Elecraft

K3 Data Mode Transmit Issue

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Joe Barger

K3 Data Mode Transmit Issue

The setup:

K3 with latest firmware.

Main Filters installed:
F2 2.7 KHz
F4 500 Hz
F5 200 Hz

F2 configured for all RX/TX modes
F4 and F5 configured for CW and Data RX

Configuration:
TX Test (no RF out)
Audio fed into line in (but no difference with mic input)
Line in set for "4 bars" ALC (but doesn't seem to make any difference how many bars)
Data Mode selected
Monitor turned up to comfortable level.

If F5 is selected as the RX filter, all is well. But if either of the other filters is selected for RX and tones are transmitted, the tones have an audible "tick" with a frequency of (I'm guessing) around 40 Hz on top of the tone. The frequency of the tick changes slightly as the frequency of the tone changes. Audio input levels don't change the tick until the audio level approaches 0, then the ticks go away. Modifying shift or bandwidth doesn't affect the tick. Audio input signal is clean. Change the RX filter back to F5 and all is well again. Switch to USB and all is well with any filter.

My guess is there is something funny (a bug?) with the selection of the Data TX filter.

Anyone else have this problem? Any ideas?

Thanks

Joe N6KK

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Joe Barger

Re: K3 Data Mode Transmit Issue

I had a chance to do a little more investigating today.

In summary, in data mode "AFSK A" and AFSK TX: OFF, F5 had no ticks (F2 and
F4 had ticks). With AFSK TX: ON, no filter had ticks.

With the data mode in "DATA A", AFSK TX made no difference if it was on or
off. F4 and F5 had no ticks, but F2 had the ticks.

I'm not sure AFSK TX has fixed the root cause of the problem it was designed
for. If the noise that the AFSK TX filter was designed to remove is
actually caused by "RFI, ground loops, low AF level, ... ", why are there
combinations of main filters on receive that don't display the ticks whether
the AFSK TX filter is on or off? F5 never had the ticks on transmit. I
believe that a single TX filter (F2 in my case) is used for transmit, so why
do the various choices of RX filters affect the transmit "ticks"? Of
course, the "ticks" I'm hearing may not be related to the other reported
noise sources at all, but there still seems to be a problem.

Can anyone else reproduce these results? Any thoughts Lyle?

Joe N6KK

----- Original Message -----
From: "Joe Barger" <[hidden email]>
To: <[hidden email]>
Sent: Wednesday, March 11, 2009 5:45 PM
Subject: [Elecraft] K3 Data Mode Transmit Issue

> The setup:
>
> K3 with latest firmware.
>
> Main Filters installed:
> F2 2.7 KHz
> F4 500 Hz
> F5 200 Hz
>
> F2 configured for all RX/TX modes
> F4 and F5 configured for CW and Data RX
>
> Configuration:
> TX Test (no RF out)
> Audio fed into line in (but no difference with mic input)
> Line in set for "4 bars" ALC (but doesn't seem to make any difference how
> many bars)
> Data Mode selected
> Monitor turned up to comfortable level.
>
> If F5 is selected as the RX filter, all is well. But if either of the
> other filters is selected for RX and tones are transmitted, the tones have
> an audible "tick" with a frequency of (I'm guessing) around 40 Hz on top
> of the tone. The frequency of the tick changes slightly as the frequency
> of the tone changes. Audio input levels don't change the tick until the
> audio level approaches 0, then the ticks go away. Modifying shift or
> bandwidth doesn't affect the tick. Audio input signal is clean. Change
> the RX filter back to F5 and all is well again. Switch to USB and all is
> well with any filter.
>
> My guess is there is something funny (a bug?) with the selection of the
> Data TX filter.
>
> Anyone else have this problem? Any ideas?
>
> Thanks
>
> Joe N6KK
>
>
> ______________________________________________________________
> 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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Joe Barger

Re: K3 Data Mode Transmit Issue

After going back through the archives (which I should have done first),
Iain, N6ML made a recording of the "ticks" I have heard (
http://www.mail-archive.com/elecraft@.../msg68942.html ), so my
observations just add to what the others that have already been reported.
In my case, turning TEXT DEC on or off made no difference and trying REV
DATA made no difference.

Joe N6KK

----- Original Message -----
From: "Joe Barger" <[hidden email]>
To: <[hidden email]>
Sent: Friday, March 13, 2009 10:08 AM
Subject: Re: [Elecraft] K3 Data Mode Transmit Issue

>I had a chance to do a little more investigating today.
>
> In summary, in data mode "AFSK A" and AFSK TX: OFF, F5 had no ticks (F2
> and
> F4 had ticks). With AFSK TX: ON, no filter had ticks.
>
> With the data mode in "DATA A", AFSK TX made no difference if it was on or
> off. F4 and F5 had no ticks, but F2 had the ticks.
>
> I'm not sure AFSK TX has fixed the root cause of the problem it was
> designed
> for. If the noise that the AFSK TX filter was designed to remove is
> actually caused by "RFI, ground loops, low AF level, ... ", why are there
> combinations of main filters on receive that don't display the ticks
> whether
> the AFSK TX filter is on or off? F5 never had the ticks on transmit. I
> believe that a single TX filter (F2 in my case) is used for transmit, so
> why
> do the various choices of RX filters affect the transmit "ticks"? Of
> course, the "ticks" I'm hearing may not be related to the other reported
> noise sources at all, but there still seems to be a problem.
>
> Can anyone else reproduce these results? Any thoughts Lyle?
>
> Joe N6KK
>
>
>
> ----- Original Message -----
> From: "Joe Barger" <[hidden email]>
> To: <[hidden email]>
> Sent: Wednesday, March 11, 2009 5:45 PM
> Subject: [Elecraft] K3 Data Mode Transmit Issue
>
>
>> The setup:
>>
>> K3 with latest firmware.
>>
>> Main Filters installed:
>> F2 2.7 KHz
>> F4 500 Hz
>> F5 200 Hz
>>
>> F2 configured for all RX/TX modes
>> F4 and F5 configured for CW and Data RX
>>
>> Configuration:
>> TX Test (no RF out)
>> Audio fed into line in (but no difference with mic input)
>> Line in set for "4 bars" ALC (but doesn't seem to make any difference how
>> many bars)
>> Data Mode selected
>> Monitor turned up to comfortable level.
>>
>> If F5 is selected as the RX filter, all is well. But if either of the
>> other filters is selected for RX and tones are transmitted, the tones
>> have
>> an audible "tick" with a frequency of (I'm guessing) around 40 Hz on top
>> of the tone. The frequency of the tick changes slightly as the frequency
>> of the tone changes. Audio input levels don't change the tick until the
>> audio level approaches 0, then the ticks go away. Modifying shift or
>> bandwidth doesn't affect the tick. Audio input signal is clean. Change
>> the RX filter back to F5 and all is well again. Switch to USB and all is
>> well with any filter.
>>
>> My guess is there is something funny (a bug?) with the selection of the
>> Data TX filter.
>>
>> Anyone else have this problem? Any ideas?
>>
>> Thanks
>>
>> Joe N6KK
>>
>>
>> ______________________________________________________________
>> 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
>>
>
>
> ______________________________________________________________
> 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
>

KK7P

Re: K3 Data Mode Transmit Issue

In reply to this post by Joe Barger

> Can anyone else reproduce these results? Any thoughts Lyle?

We have field test code that seems to fix this. I say "seems to"
because everyone who has observed this and then tried the new code has
further observed that the problem went away.

73,

Lyle KK7P

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Joe Barger

Re: K3 Data Mode Transmit Issue

Thanks Lyle. I'll wait patiently for the new code.

73

Joe N6KK

----- Original Message -----
From: "Lyle Johnson" <[hidden email]>
To: <[hidden email]>
Sent: Friday, March 13, 2009 12:03 PM
Subject: Re: [Elecraft] K3 Data Mode Transmit Issue

>> Can anyone else reproduce these results? Any thoughts Lyle?
>
> We have field test code that seems to fix this. I say "seems to"
> because everyone who has observed this and then tried the new code has
> further observed that the problem went away.
>
> 73,
>
> Lyle KK7P
>
>
>
> ______________________________________________________________
> 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
>