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K3 Key Out line

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Phil Hystad

K3 Key Out line

I noticed from the documentation that the K3 Key out line can handle up to 200 VDC and 5 amps. I assume this means that when the key out is closed that it can handle 5 amps of current.

So, I am curious, what kind of switch mechanism is used for TR switching. Is this an actual relay or is it some kind of transistor switch. I am guessing transistor based switch but this is where I started wondering about the 200 VDC and 5 amp capability thing.

Or, am I totally off base. I am willing to be off base without shame because I really do not know a lot of details of how these things are actually done.

Oh, two more minor decisions on configuration to make and then I order my K3, probably just after Christmas sometime.

phil, K7PEH

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wayne burdick

Re: K3 Key Out line

Administrator

Hi Phil,

Key out is driven by a very rugged N-channel MOSFET.

73,
Wayne
N6KR

On Dec 23, 2009, at 9:01 AM, Phil Hystad wrote:

> I noticed from the documentation that the K3 Key out line can handle
> up to 200 VDC and 5 amps. I assume this means that when the key out
> is closed that it can handle 5 amps of current.
>
> So, I am curious, what kind of switch mechanism is used for TR
> switching. Is this an actual relay or is it some kind of transistor
> switch. I am guessing transistor based switch but this is where I
> started wondering about the 200 VDC and 5 amp capability thing.

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Don Wilhelm-4

Re: K3 Key Out line

In reply to this post by Phil Hystad

Phil,

There is no direct relationship between the KEYOUT line and the T/R
switch in the K3. The T/R switch is fully electronic, no relays to
clack and clatter.

The KEYOUT line goes to ground before the onset of RF - and the delay
can be adjusted in the menu. It is normally used for keying an
amplifier. There is also a Keyout-LP line on the ACC connector that
operates at the same time, but the current capability is only 10 ma.
Yes, KEYOUT can handle up to 200 volts open circuit voltage and 5 amps
of closed (keydown) current.

73,
Don W3FPR

Phil Hystad wrote:

> I noticed from the documentation that the K3 Key out line can handle up to 200 VDC and 5 amps. I assume this means that when the key out is closed that it can handle 5 amps of current.
>
> So, I am curious, what kind of switch mechanism is used for TR switching. Is this an actual relay or is it some kind of transistor switch. I am guessing transistor based switch but this is where I started wondering about the 200 VDC and 5 amp capability thing.
>
> Or, am I totally off base. I am willing to be off base without shame because I really do not know a lot of details of how these things are actually done.
>
> Oh, two more minor decisions on configuration to make and then I order my K3, probably just after Christmas sometime.
>
> phil, K7PEH
>
>

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K1LI

Re: K3 Key Out line

In reply to this post by Phil Hystad

Phil,

You can see the T-R switching circuitry in the schematics available on the
Elecraft web site. Just search for "t-r" and you'll find the circuitry for
both the 10W and 100W PAs.
--
73 -- Brian -- K1LI

On Wed, Dec 23, 2009 at 12:01 PM, Phil Hystad <[hidden email]> wrote:

> I noticed from the documentation that the K3 Key out line can handle up to
> 200 VDC and 5 amps. I assume this means that when the key out is closed
> that it can handle 5 amps of current.
>
> So, I am curious, what kind of switch mechanism is used for TR switching.
> Is this an actual relay or is it some kind of transistor switch. I am
> guessing transistor based switch but this is where I started wondering about
> the 200 VDC and 5 amp capability thing.
>
> Or, am I totally off base. I am willing to be off base without shame
> because I really do not know a lot of details of how these things are
> actually done.
>
> Oh, two more minor decisions on configuration to make and then I order my
> K3, probably just after Christmas sometime.
>
> phil, K7PEH
>
> ______________________________________________________________
> 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
>