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

Tue Sep 25 17:01:25 EDT 2012

The input can accept the full RS232 range, +/- 25 V. But 0-5 V will  
also work. In fact 0-3 V will work.

Wayne
N6KR

On Sep 25, 2012, at 10:55 AM, Douglas Faunrt N6TQS +1-510-655-8604  
wrote:

> 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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