K2 key autodetect problems

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K2 key autodetect problems

ae5ka
I have the external circuit using two diodes to allow the K2 to detect when
a straight key is used instead of the paddles. Occasionally with the paddle
plugged in but not keyed, the K2 will  spontaneously start sending a string
of dashes. This will terminate, sometimes only briefly, when I do key the
paddle. It happens even when K2 transmit power is turned all the way down,
and I've never had trouble with RF in the shack.

Both diodes test fine, at 0.64V drop forward, and no detectable leakage
reverse. The paddle also tests fine, both lines open when it isn't being
keyed, and likewise the autodetect box shows no shorts to the ohmmeter.

Ideas?

73
Chip
AE5KA
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Re: K2 key autodetect problems

Victor Rosenthal 4X6GP
Does it happen when the paddle is NOT plugged in?
If not, suspect the paddle jack.

FWIW, I also used this method to allow the K2 to be keyed by the N1MM
program. I mounted the diodes on the control board of the K2 and brought
out the keying line via the ALC pin on the DE9 connector, since I never
use ALC. My K2-to-computer cable has the DTR line connected to the
(formerly) ALC pin, and I set N1MM to key it via DTR.

Anyway, I never had any trouble with this system. I think I used
Schottky diodes which had a somewhat lower forward voltage.

73,
Victor, 4X6GP
Rehovot, Israel
Formerly K2VCO
http://www.qsl.net/k2vco/
On 27 Mar 2018 21:36, Chip Stratton wrote:

> I have the external circuit using two diodes to allow the K2 to detect when
> a straight key is used instead of the paddles. Occasionally with the paddle
> plugged in but not keyed, the K2 will  spontaneously start sending a string
> of dashes. This will terminate, sometimes only briefly, when I do key the
> paddle. It happens even when K2 transmit power is turned all the way down,
> and I've never had trouble with RF in the shack.
>
> Both diodes test fine, at 0.64V drop forward, and no detectable leakage
> reverse. The paddle also tests fine, both lines open when it isn't being
> keyed, and likewise the autodetect box shows no shorts to the ohmmeter.
>
> Ideas?
>
> 73
> Chip
> AE5KA
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Re: K2 key autodetect problems

Don Wilhelm
In reply to this post by ae5ka
Chip,

A string of dashes means somehow the dash line is being activated (or
grounded) - normally the ring contact on the key plug unless you have
reversed the paddles.
Do you have the key plug inserted all the way?

Put a bare stereo plug in the key jack and read the voltage on the tip
and ring - you should see 5 volts.

Look at the R1 and R2 resistors on the RF Board next to the key jack,
they should both be 220 ohms (they may be easier seen by removing the
left side panel).

If that is all good, consider replacing the diodes with Schottkey diodes.

73,
Don W3FPR

On 3/27/2018 2:36 PM, Chip Stratton wrote:

> I have the external circuit using two diodes to allow the K2 to detect when
> a straight key is used instead of the paddles. Occasionally with the paddle
> plugged in but not keyed, the K2 will  spontaneously start sending a string
> of dashes. This will terminate, sometimes only briefly, when I do key the
> paddle. It happens even when K2 transmit power is turned all the way down,
> and I've never had trouble with RF in the shack.
>
> Both diodes test fine, at 0.64V drop forward, and no detectable leakage
> reverse. The paddle also tests fine, both lines open when it isn't being
> keyed, and likewise the autodetect box shows no shorts to the ohmmeter.
>
> Ideas?
>
> 73
> Chip
> AE5KA
> ______________________________________________________________
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> Please help support this email list: http://www.qsl.net/donate.html
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>
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Re: K2 key autodetect problems

Mike Harris-9
In reply to this post by ae5ka
Hi Chip,

Not saying this is your problem but my Bencher twin paddles started
going random nuts. The contact gap is small, less than the thickness of
a sheet of 70gm paper. During keying it would stick one side or the
other. It turned out to be the screws fastening the contact pillars not
being tight. I guess over the years the plastic insulating washers must
have compressed allowing the pillars to imperceptibly move.

Since tightening them, the only problem with the paddles is me.

Regards,

Mike VP8NO

On 27/03/2018 15:36, Chip Stratton wrote:
> I have the external circuit using two diodes to allow the K2 to detect when
> a straight key is used instead of the paddles. Occasionally with the paddle
> plugged in but not keyed, the K2 will  spontaneously start sending a string
> of dashes. This will terminate, sometimes only briefly, when I do key the
> paddle. It happens even when K2 transmit power is turned all the way down,
> and I've never had trouble with RF in the shack.
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Re: K2 key autodetect problems

ae5ka
Great ideas to investigate, guys. I'll have to look into it over the next
week. The problem never occurs with paddles unplugged, and I haven't seen
it happen when plugged directly into the key jack on the radio.

I'll report back when I figure it out, or if I don't!

73
Chip
AE5KA

On Tue, Mar 27, 2018 at 6:57 PM, Mike Harris <[hidden email]>
wrote:

> Hi Chip,
>
> Not saying this is your problem but my Bencher twin paddles started going
> random nuts. The contact gap is small, less than the thickness of a sheet
> of 70gm paper. During keying it would stick one side or the other. It
> turned out to be the screws fastening the contact pillars not being tight.
> I guess over the years the plastic insulating washers must have compressed
> allowing the pillars to imperceptibly move.
>
> Since tightening them, the only problem with the paddles is me.
>
> Regards,
>
> Mike VP8NO
>
> On 27/03/2018 15:36, Chip Stratton wrote:
>
>> I have the external circuit using two diodes to allow the K2 to detect
>> when
>> a straight key is used instead of the paddles. Occasionally with the
>> paddle
>> plugged in but not keyed, the K2 will  spontaneously start sending a
>> string
>> of dashes. This will terminate, sometimes only briefly, when I do key the
>> paddle. It happens even when K2 transmit power is turned all the way down,
>> and I've never had trouble with RF in the shack.
>>
> ______________________________________________________________
> 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
> Message delivered to [hidden email]
>
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