K3 Keying Up For A Split Second When Power Button Is Pushed

[-.-. --.-N3TU -.-. --.-]

Is it normal for the K3 to key up right away for a split second when turned on. I have a Drake L4B with a soft key behind the radio. If by accident the amp is out of the  stand-by mode and you turn on the K3, it will key the amp for a split second. Is this normal? Don't get me wrong, I try to put it in standby but every now and then I'll forget.

[W8JI]

<<<Is it normal for the K3 to key up right away for a split
second when turned
on. I have a Drake L4B with a soft key behind the radio. If
by accident the
amp is out of the  stand-by mode and you turn on the K3, it
will key the amp
for a split second. Is this normal? Don't get me wrong, I
try to put it in
standby but every now and then I'll forget. >>>

That's normal behavior for the K3.

I don't like it either, but a properly designed step-start
should still be OK with just the quiescent current of the PA
tubes so long as RF is not applied. The only problem would
come in when the step-start and the radio both have issues.
If the step-start isn't planned well, and blows a fuse or a
resistor when starting under quiescent current loads, then
the radio doing closing the relay line at power-on  becomes
a problem.

As a suggestion you could easily build a time-delay start up
for the amp, which it should have if simply closing the
relay control line at amplifier power-on causes damage.
You'd have to add a small relay and wire it in series with
the relay control jack.

My amplifiers start just fine at quiescent loads, so I don't
worry (although what you observe annoys me too and I can see
where it could cause step-start damage in some systems).

73, Tom





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[Gary Bartlett VE1RGB]

It took me a copy of tries to make my point to get Wayne to make the change,
but at V3.10 of the firmware, he made the following addition feature
available:

CW VOX OFF BY DEFAULT ON POWER-UP: Some stations using PC control may
inadvertently key the K3 in CW mode on power-up if VOX CW is in effect. If
this is an issue at your station, locate the CONFIG:CW WGHT menu entry and
tap '4', changing VOX NOR to AUTO  OFF. This will make CW VOX default to OFF
when the K3 is turned on.

That way, if a person accidentally forgets to turn VOX OFF when he shuts the
radio down, it will automatically turn itself OFF next time you turn the K3
on.  On my radio, if I want to transmit after I turn the radio ON, I have to
re-select VOX ON again.  

73,
Gary, VE1RGB

-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of -.-. --.-N3TU -.-.
--.-
Sent: April 1, 2010 3:34 AM
To: [hidden email]
Subject: [Elecraft] K3 Keying Up For A Split Second When Power Button Is
Pushed


Is it normal for the K3 to key up right away for a split second when turned
on. I have a Drake L4B with a soft key behind the radio. If by accident the
amp is out of the  stand-by mode and you turn on the K3, it will key the amp
for a split second. Is this normal? Don't get me wrong, I try to put it in
standby but every now and then I'll forget.
--
View this message in context:
http://n2.nabble.com/K3-Keying-Up-For-A-Split-Second-When-Power-Button-Is-Pu
shed-tp4835488p4835488.html
Sent from the [K3] mailing list archive at Nabble.com.
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[Guy, K2AV]

I'm not sure I'm understanding your problem.  Are you talking about
having the amp on before the K3 is powered up?  Are you leaving the
amp with filaments on during periods while the K3 has been powered
off?  Powering on the K3 and waiting a second to power on the amp
would seem to remove the issue with the K3 getting its states in order
on power-up.

73, Guy

On Thu, Apr 1, 2010 at 2:34 AM, -.-.  --.-N3TU -.-.  --.-
<[hidden email]> wrote:

>
> Is it normal for the K3 to key up right away for a split second when turned
> on. I have a Drake L4B with a soft key behind the radio. If by accident the
> amp is out of the  stand-by mode and you turn on the K3, it will key the amp
> for a split second. Is this normal? Don't get me wrong, I try to put it in
> standby but every now and then I'll forget.
> --
> View this message in context: http://n2.nabble.com/K3-Keying-Up-For-A-Split-Second-When-Power-Button-Is-Pushed-tp4835488p4835488.html
> Sent from the [K3] mailing list archive at Nabble.com.
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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> Post: mailto:[hidden email]
>
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> Please help support this email list: http://www.qsl.net/donate.html
>

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[W8JI]

<<<
It took me a copy of tries to make my point to get Wayne to
make the change,
but at V3.10 of the firmware, he made the following addition
feature
available:

CW VOX OFF BY DEFAULT ON POWER-UP: Some stations using PC
control may
inadvertently key the K3 in CW mode on power-up if VOX CW is
in effect. If
this is an issue at your station, locate the CONFIG:CW WGHT
menu entry and
tap '4', changing VOX NOR to AUTO  OFF. This will make CW
VOX default to OFF
when the K3 is turned on.

That way, if a person accidentally forgets to turn VOX OFF
when he shuts the
radio down, it will automatically turn itself OFF next time
you turn the K3
on.  On my radio, if I want to transmit after I turn the
radio ON, I have to
re-select VOX ON again.>>>

This does not solve or change the problem.

The problem is, when the radio boots up, the amplifier relay
control line is pulled low during the very early part of the
power up. This happens in any mode with any VOX setting.

The situation this creates is if an external power amp with
step-start is connected, some amplifiers go into quiescent
current (TX relay closure) when the radio is powering up.
This false triggering of the PA relay can cause an amplifier
inrush circuit to be damaged.

For example the Drake L4B would would try to draw about 500
additional watts through the step-start if the TX line was
held low on amplifier power up if the radio is booting at
the same time. Seeing all my TX indicators illuminate and
hearing relays click when I power up the K3 is more of an
annoyance to me, because my amplifers are designed to be in
any keying state on power up without damage. On some
amplifiers though, it can actually hurt components if they
are held in TX mode while powering up.

I think the burden of design fault is in the amplifier,
there should be no relay line state that causes or allows
damage on power up, but the radio boot behavior is a little
annoying. It might be some I/O areas like the relay control
just fault into a TX mode before the system is booted, and
there may be no way around that.

73 Tom


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