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K3_P3_160_CW

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K5DNL

K3_P3_160_CW

Wayne,

While working 160M DX last winter I noticed that when I
Switch from RX antenna (Beverage) and back to TX antenna
That the base line (Noise floor) on the P3 was about 2 S unites
Less than when I changes to the RX antenna.

With the default antenna ( TX antenna ) PreAmp = off and ATT = ON
Switch to RX antenna (with the preamp off) turn the preamp on and switch back to normal antenna.
Now if you switch the preamp on and off, the base line will return to normal.
Hard for me to explain.

Thanks Ken K5DNL

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Alan Bloom

Re: K3_P3_160_CW

The P3 keeps track of the preamp/attenuator status reported by the K3 so
that the dBm or S-unit display reads accurately. That can lead to some
non-intuitive behavior. For example, turning on the K3 preamp typically
makes the noise level on the P3 go down rather than up. The reason is
that the P3 is turning down its gain to compensate for the increased
gain in the K3.

However this doesn't always work correctly when switching the RX antenna
on the K3. Currently the K3 does not send an update to the P3 if
switching antennas causes the preamp or attenuator status to change.
This is on Wayne's bug list.

Alan N1AL

On Sun, 2011-04-17 at 12:21 -0700, Ken Roberson wrote:

> Wayne,
>
> While working 160M DX last winter I noticed that when I
> Switch from RX antenna (Beverage) and back to TX antenna
> That the base line (Noise floor) on the P3 was about 2 S unites
> Less than when I changes to the RX antenna.
>
> With the default antenna ( TX antenna ) PreAmp = off and ATT = ON
> Switch to RX antenna (with the preamp off) turn the preamp on and switch back to normal antenna.
> Now if you switch the preamp on and off, the base line will return to normal.
> Hard for me to explain.
>
> Thanks Ken K5DNL
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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>
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> Please help support this email list: http://www.qsl.net/donate.html
>

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K5DNL

Re: K3_P3_160_CW

Alan,

Thank you for info , I knew it was a firmware bug ,did not know that it had been reported.

Sorry for the bandwidth .

73 Ken K5DNL
-----------------------------------------------------------

--- On Sun, 4/17/11, Alan Bloom <[hidden email]> wrote:

> From: Alan Bloom <[hidden email]>
> Subject: Re: [Elecraft] K3_P3_160_CW
> To: "Ken Roberson" <[hidden email]>
> Cc: "Elecraft Elecraft" <[hidden email]>
> Date: Sunday, April 17, 2011, 11:20 PM
> The P3 keeps track of the
> preamp/attenuator status reported by the K3 so
> that the dBm or S-unit display reads accurately. That
> can lead to some
> non-intuitive behavior. For example, turning on the
> K3 preamp typically
> makes the noise level on the P3 go down rather than
> up. The reason is
> that the P3 is turning down its gain to compensate for the
> increased
> gain in the K3.
>
> However this doesn't always work correctly when switching
> the RX antenna
> on the K3. Currently the K3 does not send an update
> to the P3 if
> switching antennas causes the preamp or attenuator status
> to change.
> This is on Wayne's bug list.
>
> Alan N1AL
>
>
> On Sun, 2011-04-17 at 12:21 -0700, Ken Roberson wrote:
> > Wayne,
> >
> > While working 160M DX last winter I noticed that when
> I
> > Switch from RX antenna (Beverage) and back to TX
> antenna
> > That the base line (Noise floor) on the P3 was about 2
> S unites
> > Less than when I changes to the RX antenna.
> >
> > With the default antenna ( TX antenna ) PreAmp = off
> and ATT = ON
> > Switch to RX antenna (with the preamp off) turn the
> preamp on and switch back to normal antenna.
> > Now if you switch the preamp on and off, the base line
> will return to normal.
> > Hard for me to explain.
> >
> > Thanks Ken K5DNL
> >
> >
> ______________________________________________________________
> > 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
> >
>
>
>

Don Wilhelm-4

Re: K3_P3_160_CW

In reply to this post by K5DNL

Ken,

Maybe I'm missing something, but I would expect the noise floor to drop
on a receiving antenna - assuming the RX antenna is a lower noise
antenna than the transmit antenna - you are looking at the atmospheric
noise and not the receiver noise floor.

73,
Don W3FPR

On 4/17/2011 3:21 PM, Ken Roberson wrote:

gm3sek

Re: K3_P3_160_CW

In reply to this post by Alan Bloom

Alan Bloom wrote:

>The P3 keeps track of the preamp/attenuator status reported by the K3
>so that the dBm or S-unit display reads accurately. That can lead to
>some non-intuitive behavior. For example, turning on the K3 preamp
>typically makes the noise level on the P3 go down rather than up. The
>reason is that the P3 is turning down its gain to compensate for the
>increased gain in the K3.
>
>However this doesn't always work correctly when switching the RX
>antenna on the K3. Currently the K3 does not send an update to the P3
>if switching antennas causes the preamp or attenuator status to change.
>This is on Wayne's bug list.
>

From the wider viewpoint of optimizing the dynamic range on each band,
it would be very helpful if the required preamp/attenuator settings were
saved separately for each antenna input. Those settings would then be
'applied' to whichever receiver(s) are using that input.

Don has just shown exactly why this is needed, because it's the
*antennas* that create the variations in signal levels and background
noise.

--

73 from Ian GM3SEK
http://www.ifwtech.co.uk/g3sek
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Scott Ellington

Re: K3_P3_160_CW

In reply to this post by Alan Bloom

Another thing for Wayne's list, if it isn't already there:

When the sub-receiver is switched on, the P3 does not compensate for the 3 dB splitter loss.

Scott K9MA

On Apr 17, 2011, at 11:20 PM, Alan Bloom wrote:

> However this doesn't always work correctly when switching the RX antenna
> on the K3. Currently the K3 does not send an update to the P3 if
> switching antennas causes the preamp or attenuator status to change.
> This is on Wayne's bug list.

Scott Ellington
Madison, Wisconsin
USA

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Joe Subich, W4TV-4

Re: K3_P3_160_CW

> Another thing for Wayne's list,

That one isn't Wayne's list ... the K3 already reports the
second receiver status. It's something that Al needs to
handle in the P3.

73,

... Joe, W4TV

On 4/18/2011 11:10 AM, Scott Ellington wrote:

> Another thing for Wayne's list, if it isn't already there:
>
> When the sub-receiver is switched on, the P3 does not compensate for the 3 dB splitter loss.
>
> Scott K9MA
>
>
>
> On Apr 17, 2011, at 11:20 PM, Alan Bloom wrote:
>
>> However this doesn't always work correctly when switching the RX antenna
>> on the K3. Currently the K3 does not send an update to the P3 if
>> switching antennas causes the preamp or attenuator status to change.
>> This is on Wayne's bug list.
>
> Scott Ellington
> Madison, Wisconsin
> USA
>
>
>
> ______________________________________________________________
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>
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>