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Key Out jack

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N4ZR

Key Out jack

I am trying to use the Key Out jack on my K3 to key a small relay to
protect my SDR from RF. The 12V@40 ma is well within the stated rating
of the jack, but to my surprise it does not work. Measuring with an
analog multimeter, the jack appears to be shorted all the time, and also
to have a very small DC voltage on it. I don't have a schematic for the
radio, so I'm stumped. Is this a function of the way I'm measuring, or...?

--

73, Pete N4ZR
Check out the Reverse Beacon Network
at <http://reversebeacon.net>, now
spotting RTTY activity worldwide.
For spots, please use your favorite
"retail" DX cluster.

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Don Wilhelm

Re: Key Out jack

Pete,

As mentioned by others, the K3(S) KEYOUT jack does not produce any
voltage - the voltage must be produced by another source (sufficient to
power the relay).

One method to check the K3 KEYOUT is to use your Ohmmeter. stick the
red probe into the center of the jack and the other probe to the shell.
It should read a very high resistance, even infinity (same as your
ohmmeter reads with the probes attached to nothing) during receive, and
then go to a very low value (close to zero ohms) during TUNE or Transmit.
If it does not do that, you may have a bad HEXFET driver for the KEYOUT
line.

73,
Don W3FPR

On 10/13/2017 9:33 AM, N4ZR wrote:
> I am trying to use the Key Out jack on my K3 to key a small relay to
> protect my SDR from RF. The 12V@40 ma is well within the stated rating
> of the jack, but to my surprise it does not work. Measuring with an
> analog multimeter, the jack appears to be shorted all the time, and also
> to have a very small DC voltage on it. I don't have a schematic for the
> radio, so I'm stumped. Is this a function of the way I'm measuring, or...?
>
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k6dgw

Re: Key Out jack

Related question: Does KEY OUT essentially follow the TX state? IAW,
if PTT or VOX is asserted, it also asserts? If so, I guess that means
that it follows the keying when in QSK? It's a real PITA to get to the
back of my K3 right now or I'd check it myself.

73,

Fred ["Skip"] K6DGW
Sparks NV DM09dn
Washoe County

On 10/13/2017 2:47 PM, Don Wilhelm wrote:

> Pete,
>
> As mentioned by others, the K3(S) KEYOUT jack does not produce any
> voltage - the voltage must be produced by another source (sufficient
> to power the relay).
>
> One method to check the K3 KEYOUT is to use your Ohmmeter. stick the
> red probe into the center of the jack and the other probe to the shell.
> It should read a very high resistance, even infinity (same as your
> ohmmeter reads with the probes attached to nothing) during receive,
> and then go to a very low value (close to zero ohms) during TUNE or
> Transmit.
> If it does not do that, you may have a bad HEXFET driver for the
> KEYOUT line.
>
> 73,
> Don W3FPR
>
> On 10/13/2017 9:33 AM, N4ZR wrote:
>> I am trying to use the Key Out jack on my K3 to key a small relay to
>> protect my SDR from RF. The 12V@40 ma is well within the stated
>> rating of the jack, but to my surprise it does not work. Measuring
>> with an analog multimeter, the jack appears to be shorted all the
>> time, and also to have a very small DC voltage on it. I don't have a
>> schematic for the radio, so I'm stumped. Is this a function of the
>> way I'm measuring, or...?
>>
> ______________________________________________________________
> 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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Don Wilhelm

Re: Key Out jack

Skip,

Yes, it does follow the keying when in QSK. If it did not, the KPA500
would not follow the K3(s) in QSK mode (the KPA500 connection uses the
KEYOUT-LP from the ACC connector).
The T/R switching is all electronic and can be quite fast.

If the amplifier uses relay switching, the relay may not be able to
follow the K3(S).

73,
Don W3FPR

On 10/13/2017 6:02 PM, Fred Jensen wrote:
> Related question: Does KEY OUT essentially follow the TX state? IAW,
> if PTT or VOX is asserted, it also asserts? If so, I guess that means
> that it follows the keying when in QSK? It's a real PITA to get to the
> back of my K3 right now or I'd check it myself.
>
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Jim Rhodes-2

Re: Key Out jack

There is however an adjustable delay. Default 8 ms, which can be adjusted
with TX DLY in the CONFIG menu.

On Fri, Oct 13, 2017 at 5:21 PM, Don Wilhelm <[hidden email]> wrote:

> Skip,
>
> Yes, it does follow the keying when in QSK. If it did not, the KPA500
> would not follow the K3(s) in QSK mode (the KPA500 connection uses the
> KEYOUT-LP from the ACC connector).
> The T/R switching is all electronic and can be quite fast.
>
> If the amplifier uses relay switching, the relay may not be able to follow
> the K3(S).
>
> 73,
> Don W3FPR
>
> On 10/13/2017 6:02 PM, Fred Jensen wrote:
>
>> Related question: Does KEY OUT essentially follow the TX state? IAW, if
>> PTT or VOX is asserted, it also asserts? If so, I guess that means that it
>> follows the keying when in QSK? It's a real PITA to get to the back of my
>> K3 right now or I'd check it myself.
>>
>> ______________________________________________________________
> 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]
>

--
Jim K0XU
[hidden email]
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Clay Autery-2

Re: Key Out jack

In reply to this post by N4ZR

K3 Schematics: http://www.elecraft.com/manual/K3_Schematics_Jun_2010.pdf
K3S Schematics:
http://www.elecraft.com/manual/E740323%20K3s%20Schematic%20Files.pdf

______________________
Clay Autery, KY5G
MONTAC Enterprises
(318) 518-1389

On 10/13/2017 8:33 AM, N4ZR wrote:

> I am trying to use the Key Out jack on my K3 to key a small relay to
> protect my SDR from RF. The 12V@40 ma is well within the stated
> rating of the jack, but to my surprise it does not work. Measuring
> with an analog multimeter, the jack appears to be shorted all the
> time, and also to have a very small DC voltage on it. I don't have a
> schematic for the radio, so I'm stumped. Is this a function of the
> way I'm measuring, or...?
>
> --
>
> 73, Pete N4ZR
> Check out the Reverse Beacon Network
> at <http://reversebeacon.net>, now
> spotting RTTY activity worldwide.
> For spots, please use your favorite
> "retail" DX cluster.