K3 - FT8 - low power issues when TX audio below 900hz

[LA8AW]

Hi,

On all HF bands I have very low power output when I TX with a audio
frequency below  900hz. Between 900 - 2300hz all is normal.  On 50Mhz,
power the output start dropping when I come below 500Hz. (FL1 2.7 selected
on all bands)

Using Microham MicroKeyer II; Audio switching is set to Digital settings,
using line in (rear). Tested with 2 different MicroKeyer II same result.

FT8 is soundcard configured Input: Line (microham CODEC), Output: Headset
Earphone (microHAM CODEC).

This was causing problems for me when I tried to work stations running DX
Mode (KH1).

K3 with the "new" synth card, all mods done.
Filters installed: 2.7, 1.8, 1.0, 0.4, 0.25
DATA enabled for all filters

Any hints on where to look next?


73 de LA8AW - Odd-Egil
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[Bob McGraw - K4TAX]

Is the WSJT-X application setting in the F2 menu under Radio set for
MODE = Data/Pkt and that the Split Operation set to RIG? This keeps the
transmit tones correct within the passband of the SSB filter.  Here in
this application SPLIT is not the same principle as split when working
DX.  SPLIT using the RIG setting will adjust the VFO frequency such that
the transmitted tone is always between 1500 and 2000 Hz.

/"Split Operation/: Significant advantages result from using*Split*mode
(separate VFOs for Rx and Tx) if your radio supports it. If it does
not,/WSJT-X/can emulate such behavior. Either method will result in a
cleaner transmitted signal, by keeping the Tx audio always in the range
1500 to 2000 Hz so that audio harmonics cannot pass through the Tx
sideband filter. Select*Rig*to use the radio’s Split mode, or*Fake It*to
have/WSJT-X/adjust the VFO frequency as needed, when T/R switching
occurs. Choose*None*if you do not wish to use split operation"


73
Bob, K4TAX




On 7/18/2018 2:11 PM, LA8AW wrote:

> Hi,
>
> On all HF bands I have very low power output when I TX with a audio
> frequency below  900hz. Between 900 - 2300hz all is normal.  On 50Mhz,
> power the output start dropping when I come below 500Hz. (FL1 2.7 selected
> on all bands)
>
> Using Microham MicroKeyer II; Audio switching is set to Digital settings,
> using line in (rear). Tested with 2 different MicroKeyer II same result.
>
> FT8 is soundcard configured Input: Line (microham CODEC), Output: Headset
> Earphone (microHAM CODEC).
>
> This was causing problems for me when I tried to work stations running DX
> Mode (KH1).
>
> K3 with the "new" synth card, all mods done.
> Filters installed: 2.7, 1.8, 1.0, 0.4, 0.25
> DATA enabled for all filters
>
> Any hints on where to look next?
>
>
> 73 de LA8AW - Odd-Egil
> ______________________________________________________________
> 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
> Message delivered to [hidden email]
>

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[jh3sif]

If your WSJT-X is enabled to CAT control your K3, WSJT-X change VFO frequency on transmit so that FT8 AF frequency into K3 is center of TX filter.

However, before WSJT-X has this feature, I did not have any issue on transmitting < 900Hz AF.
Are you using DATA-A mode on K3 for digi-mode? If you use SSB mode on K3 for digi-mode and TX EQ has been set to reduce <900Hz audio level, this could be the cause.

73 de JH3SIF, Keith

> 2018/07/19 4:11、LA8AW <[hidden email]>のメール:
>
> Hi,
>
> On all HF bands I have very low power output when I TX with a audio
> frequency below  900hz. Between 900 - 2300hz all is normal.  On 50Mhz,
> power the output start dropping when I come below 500Hz. (FL1 2.7 selected
> on all bands)
>
> Using Microham MicroKeyer II; Audio switching is set to Digital settings,
> using line in (rear). Tested with 2 different MicroKeyer II same result.
>
> FT8 is soundcard configured Input: Line (microham CODEC), Output: Headset
> Earphone (microHAM CODEC).
>
> This was causing problems for me when I tried to work stations running DX
> Mode (KH1).
>
> K3 with the "new" synth card, all mods done.
> Filters installed: 2.7, 1.8, 1.0, 0.4, 0.25
> DATA enabled for all filters
>
> Any hints on where to look next?
>
>
> 73 de LA8AW - Odd-Egil
> ______________________________________________________________
> 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
> Message delivered to [hidden email]

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Please help support this email list: http://www.qsl.net/donate.html
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