Icom CI-V interface with 222

Discussion in 'Homebrew and Kit Projects' started by W4INF, Aug 29, 2008.

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  1. W4INF

    W4INF Ham Member QRZ Page

    (Sorry, title was supposed to be Icom CI-V interface with 2222)

    My ebay special just died. The second in a year. The price was sweet, about $10 with shipping to the door! But it died. Just like the last one. Both lasted about 6 months.

    Well, this is a good time to build the one I found on the web!!


    A trip to RadioShack and someone must have been looking out for me, because they had all the parts I needed in stock! I actually got enough parts to build about 4 of these, total invested about $20.

    It took me about an hour to wire it up... And its not pretty, at all! BUT IT WORKS! So I pat myself on the back! Been a while since I tinkered with projects like this, and I wasnt about to give up!









    I have Ham Radio Deluxe set to 9600 baud (19200 did seam to work) with 200ms repole/refresh timing. 100ms seamed to be too fast for the circuit. But so far, it appears to be working 100% FB...

    Interface is now connected to the physical serial port of the laptop (Dell Inspiron 600M), it was running off a USB serial port interface. HRD is working 100% FB with 19200 baud and 100ms repoll/refresh rate!!

    This one is working on my Icom 718, now I need to build another (already dreading it! HA HA) for my 706 that I use for portable/field!

    BTW, CAT-5 network cable (see pic) makes some really nice stranded hookup wire!!!!!

    Last edited: Aug 29, 2008
  2. K9FV

    K9FV Ham Member QRZ Page

    Been using that same circuit for several yrs now, first on a 706, now on my 756Pro with HRD - works like a champ, and pretty easy to build.

    I've been looking at trying to clean up my construction some, perhaps build it inside a DB9 shell for a neat project? Your project is neater than my project.... I used an old plastic box scrouged from somewhere that already had a hole or 3 in it, but it was CHEAP!!

    that's what ham radio is all about - having fun, melting solder, smelling rosin...

    73 de Ken H.
  3. W4INF

    W4INF Ham Member QRZ Page

    You mean, getting frustrated, melting carpet with solder that feel off the iron and smelling your skin burn when you slip? :D

    Yup, the hobby is great is many ways! Ill be mounting mine inside a project box from the Shack, I think I have one on the shelf.

    Oddly, CI-V does not want to work very good using a USB to serial interface, but when plugged directly into the physical serial port, works most perfect! Then again, the interface I bought demonstrated the exact same behavior. I likely should have spent more than 6$ on ebay for my USB/DB9 contraption. I am using it fine for keying with DigiPan etc..

    Thx for looking and posting!
  4. KB1KIX

    KB1KIX Ham Member QRZ Page

    I built and gave away one a few years ago (don't remember if it was based on this or something I saw with a Max232).

    I like this, and..... I'm looking for a project to start using ExpressPCB software.

    I like the idea about going tiny and building it into the housing of the connector.


    Funny thing about my local RatShacks (I have 3 nearby). Many parts I need, they don't have enough of in stock (ever try get standoffs from them lately!). I go and scoop parts at all of the shacks and they are "slightly" stocking a few more of each item.

    They are starting to take advantage of those wanting to tinker a bit like the projects in Make: Magazine. Projects every month.

    This, could be a good thing.

  5. KB1KIX

    KB1KIX Ham Member QRZ Page

    Forgot to mention - Cat5 as hookup wire rocks!

    I use it on many of my projects.

    Don't know why, but it looks neat when you need to wires on several parts of a project and you use the solid, and the solid white wires.

    Cheap to, as I often find busted cables at work that would normally be thrown away. One 15 foot run lasts for quite a few QRP projects.


  6. K5UOS

    K5UOS Ham Member QRZ Page


    I don't know what you mean, "... And its not pretty, at all!"

    It works and you made it! That is 99.6% the beauty!

    And the construction is about as nice as one can get with prototype board.

    These are the practical projects that are going to inspire others to start building.

    I like coming here to HP & D everyday and seeing what everyone is building or fixing.

    Thanks. K5UOS
  7. KC0ZJZ

    KC0ZJZ Ham Member QRZ Page

    Hmm, on a standard PC serial port Pin 4 (DTR) puts out a nominal 12V. So with the diode drop, the base-emitter drop, the 4k7 pullup, and the 4k7 base resistor; the tip of the CI-V jack will be pulled up to about (12-1.4)(4k7/(4k7+4k7))+0.7 or about 6 volts. This is a touch high for the radio, wich I would assume has a pullup to it's 5 volt rail. A better choice for the pullup (the one on the left) would be 6k8 which would put the tip at 5volts. In the actual circuit the tip voltage may be less because of loading. Apply a volt meter to the tip while the circuit is connected to the PC and idle(software open,but not talking to radio), and not connected to the radio. If it is above 5v I'd adjust the circuit.

    On all of the USB serial ports I've looked at (ripped apart) they use a charge pump similar to the way the MAX232 chip works. Here the DTR signal is only 9 volts or less, and can't tolerate as much loading. So I'm not supprised that the circuit is less optimal connected to one of these. The trouble with optimizing this circuit for a USB serial addapter is that if you forget and connect it to a regualar PC serial port the possibility of overvoltage applied to the radio exists.
  8. W4INF

    W4INF Ham Member QRZ Page

    ZJZ, TU for the tips.. So, you suggest replacing ALL the 4K7 resisters with 6K8 value??

    Or the 4K7 that is connected to the left transistor only?

    Wanted to make sure I understood accurately. I can follow schematics fairly well, but understanding everything or designing from scratch is a bit beyond me at this stage.

  9. KC0ZJZ

    KC0ZJZ Ham Member QRZ Page

    Yes, I did mean only the one on the left transistor.

    But in your case, since you are connected to a laptop, I'd leave the circuit alone. I just measured some serial ports here. The one on my desktop puts out a healthy 12volt signal on the DTR and signal pins. But the one on the laptop, a Dell Latitude, only gets to about 5.8 volts. This just barely falls short of the spec. which states >6 volts for a valid signal. Figures, since laptops don't have any other use for +/- 12 volt power, they are also likely to be using the charge pump technique.

    A volt meter is your friend. Even a basic cheepie is ok to get started.

    If the voltage on the tip is under 5 volts, leave the circuit as is.
    The serial port needs to be "opened" (in use) for this test. If the serial port is not in use the DTR signal will be a negative voltage, and the voltage on the "tip" in this circuit will measure close to 0 volts.

  10. KB1KIX

    KB1KIX Ham Member QRZ Page


    Did you keep a list of the RatShack part numbers?

    My local store is a pain to find anything unless I have the numbers (remodeling or something scary).

    This way, what they don't have, I'll have delivered.

    Thanx either way,

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