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

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OZ2BRN Brian Lodahl

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

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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OZ2BRN Brian Lodahl

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

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)
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>

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Don Wilhelm-4

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

Brian,

The schematics for the KX3 is not yet available. However, I believe the
KX3 CAT interface is the same as that used in the XG3 signal generator
(if not exactly the same, it is similar). You can download the XG3
manual and find the schematic at the back.
The CAT interface should tolerate the full RS-232 voltage swing, but
should respond to positive going levels greater than 3 volts and the
output level will swing up to 9 volts (but does not go negative).

73,
Don W3FPR

On 9/25/2012 10:09 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)
>> ______________________________________________________________
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:[hidden email]
>>
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
>>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>

wayne burdick

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

Administrator

In reply to this post by OZ2BRN Brian Lodahl

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)
>> ______________________________________________________________
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:[hidden email]
>>
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
>>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html

Doug Faunt N6TQS +1-510-655-8604

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

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)
>>> ______________________________________________________________
>>> Elecraft mailing list
>>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>>> Help: http://mailman.qth.net/mmfaq.htm
>>> Post: mailto:[hidden email]
>>>
>>> This list hosted by: http://www.qsl.net
>>> Please help support this email list: http://www.qsl.net/donate.html
>>>
>>
>> ______________________________________________________________
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:[hidden email]
>>
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>
>

Don Wilhelm-4

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

Doug,

Yes, by definition a TTL-level input should respond to a high input of 2
volts or greater while a low level is 0.8 volts or less.
Just as additional information, if an input is CMOS compatible, it will
respond to a high level of 3.5 volts or more and a low level below 1.5
volts.

73,
Don W3FPR

On 9/25/2012 1:55 PM, 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?
>
>

______________________________________________________________
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Post: mailto:[hidden email]

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wayne burdick

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

Administrator

In reply to this post by Doug Faunt N6TQS +1-510-655-8604

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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