
>several days trying to get an opto-isolator to 
>work with my 765. I finally removed the 
>opto-isolator and drove a 2n2222 transistor thru 
>a 4.7k resistor - that has worked ever since.
>
>73 - Larry WØNFU
>larry_w at comcast.net
>
>At 02:30 PM 12/28/2005, you wrote:
>>Speaking of opto-isolators...
>>
>>I'm having a difficulty keying the key (on the straight key input) of
>my
>>Icom 765.  The opto-isolator worked just fine with the 1000MP but not
>>with the 765. I may have to install another transistor after the
>>opto-isolator.
>>
>>Just food for thought.
>>
>>73
>>
>>Jim W7RY
>>
>>
>>-----Original Message-----
>>From: icom-bounces at mailman.qth.net
>[mailto:icom-bounces at mailman.qth.net]
>>On Behalf Of Gary Fiber
>>Sent: Wednesday, December 28, 2005 8:12 AM
>>To: ICOM Reflector
>>Subject: RE: [ICOM] Computer Control Interface
>>
>>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
>>
>>
>>----
>>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/
>
>----
>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/