KIO2/KPA100 Serial Comm Problems

[Tom Hammond-3]

Hi Folks:

For quite a while I've blamed my KIO2 _and_ my KPA100 (s/n 0008) for some
serial communications problems I've been experiencing... I can SEND data to
the PC with no problem, BUT I cannot RECEIVE data FROM the PC...

Today, while getting a local's K2/100 (s/n 4224) ready for Field Dat (and
PC logging) I think I've determined that the problem may not be my K2, but
the PC!

The PC I've been using as an IBM ThinkPad 380D Laptop which USED TO
communicate very reliably with the K2... however, since about a year ago,
communications have been 'flakey' at best... sometimes on, sometimes off...
with no rhyme or reason (that I've been able to determine) to the failures.

I've now tried this laptop with two K2/100's and two different serial
cables of my manufacture and verified to be properly wired (in case someone
wants to ask). Serial comms work fine if the K2 is sending data, but fails
if the PC is sending it back to the K2.

I'm beginning to thing that maybe (and I've not yet scoped it to confirm)
that the signalling voltage on the RXD (K2 side) line may be marginal and
that the serial adapters in the KPA100s just can't quite decode the voltage
changes. Guess I'll hang a scope on it later today and see what's going on
there.

Last time I did this, I HAD data going into the MAX1406 (pin 6, R3IN/RXD),
but nothing coming out on R3OUT/K2 RX, which tends to imply that the
MAX1406 wasn't (or couldn't) decode the incoming data for one reason or the
other. I swapped out the MAX1406 and there was no change, BUT then,
sometime a bit later, all of a sudden serial comms picked back up and all
was well... and no, I'd not changed anything. At that point I blamed myself
for a poorly soldered connection somewhere in the serial comms section, BUT
since the problem also shows on a completely different K2, I now absolve
myself of that onus.

Has anyone else experienced a serial comms problem with their Laptop PC? I
know some Laptops tend to use RS232 voltages quite a bit less than those
used on desktop PCs, voltages which might cause problems under certain
circumstances.

Suggestions are ALWAYS most welcome.

73,

Tom Hammond   N0SS


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[Steven Pituch]

Hi Tom and All,
I had a similar problem with a non Elecraft I/O device.  I built an I/O
converter for a TS-850, before I realized how much better the K2 is and
sold the TS-850 ;o).  It's the standard Kenwood interface using a Maxim
chip and two opto-isolators.

I added LEDS so I could see activity.  I was not getting any activity
from the radio to the PC.  I noted that the opto-isolator, when tripped
by the Maxim voltage going high was taking far too much current.  It was
pulling the voltage of the Maxim down.  I solved this by putting a
standard 2n2222 amp between the optoisolator and the Maxim chip.  I made
sure the 2n2222 did not take so much current from the Maxim to disable
the output.  This did the trick.

Could it be that your receive rs232 port is drawing to much current from
the Maxim chip, and pulling the output of the chip down?  In this case a
2n2222a could boost the voltage to the rs232 port and reduce the current
used by the Maxim chip.

It should be easy to check the output of the Maxim chip with a DMM. If
it is being pulled down, try adding the amp.

Regards,
Steve, W2MY

PS I just got my KIO2 working on K2 #402.
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[Don Nesbitt]

Hi Tom - just a quick note to let you know that I use an old IBM 380ED (not
sure what the difference is between it and the 380D) with the K2 and
thankfully have not experienced the "flaky" communication problem that you
are having.  I also use it with the Yaesu Mark V and again no problems.

Just FYI - I'm using  XMLog as well as N1MM Logger and both communicate well
in both directions using the 380ED as well as with a 2.4 gig P4 laptop that
gets moved around.

A shot in the dark, but on occasion, I have noted problems reported by
others on other reflectors related to some specific piece of software and
the "polling" speed and the timing issues involved when used with various
radios.  Also note are problems with the settings of serial port in terms of
speed, parity, etc. Maybe this is an issue with the software and not your
faithful 380!  73 -- Don N4HH

----- Original Message -----
From: "Tom Hammond" <[hidden email]>
To: <[hidden email]>
Sent: Monday, June 13, 2005 9:10 AM
Subject: [Elecraft] KIO2/KPA100 Serial Comm Problems


> Hi Folks:
>
> For quite a while I've blamed my KIO2 _and_ my KPA100 (s/n 0008) for some
> serial communications problems I've been experiencing... I can SEND data
to
> the PC with no problem, BUT I cannot RECEIVE data FROM the PC...
>
> Today, while getting a local's K2/100 (s/n 4224) ready for Field Dat (and
> PC logging) I think I've determined that the problem may not be my K2, but
> the PC!
>
> The PC I've been using as an IBM ThinkPad 380D Laptop which USED TO
> communicate very reliably with the K2... however, since about a year ago,
> communications have been 'flakey' at best... sometimes on, sometimes
off...
> with no rhyme or reason (that I've been able to determine) to the
failures.
>
> I've now tried this laptop with two K2/100's and two different serial
> cables of my manufacture and verified to be properly wired (in case
someone
> wants to ask). Serial comms work fine if the K2 is sending data, but fails
> if the PC is sending it back to the K2.
>
> I'm beginning to thing that maybe (and I've not yet scoped it to confirm)
> that the signalling voltage on the RXD (K2 side) line may be marginal and
> that the serial adapters in the KPA100s just can't quite decode the
voltage
> changes. Guess I'll hang a scope on it later today and see what's going on
> there.
>
> Last time I did this, I HAD data going into the MAX1406 (pin 6, R3IN/RXD),
> but nothing coming out on R3OUT/K2 RX, which tends to imply that the
> MAX1406 wasn't (or couldn't) decode the incoming data for one reason or
the
> other. I swapped out the MAX1406 and there was no change, BUT then,
> sometime a bit later, all of a sudden serial comms picked back up and all
> was well... and no, I'd not changed anything. At that point I blamed
myself
> for a poorly soldered connection somewhere in the serial comms section,
BUT

> since the problem also shows on a completely different K2, I now absolve
> myself of that onus.
>
> Has anyone else experienced a serial comms problem with their Laptop PC? I
> know some Laptops tend to use RS232 voltages quite a bit less than those
> used on desktop PCs, voltages which might cause problems under certain
> circumstances.
>
> Suggestions are ALWAYS most welcome.
>
> 73,
>
> Tom Hammond   N0SS
>
>
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[Tom Hammond-3]

RATS!!!

Well, I think I've found the culprit of my K2 serial comms problem... and
it's the laptop!!!  Unfortunately!

My IBM ThinkPad 380D shown the following voltages:

Voltages:

   TXD line (from K2PA100):
      Quiescent:  -15VDC
   Sending data:  +5VDC


   RXD line (from IBM ThinkPad 380D):
      Quiescent:  -5VDC
   Sending Data:  +1.0VDC

Given data provided by Jack Brindle, W6FB, the TXD line appears to be about
1.4VDC under the minimum required voltage.

And no, the K2 is not pulling down (loading) the output from the laptop...
it reads the same connected to the K2 or not.

Not sure this is going to be something I can fix as if it were my K2!

Will advise if/when I DO get it fixed though.

73, and thanks to all those who have offered suggestions and support.

Tom   N0SS

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