[Elecraft] K3S PTT using DTR/DTS issue

[Don Wilhelm]

Jerry,

Did you have the USB connection to the K3S still connected while you 
also connected the USB to Serial adapter into the RJ-45 dongle?

If so, that is a "No-no".  RS-232 (whether from the internal K3 USB to 
serial adapter or from an external adapter) is a one to one, point to 
point protocol.  It must have *only* one driver on the signal lines.
If you connected both at once, you had two drivers on the signal lines, 
and those two drivers would "fight with one another", possibly causing 
damage.
When one driver is trying to send a mark, the other trying to send a 
space, those two signals are of opposite polarity and can cause damage 
to one another.

So whether you damaged your external USB to serial adapter or if you 
damaged the internal USB to serial adapter in the K3S is indeterminate - 
damage could have been done to both.

73,
Don W3FPR

On 9/22/2015 10:42 PM, ae4pb at carolinaheli.com wrote:
> So my new K3S is running well and I'm setting up my software and see that it
> can do digital modes and control PTT using a comm port. I open my owners
> manual, page 20, which says I can use that connection for control and PTT.
> I'm already using the USB for control so will just use it for PTT. I have a
> USB to serial adapter so I install it, plug in the RJ47 connector to the
> rig, mate the DB 9 connectors and immediately smell burning components,
> Quickly disconnect the DB9.
>
>   
>
> I was previously using this serial adapter successfully on a YAESU FT-897D
> before I sold the rig to get the K3S.
>
>   
>
> So now the questions:
>
> 1.   Why did this apparently experience an issue? I see nothing in the
> manual to indicate this requires anything but a standard connection.
>
> 2.   How much damage has been done to my brand new k3S using the supplied
> Elecraft cable and a known good previously good USB to Serial cable (MFJ I
> believe).
>
>   
>
> I'm heartsick. Being the type of person who checks and double checks things
> I can find nothing wrong with what I did and yet apparently I've damaged
> something.
>
>   
>
> Tomorrow I'll pull the cover and check the board.
>
>   
>
>   
>
> Jerry Moore
>
> AE4PB, K3S - S.N. 010324
>
> An Amatuer is - Considerate, Loyal, Progressive, Friendly, Balanced, and
> Patriotic.
>
>   
>
>   
>
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