[Elecraft] K2 - KPA100 RS232 interface repair

[Mickey Baker]

RJ45 is commonly used for RS232C. Millions of Cisco routers and switches built over the past 20+ years use this arrangement, as do many other devices. I have a half dozen of these cables - they once were shipped with the router. Although I don't know for sure, I'll bet the pinout is the same as Cisco. 

I can make up 10 RJ45 connectors in the time it takes to make a soldered DB9. 

Historically, RS232 was used in electromagnetic applications where there was a need to drive a relay with line levels. Since modern equipment doesn't need this - since TTL became commonplace in the 1970's - and since many lower power devices no longer have 12V power supplies, it has been practice to observe a ONE state at a voltage of 3V+. 

If you really want some detail, check out the data sheet on your favorite RS232 driver chip. Here's an example:
http://cds.linear.com/docs/en/datasheet/11801afb.pdf

73,

Mickey N4MB

> On Aug 22, 2015, at 8:31 PM, Bob McGraw - K4TAX <rmcgraw at blomand.net> wrote:
> 
> The K3S has a RJ-45 connector for the RS-232 communications.  Now that's different!   Of course they supply a cable with a RJ-45 on one end and a DB-9F on the other.  And then to keep everybody happy, there is what appears to be a 15 pin VGA connector that is the ACC connector to provide band data and such.  The manual clearly states "This is not a VGA video connector".
> 
> Yes it is very important to read and understand the manual before plugging or inserting any connector into any hole on any radio today.  It seems most hams think if it plugs in, then it should work.
> 
> 73
> Bob, K4TAX
> K3S s/n 10,163
> 
>> On 8/22/2015 7:17 PM, Richard W. Solomon wrote:
>> It seems to me that using a DB-9 connector for non-RS232 uses is taking the
>> Easy way out.
>> There are numerous other connectors that could be used to alleviate any
>> Misunderstanding.
>> 
>> Not everyone goes through manuals with a fine tooth comb to locate the
>> "gotchas".
>> 
>> 73, Dick, W1KSZ
>> 
>> -----Original Message-----
>> From: Elecraft [mailto:elecraft-bounces at mailman.qth.net] On Behalf Of Jim
>> Brown
>> Sent: Saturday, August 22, 2015 4:25 PM
>> To: elecraft at mailman.qth.net
>> Subject: Re: [Elecraft] K2 - KPA100 RS232 interface repair
>> 
>> Hi Floyd,
>> 
>> I've owned and operated a pair of K2s, both of which I bought used.
>> Elecraft makes it very clear that the DB9 connector on the K2 is NOT an
>> RS232 interface, that it is not RS232 compliant, and that a standard
>> RS232 cable should NOT be used. Rather, the DB9 connector provides both
>> serial control AND several control functions.
>> 
>> The DB9 connector is a generic part, and can be used for many things besides
>> RS232.  It is also well known that while the RS232 Standard defines voltage
>> levels, MANY modern products produce far less than those levels.
>> 
>> I've owned a lot of gear in my lifetime, and the first thing I do is open
>> the manual, study it, study the wiring of the various connectors, study the
>> specs, and study the operating instructions.
>> 
>> 73, Jim K9YC
>> 
>> 
>> 
>>> On Sat,8/22/2015 1:28 PM, Floyd Sense wrote:
>>> Hi Don. I'm sure you're aware that the RS232 spec includes the
>>> description of voltage levels, and if you're going to refer to an
>>> interface as RS232 (as Elecraft does in many places) then you're
>>> implying that the normal RS232 signal levels will be used.  A user
>>> shouldn't be required to read a one hundred page manual before
>>> plugging in a connector when every other such connector works in the
>>> conventional way.  Having been a designer using RS232 interfaces 45
>>> years ago, I would have been executed had I designed something like this.
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> 
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