KPA1500 FT8 Split Operation ATU Issue


Bill - AK6A
 

   I am having an issue with my KPA1500 when operating FT8 SPLIT (WSJT-X Split Operation to SPLIT or FAKE IT) and using CI-V control. When WSJT-X starts or ends its transmit cycle the KPA1500 ATU IN front panel LED blinks. When this happens the KPA1500 will also randomly go into an actual tune cycle which is not cleared until the next FT8 transmit cycle.

If I set WSJT-X Split Operation to NONE the problem does not occur. If I set the WSJT-X Split Operation to SPLIT or FAKE IT and disconnect the CI-V control cable to the KPA1500 then the ATU Control acts normally. 
 
This problem occurs in both Operate and Stand By, using either an antenna or dummy load, using either local or remote control.

If I set the FT8 "frequency" to the center (1500 KHz) in SPLIT the issue does not occur, the problem only shows up when I venture away from the center and the VFO actually shifts frequency when I go from receive to transmit.
 
I can duplicate this issue using either an Icom IC-7300 with direct CI-V connection or a Yaesu FTDX101MP using a MicroKeyer II CI-V interface.

This appears to be some sort of an issue when the VFO shifts frequency between transmit and receive when using CI-V control. I've tried different radios and different FT8 software with the same issues. I'm not sure if my KPA1500 has a problem or how to possibly correct this.

Is anyone else seeing this issue? If you run FT8 and don't look at the LED you might not notice it blinking. The problem becomes very apparent when I use the KPA1500 remote APP and that shows the KPA1500 randomly going into a tune cycle at the end of the FT8 transmission and it doesn't clear until the start of the next cycle. The problem will only occur in SLPIT when the FT8 frequency is offset away from the center (ex: 500 Hz or 2500Hz) and using CI-V control.
 
 I would appreciate your help in correcting this issue. Does the KPA1500 have some sort of error/log file that can show what it thinks is happening?

Thanks!

Bill - AK6A


Jim Denneny
 

Hi Bill

My config is K3S with KPA1500.  I leave SPLIT in NONE.  I sometimes select HOUND in ADVANCED tab during F/H qso's.  I have never had an instance to need to move SPLIT to RIG or FAKE-IT.  As you noted, no issues in NONE.  Curious - what scenario would you need SPLIT?

Jim K7EG


Bill - AK6A
 

Hi Jim,

 

    Thanks for your response. There are several reasons to use the WSJT-X Split Modes instead of None. In None WSJT-X shifts your transmit audio frequency rather than your actual transmit center frequency. In None you are limited to the width of the transmit passband of your radio. Depending on your radio your audio might start to fall off above 2500 Hz or below 500 Hz. If you want to select a spot on the waterfall to transmit in these areas you are out of luck. In Split or Rig modes WSJT-X shifts your actual transmit frequency and your transmit audio always stays in the middle of your radios passband. This lends itself to cleaner audio and the ability to go anywhere on the waterfall. In Rig mode WSJT-X shifts VFO A, in Split it uses VFO A for RX and VFO B for TX.

     The second reason to use a Split mode is with the FT8 software I use (JTDX) to use F/H mode the radio has to be configured in either Split or Rig. If I stayed in None then I’d always have to go to the radio setup page and go to Split when I wanted to run F/H.

   Anyway, this is how I understand how it all works. 

 

73,

 

Bill - AK6A


Jim Denneny
 

Thanks for your clarification.  I do not use split in F/H either as I generally find the FOX in the low end of the passband around 300Hz and I TX above 1000  Hz.  I agree if FOX is outside the passband, SPLIT would be required.  So far, I have found the FOX inside passband.

73, Jim K7EG


Rick NK7I
 

“Fake it” or split is suggested to keep the TX audio within the 1500-2000 Hz range. 

To have that audio go below that range, risks transmitting harmonics which add garbage and interference to other receivers. 

It’s most apparent in F/H mode when the app selects the tones, not the user, in a reply, always low. 

Just allow the app to control the VFO(s), using other than “None” and you won’t cause issues.   It’s just that simple. 

73,
Rick NK7I

Email spiel Czech corruptions happen

On Sep 24, 2021, at 7:00 AM, Jim Denneny <57JNDenneny@...> wrote:

Thanks for your clarification.  I do not use split in F/H either as I generally find the FOX in the low end of the passband around 300Hz and I TX above 1000  Hz.  I agree if FOX is outside the passband, SPLIT would be required.  So far, I have found the FOX inside passband.

73, Jim K7EG


John Canfield
 

I run FT8 in split mode with a K3s and KPA1500 - solid performance and zero issues.

John, WB5THT


Bill Maddock
 






On Tuesday, September 28, 2021, 7:57 AM, John Canfield <johnwcanfield@...> wrote:

I run FT8 in split mode with a K3s and KPA1500 - solid performance and zero issues.

John, WB5THT