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K3 key-out jack - configuration needed?

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Oliver Dröse

K3 key-out jack - configuration needed?

Hi guys,

preparing for the autumn contest season I thought to do some cable work today.
Made up a cable to key the amplifier and wanted to use the key-out jack therefor
(only need to sink 13,8 V / 60 mA so should work perfectly well). But the amp
isn't keying. So I measured the RCA jack and unkeyed I can measure infinite
resistance as it should be the case but if I ptt the radio no change on the RCA
jack?! Should be around zero then so no keying there.

Checked the manual but couldn't find anything related to configuration of that
jack, seems it should be always working, right? Any ideas why it is not?

Checked the LP key-out on the ACC connector and that is working properly (but
not enough for the amp, ofcourse, only measured there for verification the radio
is really keying out, hi).

Can anybody help?

TIA & 73, Olli - DH8BQA

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Don Wilhelm-4

Re: K3 key-out jack - configuration needed?

Olli,

The Key Out and the ACC connector Keyout-LP are developed from the same
internal signal, but the driving transistors are different for each.
The Key Out jack is driven by Q5 and Q3 on the RF Board, and you will
find your problem associated with one of those transistors. See the
schematic for the RF board at the top left of sheet 1. Check R4 as well
- the gate of Q3 should go to a high level during transmit (use TX test).

73,
Don W3FPR

On 10/10/2010 10:31 AM, Oliver "Olli" Dröse wrote:

> Hi guys,
>
> preparing for the autumn contest season I thought to do some cable work today.
> Made up a cable to key the amplifier and wanted to use the key-out jack therefor
> (only need to sink 13,8 V / 60 mA so should work perfectly well). But the amp
> isn't keying. So I measured the RCA jack and unkeyed I can measure infinite
> resistance as it should be the case but if I ptt the radio no change on the RCA
> jack?! Should be around zero then so no keying there.
>
> Checked the manual but couldn't find anything related to configuration of that
> jack, seems it should be always working, right? Any ideas why it is not?
>
> Checked the LP key-out on the ACC connector and that is working properly (but
> not enough for the amp, ofcourse, only measured there for verification the radio
> is really keying out, hi).
>
> Can anybody help?
>
> TIA& 73, Olli - DH8BQA
>
>
>
> ______________________________________________________________
> 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
>

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Oliver Dröse

Re: K3 key-out jack - configuration needed?

Hi Don,

many thanks for your advice. Just opened up the K3, located Q3 and Q5 and
measured there directly. Everything as it should be, 13 V bias to the gates
during TX, Drain switching to ground, everything as expected. Uh? Same
measurements at the RCA jack from the PCB and everything fine. Measured again
from the outside and ... everything fine?! Connecting the cable, PA is
switching. Closing the cover and putting on the screws and still everything
fine?! I have no clue why it's working perfectly now and didn't before ...
*scratching head*

Oh well, maybe my K3 simply wanted somebody to look into it's beautiful inards
again. ;-))

Andyway, thanks again for your help. Must be magic emails in this case. ;-))

73, Olli - DH8BQA

----- Original Message -----
From: "Don Wilhelm" <[hidden email]>
To: ""Oliver \"Olli\" Dröse"" <[hidden email]>
Cc: <[hidden email]>
Sent: Sunday, October 10, 2010 6:32 PM
Subject: Re: [Elecraft] K3 key-out jack - configuration needed?

> Olli,
>
> The Key Out and the ACC connector Keyout-LP are developed from the same
> internal signal, but the driving transistors are different for each.
> The Key Out jack is driven by Q5 and Q3 on the RF Board, and you will
> find your problem associated with one of those transistors. See the
> schematic for the RF board at the top left of sheet 1. Check R4 as well
> - the gate of Q3 should go to a high level during transmit (use TX test).
>
> 73,
> Don W3FPR
>
> On 10/10/2010 10:31 AM, Oliver "Olli" Dröse wrote:
>> Hi guys,
>>
>> preparing for the autumn contest season I thought to do some cable work
>> today.
>> Made up a cable to key the amplifier and wanted to use the key-out jack
>> therefor
>> (only need to sink 13,8 V / 60 mA so should work perfectly well). But the amp
>> isn't keying. So I measured the RCA jack and unkeyed I can measure infinite
>> resistance as it should be the case but if I ptt the radio no change on the
>> RCA
>> jack?! Should be around zero then so no keying there.
>>
>> Checked the manual but couldn't find anything related to configuration of
>> that
>> jack, seems it should be always working, right? Any ideas why it is not?
>>
>> Checked the LP key-out on the ACC connector and that is working properly (but
>> not enough for the amp, ofcourse, only measured there for verification the
>> radio
>> is really keying out, hi).
>>
>> Can anybody help?
>>
>> TIA& 73, Olli - DH8BQA
>>
>>
>>
>> ______________________________________________________________
>> 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
>>

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Oliver Dröse

Re: K3 key-out jack - configuration needed?

In reply to this post by Oliver Dröse

Hi James,

you don't need to connect an outside pull-up (only if you want to measure
voltages, so you are basically right as well, depending on what/how you want to
measure ;-)). The transistor is used as a simple electronic switch here thus
when getting bias on it's gate it will switch source (connected to ground)
through to the gate (also groundlevel then, that's why you can simply measure
for 0 ohm resistance between drain and chassis when keyed). If no bias then
infinite ohms at drain.

Anyway, thanks for your assistance and advices! This is what I love about
Elecraft and their email reflector. ;-))

73, Olli - DH8BQA

----- Original Message -----
From: "JAMES ROGERS" <[hidden email]>
To: "Oliver "Olli" Dröse" <[hidden email]>
Sent: Sunday, October 10, 2010 6:29 PM
Subject: Re: [Elecraft] K3 key-out jack - configuration needed?

Oliver, it is a MOSFET, IRF630 and you may be right, but I would not
expect to see any change until I provided a voltage source to the Key
Out line. So, if it was me I would do the "pull up" resistor test I
described earlier just to be on the safe side. It appears from the
schematic that it is switched by the 7R line. K3 schematics, RF Board
sheet 1 of 4. There is no drain voltage applied to the IRF630 so that
will have to be supplied externally.

Jim, W4ATK
On Oct 10, 2010, at 11:05 AM, Oliver Olli Dröse wrote:

> Hi James,
>
> well, resistance check should work to my mind at least when keying
> the radio. Unkeyed it is an open collector as I understood (thus
> infinite) and keyed the keying transistor is switching to ground so
> then I should measure 0 ohm (or nearly 0, the low-power key-out port
> hast 446 ohm keyed).
>
> Anyway, ofcourse tried with the amp before and as that was not keyed
> I pulled everything out to do the measurements. The amp itself as
> well as the cable is okay. As soon as I put the cable connected to
> the amp to ground /chassis of K3) everything's switching as
> expected. It is just that the RCA jack has no keying signal. :-((
>
> 73, Olli - DH8BQA
>
>
>
> ----- Original Message ----- From: "JAMES ROGERS"
> <[hidden email]>
> To: "Oliver Olli Dröse" <[hidden email]>
> Sent: Sunday, October 10, 2010 5:28 PM
> Subject: Re: [Elecraft] K3 key-out jack - configuration needed?
>
>
> Oliver,
> Key Out is not a set of dry contacts and thus measuring with a VOM
> for resistance would be a bit problematic. You could use a "pull up"
> resistor (2K or so) from the Key Out line to a power supply, say 12V.
> Put your VOM on an appropriate voltage scale to measure the voltage at
> the junction of the pull up resistor and the Key Out line and the
> voltage to go to near 0 when PTT is activated. Or you could just hook
> up you amp and see if it is keyed when PTT is activated. According to
> the book it will handle up to +200VDC at 5A.
>
> Jim, W4ATK
>
> On Oct 10, 2010, at 9:31 AM, Oliver Olli Dröse wrote:
>
>> Hi guys,
>>
>> preparing for the autumn contest season I thought to do some cable
>> work today.
>> Made up a cable to key the amplifier and wanted to use the key-out
>> jack therefor
>> (only need to sink 13,8 V / 60 mA so should work perfectly well).
>> But the amp
>> isn't keying. So I measured the RCA jack and unkeyed I can measure
>> infinite
>> resistance as it should be the case but if I ptt the radio no change
>> on the RCA
>> jack?! Should be around zero then so no keying there.
>>
>> Checked the manual but couldn't find anything related to
>> configuration of that
>> jack, seems it should be always working, right? Any ideas why it is
>> not?
>>
>> Checked the LP key-out on the ACC connector and that is working
>> properly (but
>> not enough for the amp, ofcourse, only measured there for
>> verification the radio
>> is really keying out, hi).
>>
>> Can anybody help?
>>
>> TIA & 73, Olli - DH8BQA
>>
>>
>>
>> ______________________________________________________________
>> 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
>
>
>
> --------------------------------------------------------------------------------
>
>
>
> Eingehende eMail ist virenfrei.
> Von AVG überprüft - www.avg.de
> Version: 9.0.862 / Virendatenbank: 271.1.1/3187 - Ausgabedatum:
> 10/09/10 20:34:00
>

Guy, K2AV

Re: K3 key-out jack - configuration needed?

In reply to this post by Oliver Dröse

Sometimes Tip/Ring/Sleeve plugs give a false detent and the plug was
not all the way in. Also if a conductor in a cord has broken inside
its insulation, you can get this behavior, including everything
working OK afterwards. Another issue is the tip of an RCA plus not
being quite long enough, or the molding around it keeping it from
being fully inserted. Also RCA chassis jacks are famous for losing
their connection to chassis if a biting lockwasher was not used.

You may wish to construct a replacement cord set and throw away the
wire you are using now.

73, Guy

On Sun, Oct 10, 2010 at 6:06 PM, Oliver "Olli" Dröse <[hidden email]> wrote:

> Hi Don,
>
> many thanks for your advice. Just opened up the K3, located Q3 and Q5 and
> measured there directly. Everything as it should be, 13 V bias to the gates
> during TX, Drain switching to ground, everything as expected. Uh? Same
> measurements at the RCA jack from the PCB and everything fine. Measured again
> from the outside and ... everything fine?! Connecting the cable, PA is
> switching. Closing the cover and putting on the screws and still everything
> fine?! I have no clue why it's working perfectly now and didn't before ...
> *scratching head*
>
> Oh well, maybe my K3 simply wanted somebody to look into it's beautiful inards
> again. ;-))
>
> Andyway, thanks again for your help. Must be magic emails in this case. ;-))
>
> 73, Olli - DH8BQA
>
>
>
> ----- Original Message -----
> From: "Don Wilhelm" <[hidden email]>
> To: ""Oliver \"Olli\" Dröse"" <[hidden email]>
> Cc: <[hidden email]>
> Sent: Sunday, October 10, 2010 6:32 PM
> Subject: Re: [Elecraft] K3 key-out jack - configuration needed?
>
>
>> Olli,
>>
>> The Key Out and the ACC connector Keyout-LP are developed from the same
>> internal signal, but the driving transistors are different for each.
>> The Key Out jack is driven by Q5 and Q3 on the RF Board, and you will
>> find your problem associated with one of those transistors. See the
>> schematic for the RF board at the top left of sheet 1. Check R4 as well
>> - the gate of Q3 should go to a high level during transmit (use TX test).
>>
>> 73,
>> Don W3FPR
>>
>> On 10/10/2010 10:31 AM, Oliver "Olli" Dröse wrote:
>>> Hi guys,
>>>
>>> preparing for the autumn contest season I thought to do some cable work
>>> today.
>>> Made up a cable to key the amplifier and wanted to use the key-out jack
>>> therefor
>>> (only need to sink 13,8 V / 60 mA so should work perfectly well). But the amp
>>> isn't keying. So I measured the RCA jack and unkeyed I can measure infinite
>>> resistance as it should be the case but if I ptt the radio no change on the
>>> RCA
>>> jack?! Should be around zero then so no keying there.
>>>
>>> Checked the manual but couldn't find anything related to configuration of
>>> that
>>> jack, seems it should be always working, right? Any ideas why it is not?
>>>
>>> Checked the LP key-out on the ACC connector and that is working properly (but
>>> not enough for the amp, ofcourse, only measured there for verification the
>>> radio
>>> is really keying out, hi).
>>>
>>> Can anybody help?
>>>
>>> TIA& 73, Olli - DH8BQA
>>>
>>>
>>>
>>> ______________________________________________________________
>>> 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
>>>
>
>
> --------------------------------------------------------------------------------
>
>
>
> Eingehende eMail ist virenfrei.
> Von AVG überprüft - www.avg.de
> Version: 9.0.862 / Virendatenbank: 271.1.1/3187 - Ausgabedatum: 10/09/10
> 20:34:00
>
> ______________________________________________________________
> 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
>