[Elecraft] Repost: KX3 ACC1 interface - logic signal levels - what is "official" Elecraft standard for this ?

Tue Sep 25 13:55:02 EDT 2012

I assume that TTL-level means it works with a +5V/0V swing on input to 
the radio?

73, doug

On 25-Sep-12 14:33, Wayne Burdick wrote:
> Brian,
>
> The ACC1 port on the K3 is fully compatible with the RS232 standard,
> although it uses 0 V rather than a negative voltage when transmitting
> a low unit. This is the same TTL-level interface we use in several
> other products including the XG3, W1, W2, and K144XV. We offer both
> RS232 and USB cables that work with this port, and as far as I know
> these cables work with all laptop and desktop computers.
>
> You can certainly roll your own. I'll send you the schematic of that
> portion of the circuitry.
>
> 73,
> Wayne
> N6KR
>
>
> On Sep 25, 2012, at 7:09 AM, Brian Lodahl OZ2BRN wrote:
>
>> Hi,
>>
>> I'm reposting this because I'm still struggling to get my customized
>> CAT
>> + CW interface for the Kx3 to work:
>>
>> I attempted yesterday to wire up a TTL Serial cable from FTDI,
>> containg
>> both CAT as well CW keying (using #RTS), and I can easily get the CW
>> to
>> work (keying using #RTS through a 4N25 and two 1N5711 diodes for dit
>> and
>> dah), but it seems that the CAT does not work with this interface.
>>
>> My question again: -What is the "official" Elecraft electrical
>> specifications for the ACC1 interface ??? What voltage levels for Rx
>> and
>> Tx, respectively, with respect to GND or Positive voltage ?
>>
>> -Does anyone have a schematic of the ACC1 interface for Kx3 that I can
>> take a look at ?
>>
>> 73'
>> Brian OZ2BRN
>>
>>
>>
>>
>> Den 21-Sep-12 08:34, Brian Lodahl OZ2BRN skrev:
>>> Hi Kx3 users,
>>>
>>> Other posts have previously dealt with the issue that the standard
>>> KXUSB
>>> cable for Kx3 does not support CW keying from the computer to the Kx3
>>> radio, simply from the fact that as opposed to the ordinary serial
>>> connection (old RS-232 standard), the RTS and CTS pins are not
>>> available
>>> in the 3.5 mm, three-pin TRS jack connector for ACC1 in the Kx3.
>>>
>>> Pursuing this further, and not wanting to have more than one USB
>>> cable
>>> to my PC from my Kx3 for all of my buisness on the PC side, I want
>>> now
>>> to build a new interface cable using a custom cable assembly from
>>> FTDI:
>>>
>>> http://www.ftdichip.com/Products/Cables/USBTTLSerial.htm
>>>
>>> Then using either RTS or CTS flags in my PC's radio interface setup
>>> (log
>>> program Win-Test) to pull the CW key connection in the Kx3,
>>> possibly via
>>> a FET or Opto Coupler.
>>>
>>> - I have a 4N25 in mind for this ... with parallel coupling of two
>>> 1N5711 to the paddle dit's and dah's.
>>> I did the very same thing on my K2, and it worked like a charm.
>>>
>>> Checking the signal levels on my oscilloscope today on the ACC1 data
>>> connection, I find:
>>>
>>> Tip connection = Rx data from the computer to the Kx3 = 5,0 - 5,2
>>> volts
>>> level (generated by the FTDI line driver)
>>> Ring connection = Tx data to the computer from the Kx3 = 7,0-7,5
>>> volts
>>> level (generated by the Kx3 line driver)
>>> both with respect to GND being the sleeve pin of the ACC1 jack
>>> plug, and
>>> looking pretty, noise-free and free of any transients. Good, nice
>>> square
>>> signals with good integrity.
>>>
>>> Baud rate of the data here is obviously configurable, and with your
>>> PC's
>>> logging program so is the polling rate of how often the PC requests
>>> data
>>> from the Kx3.
>>>
>>> My question :What is the "official" Elecraft electrical
>>> specifications
>>> for the ACC1 interface ???
>>> What voltage levels for Rx and Tx, respectively, and what impedance
>>> to I
>>> terminate with when I interface with e.g. opto coupler for my
>>> project ?
>>>
>>> Would I be OK assuming I just use a 5-volt TTL-level cable version
>>> here,
>>> both ways Rx+Tx OK ?
>>>
>>> TTL-232R-5V:
>>> http://www.ftdichip.com/Support/Documents/DataSheets/Cables/DS_TTL-232R_CABLES.pdf
>>>
>>>
>>> 73'
>>> Brian OZ2BRN
>>> Kx3 # 1118, K2 # 6936 (to which I did the same mod)
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>>
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