[Elecraft] Can I split or share my ACC port?

[Don Wilhelm]

Hugh,

Certainly the ACC port can be split out to multiple destinations. But be 
careful if any one signal line is driving (or receiving) multiple 
boxes.  The original K3 design used open drain drivers on the signal 
lines so that the pullup resistors could be located in the most remote 
box while any other boxes on that same line would not have a pullup 
resistor.

(soapbox on)
But then many hams did not know what pullup resistors were, nor how to 
use open drain output drivers - and most other ham gear did not have 
provisions for adding pullup resistors at the end of the signal line - 
as a result the pullup resistors were moved into the K3 by 
modifications.  One of the complications that created was in the KPA500 
design where the KPA500 had to provide protection diodes on the band 
data lines because some band decoders put higher voltages on those lines 
- the K3 can handle that, but the KPA500 input circuits could not.
(soapbox off)

So, yes, you can split out the ACC connector to multiple places. Only 
one caution - if a single signal goes to multiple places, look at the 
situation carefully.  In general, there should be only one driver on any 
one signal line.  Multiple receivers are usually OK, but multiple 
drivers are a recipe for trouble.
Do NOT use a VGA splitter - find a splitter that implements all 15 
pins.  Many VGA splitters connect several lines to a common pin or pins. 
An alternative is to split out the 15 pin connector to individual signal 
connection points (a "fan-out box").


The RS-232 connection is different - that is a point to point signalling 
standard.  It can not be used with multiple drivers. Yes, there is a "Y" 
cable that can be used with the SteppIR controller, but that is because 
SteppIR put in a special mode where it only "listens" on the RS-232 
traffic, it does not transmit - therefore in that mode, the SteppIR end 
disconnects any RS-232 drivers.

73,
Don W3FPR

On 8/7/2012 4:43 PM, Hugh Bradley wrote:
> I spend a lot of my time connecting and disconnecting accessories from the
> back of my K3 and I find this tedious.
>
> In my shack I have a, Expert 1K linear amp and a Microkeyer II which both
> like to use the ACC Port on the K3 I use a Remote-rig unit to control the
> K3 when I am away and this too needs the ACC.
>
> Instead of connecting one of these items at a time, is it OK to use a VGA
> cable splitter and have both or three connected simultaneously?
>