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Tuning noise on K2 - 40M

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Dave-Boat Guy

Tuning noise on K2 - 40M

Hi,
I was tuning around on 40M this evening and noticed
some clicks when I tuned from 7119.82 to 7120.00. I
started checking and I noticed this behavior from
about 7050 through 7320...every 10 KHz. If I
disconnect my antenna this problem goes away. The
problem remains if I use the attenuator or change mode
or filter settings. Disabling the AGC or changing
from slow to fast has no effect. This appears to be
only happening on 40M.

Since the problem goes away when I remove the antenna,
I'm wondering if it is due to some mixing product
although it happens even when the band is quiet...but
the antenna is connected.

Any ideas?

Thanks in advance.

Dave

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Geoffrey Mackenzie-Kennedy-2

Re: Tuning noise on K2 - 40M

Dave,

My K2 also produces clicks on 40m which disappear if the antenna is
disconnected or turned away from strong BC stations above 7100 kHz. Running
CAL PLL has not cured the problem, and I have since found the same problem
on 15m. It might exist on other bands but I have not had the time to check.
I have a *suspicion* that strong signals from the antenna / banspass filters
reach the VCO and Reference oscillator area of the RF board by some direct
route, not via the Preamp / attenuator / mixer and momentarily 'upset' the
VCO causing the click. The VCO (VFO) could be upset if some product produced
by multiple mixing attempted to take over control of the loop, sometimes a
problem with locked loops. But I cannot confirm this yet due to lack of time
at the moment.

73,
Geoff
GM4ESD

----- Original Message -----
From: "Dave-Boat Guy" <[hidden email]>
To: <[hidden email]>
Sent: Monday, February 12, 2007 1:58 AM
Subject: [Elecraft] Tuning noise on K2 - 40M

> Hi,
> I was tuning around on 40M this evening and noticed
> some clicks when I tuned from 7119.82 to 7120.00. I
> started checking and I noticed this behavior from
> about 7050 through 7320...every 10 KHz. If I
> disconnect my antenna this problem goes away. The
> problem remains if I use the attenuator or change mode
> or filter settings. Disabling the AGC or changing
> from slow to fast has no effect. This appears to be
> only happening on 40M.
>
> Since the problem goes away when I remove the antenna,
> I'm wondering if it is due to some mixing product
> although it happens even when the band is quiet...but
> the antenna is connected.
>
> Any ideas?
>
> Thanks in advance.
>
> Dave

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w9cf

Re: Tuning noise on K2 - 40M

In reply to this post by Dave-Boat Guy

I think this is the known "feature" described by Wayne in:
http://www.ac6rm.net/mailarchive/html/elecraft-list/2000-03/msg01007.html

73 Kevin w9cf

>My K2 also produces clicks on 40m which disappear if the antenna
>is disconnected or turned away from strong BC stations above 7100
>kHz. Running CAL PLL has not cured the problem, and I have since found
>the same problem on 15m. It might exist on other bands but I have not
>had the time to check. I have a *suspicion* that strong signals from the
>antenna / banspass filters reach the VCO and Reference oscillator area
>of the RF board by some direct route, not via the Preamp / attenuator /
>mixer and momentarily 'upset' the VCO causing the click. The VCO (VFO)
>could be upset if some product produced by multiple mixing attempted to
>take over control of the loop, sometimes a problem with locked loops. But
>I cannot confirm this yet due to lack of time at the moment.
>
>73,
>Geoff
>GM4ESD

Geoffrey Mackenzie-Kennedy-2

Re: Tuning noise on K2 - 40M

Many thanks for the lead. Strangely the frequency separation between
adjacent clicks seems to be related to the number, separation and strengths
of strong received signals. Also on occasion when tuning through a 40m BC
station whose received carrier level is in the region of -10dbm, the
receiver will lock onto the BC signal and not let go until it has been tuned
further a few kHz, typical is approx 3 kHz and always (I think) down in
frequency, then a 'plop'. This is why I have the *suspicion* previously
mentioned.

73,
Geoff
GM4ESD

----- Original Message -----
From: "Kevin Schmidt" <[hidden email]>
To: <[hidden email]>
Sent: Monday, February 12, 2007 9:06 PM
Subject: Re: [Elecraft] Tuning noise on K2 - 40M

>
> I think this is the known "feature" described by Wayne in:
> http://www.ac6rm.net/mailarchive/html/elecraft-list/2000-03/msg01007.html
>
> 73 Kevin w9cf
>
>>My K2 also produces clicks on 40m which disappear if the antenna
>>is disconnected or turned away from strong BC stations above 7100
>>kHz. Running CAL PLL has not cured the problem, and I have since found
>>the same problem on 15m. It might exist on other bands but I have not
>>had the time to check. I have a *suspicion* that strong signals from the
>>antenna / banspass filters reach the VCO and Reference oscillator area
>>of the RF board by some direct route, not via the Preamp / attenuator /
>>mixer and momentarily 'upset' the VCO causing the click. The VCO (VFO)
>>could be upset if some product produced by multiple mixing attempted to
>>take over control of the loop, sometimes a problem with locked loops. But
>>I cannot confirm this yet due to lack of time at the moment.
>>
>>73,
>>Geoff
>>GM4ESD