K3- external keyer problems

[alsopb]

Guys,

Out of the blue, the external keyer input to the K3 produces mushy dits
at higher speeds.   It seems that each dit has a tail which reduces the
off time till the next.  This happens in the TEST mode as well as with
RF output.  It is most noticable above 25 wpm on S,H,5 characters.  The
first dit sounds OK but it gets worse with following dits.

I've tried two different keyers and now the parallel port keying is
exhibiting the same.  I don' think it is a keyer issue since hooking the
keyers up to an audio oscillator sounds just fine.

I'm using firmware V2.76.   I dropped back to 2.67, where I never had
observed this, and the problem is still there.

The internal keyer does not have this problem.  If anything the dits
seem to get shorter as one goes above 30 wpm.  That I'm sure is just a
perception.  High speed CW ops often add additional weighting to make it
sound better.

Any suggestions?

73 de Brian/K3KO


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[Darwin, Keith]

I'm confused.  Which key jack are you plugging into?

- Keith N1AS -
- K3 711 -

-----Original Message-----

Out of the blue, the external keyer input to the K3 produces mushy dits
at higher speeds.  

73 de Brian/K3KO
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[alsopb]

KEY IN for external keyer (paddle connected to external keyer, keyer
output keying FET to key in)  ,   PADDLE  connected to paddle input for
internal keyer.  

73 de Brian/K3KO

Darwin, Keith wrote:

>I'm confused.  Which key jack are you plugging into?
>
>- Keith N1AS -
>- K3 711 -
>
>-----Original Message-----
>
>Out of the blue, the external keyer input to the K3 produces mushy dits
>at higher speeds.  
>
>73 de Brian/K3KO
>_______________________________________________
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>Post to: [hidden email]
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>
>  
>

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[Darwin, Keith]

OK that's what I thought.  I think about the KEY IN as the input for
bugs & straight keys and was slightly confused by calling it the
external keyer input :-)

Do you have a bug you can try on that input?

- Keith N1AS -
- K3 711 -

-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of Brian Alsop
Sent: Friday, January 16, 2009 8:13 AM
To: [hidden email]
Subject: Re: [Elecraft] K3- external keyer problems

KEY IN for external keyer (paddle connected to external keyer, keyer
output keying FET to key in)  ,   PADDLE  connected to paddle input for
internal keyer.  

73 de Brian/K3KO

Darwin, Keith wrote:

>I'm confused.  Which key jack are you plugging into?
>
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[alsopb]

Hi Keith,

Unfortunately no bug.  

Now that you mention it, it kind of sounds like a bug when one holds the
dit side down for a long time.   After a number of dots, each gets to
sound longer and longer and more slurred.

For what it is worth,  the computer interface to KEY in uses an NPN
transistor.  The keyer uses a 2n7000 FET.  The FET on state has a really
low voltage drop.  K3  Key terminals have an open circuit voltage of 4.7
V (would have expected closer to 5).   The K3 displays a power-in
voltage of 13.7V.     Have removed all connections to the K3 but
earphones and KEY.   Problem does not go away.

Wierd.

73 de Brian/K3KO

Darwin, Keith wrote:

>OK that's what I thought.  I think about the KEY IN as the input for
>bugs & straight keys and was slightly confused by calling it the
>external keyer input :-)
>
>Do you have a bug you can try on that input?
>
>- Keith N1AS -
>- K3 711 -
>
>-----Original Message-----
>From: [hidden email]
>[mailto:[hidden email]] On Behalf Of Brian Alsop
>Sent: Friday, January 16, 2009 8:13 AM
>To: [hidden email]
>Subject: Re: [Elecraft] K3- external keyer problems
>
>KEY IN for external keyer (paddle connected to external keyer, keyer
>output keying FET to key in)  ,   PADDLE  connected to paddle input for
>internal keyer.  
>
>73 de Brian/K3KO
>
>Darwin, Keith wrote:
>
>  
>
>>I'm confused.  Which key jack are you plugging into?
>>
>>    
>>
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>Elecraft mailing list
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>Subscriber Info (Addr. Change, sub, unsub etc.):
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>
>Help: http://mailman.qth.net/subscribers.htm
>Elecraft web page: http://www.elecraft.com
>
>  
>

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[Don Wilhelm-4]

Brian,

At the KEY input to the K3, it is the low level voltage that is
important, not the high level.  My guess is that your external keyer is
not going to a low enough level to fully discharge the .001 capacitor
that is on the key in line inside the K3.
Do your keyers have a resistor between the keying output line and the
K3?  If so, that could cause slow keying.
It would be best to evaluate the low level during a string of dots with
a DC input on an oscilloscope to see if the low level shifts after a
couple dots.  If it does look for any cause of resistance (or added
capacitance) between the keying driver and the K3 input.

73,
Don W3FPR

Brian Alsop wrote:

> Hi Keith,
>
> Unfortunately no bug.  
>
> Now that you mention it, it kind of sounds like a bug when one holds the
> dit side down for a long time.   After a number of dots, each gets to
> sound longer and longer and more slurred.
>
> For what it is worth,  the computer interface to KEY in uses an NPN
> transistor.  The keyer uses a 2n7000 FET.  The FET on state has a really
> low voltage drop.  K3  Key terminals have an open circuit voltage of 4.7
> V (would have expected closer to 5).   The K3 displays a power-in
> voltage of 13.7V.     Have removed all connections to the K3 but
> earphones and KEY.   Problem does not go away.
>
> Wierd.
>
> 73 de Brian/K3KO
>  
>

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