Date   
Re: Transmit ALC loop and detector design

Charles Garner
 

Hmmm OK so it's not proprietary but it will cost me $25 to read about. Not being deliberately trite here but is there another open source that describes the implementation in some detail?  I had a feeling this was going to be a tough search .

Re: Transmit ALC loop and detector design

Bob Hallock
 

Check  Fredy Cady's K3s book page 170.

On Tue, Sep 25, 2018 at 4:40 PM, Charles Garner <skyviewcharles@...> wrote:
I may be treading on proprietary ground here but I'd sure be interested if anyone at Elecraft or elsewhere could shed some detailed light on how the transmit ALC loop is implemented, especially how and where the loop detection is done. I recall hearing that the detection is sensitive to excessive 3rd order IMD which is good attribute but can anybody describe the implementation?  I've also heard it is implemented "in the DSP" which is probably diplomatic words meaning "it's proprietary".  Hope I'm mistaken. 
Thanks. N6AF Chuck 


Re: Trasnverter output power issue

Ian White
 

Many transverter users  see the same problem, because the transverter output is very often being used to drive expensive and fragile LDMOS PA devices.

 

One power surge from the transceiver can kill an LDMOS device in microseconds, due to gate voltage breakdown. A replacement device can cost several hundred dollars, and the repair often involves heating the entire PA module on a large hotplate, with a high risk of damaging other components.

 

(Please don't tell us that "Other transceivers may be far worse." We all know that. But here in this forum, the subject is the K3/S.)

 

Ten years ago when the K3 firmware was first developed, a transverter driving and LDMOS PA was not an important user scenario. But times change. It now requires some very serious attention - not only from users, but also I think from Elecraft.

 

There are at least three possible causes (none of which excludes any of the others happening at the same time).

 

1. User error: under-driving with audio, which causes the K3 to ramp up the internal TX gain. Then the next return to correct drive levels can cause an overshoot. The K3 will quickly reduce the TX gain back to normal - but for an LDMOS PA, this may already be too late.

 

So, NEVER reduce RF output power by reducing the audio drive. Follow the drill: for data modes, aim for four solid bars on the "ALC" meter with the 5th bar flickering. For SSB, always use compression to prevent overdriving on voice peaks.

 

2. Possible user error: setting the K3's PWR control too far below the maximum. This may create additional 'headroom' for a power surge at the transverter output. I try to leave the PWR setting very close to maximum (no lower than about -1.0dB) and then set the correct drive level *inside the transverter*.

 

3. Firmware: because even one power surge can have such devastating and expensive consequences, transverter users need a *strong* assurance that the K3 can never be fooled into delivering a power surge. Maybe a post-calibration option to "Lock all internal TX gain settings for transverter outputs. Do not allow modification on-the-fly. Only unlock for the next calibration."

 

Comments, please?

 

 

73 from Ian GM3SEK

 

 

 

From: Elecraft-K3@groups.io [mailto:Elecraft-K3@groups.io] On Behalf Of Anto via Groups.Io
Sent: 26 September 2018 08:04
To: Elecraft-K3@groups.io
Subject: Re: [Elecraft-K3] Trasnverter output power issue

 

Hi Olli
I did firmware update ( it had 5.16 ) then re-calibration.
Now it seems fixed, I will test on EME next days.

Thanks for suggestion

73 Anro IK4PMB

Re: Trasnverter output power issue

ik4pmb
 

Hi Olli
I did firmware update ( it had 5.16 ) then re-calibration.
Now it seems fixed, I will test on EME next days.

Thanks for suggestion

73 Anro IK4PMB

Transmit ALC loop and detector design

Charles Garner
 

I may be treading on proprietary ground here but I'd sure be interested if anyone at Elecraft or elsewhere could shed some detailed light on how the transmit ALC loop is implemented, especially how and where the loop detection is done. I recall hearing that the detection is sensitive to excessive 3rd order IMD which is good attribute but can anybody describe the implementation?  I've also heard it is implemented "in the DSP" which is probably diplomatic words meaning "it's proprietary".  Hope I'm mistaken. 
Thanks. N6AF Chuck 

Re: K3S & KX3 Polling Frequency for Arduino

Max NG7M
 

As a follow up to Rich VE3KI and Dave AA6YQ, I recently posted/created a YouTube Video that goes into a high level of detail on using Win4K3Suite to share a K3 CAT feed across multiple applications and hardware: https://www.youtube.com/watch?v=zbf7BPfcj4U

Here is a direct link to the diagram I reference in the video.

These concepts are applicable to other sharing techniques and as Dave mentioned for read only apps or hardware, you could do that without Win4K3Suite.  Win4K3Suite does the best and most reliable job of creating virtual K3 CAT feed instances.  Hardware and software won't know that they are not connected directly to the K3/S.

Max NG7M

Re: K3S & KX3 Polling Frequency for Arduino

Dave AA6YQ
 

+ AA6YQ comments below

"I'm not aware of any software package that allows a comm port to be shared by two different apps."

Here are two - they both work by connecting directly to the real K3, creating a virtual K3 in software, and then connecting to other apps using multiple virtual com ports, one per app, that all control the same virtual K3 and through it the real K3:

LP-Bridge (<http://www.telepostinc.com/LPB.html>)

Win4K3Suite (<https://va2fsq.com/>)

As for the two radio control connectors on the back of the K3S, my understanding is that when the USB port is active for radio control, the RS232 port simply echoes the serial communications on the USB port. I don't believe it is intended to be used as a second independent control port.

+ Commander, the transceiver control component of the DXLab Suite, has long provided a limited form of this by using the same emulation technique. With its "Primary CAT Port" connected to your K3, Comamnder provides a "Secondary CAT Port" that can be connected to another application (or device) that wishes to track or control the transceiver's frequency or mode. This is often used to enable panadaptors and skimmers to track and control the transceiver's frequency in parallel with Commander.

+ Commander's capability is unique in that its "Secondary CAT Port" is not constrained to use the same CAT protocol as the transceiver; it supports mostof the CAT protocols now in common use. Thus with Commander's "Primary CAT port" connected to a K3, it's "Secondary CAT port" could be connected to an HF amplifier like the Icom PW-1, which uses the Icom CAT protocol (CIV) to track the transceiver's frequency.

73,

Dave, AA6YQ

Re: K3S & KX3 Polling Frequency for Arduino

ve3ki
 

"I'm not aware of any software package that allows a comm port to be shared by two different apps."

Here are two - they both work by connecting directly to the real K3, creating a virtual K3 in software, and then connecting to other apps using multiple virtual com ports, one per app, that all control the same virtual K3 and through it the real K3:

LP-Bridge (<http://www.telepostinc.com/LPB.html>)

Win4K3Suite (<https://va2fsq.com/>)

As for the two radio control connectors on the back of the K3S, my understanding is that when the USB port is active for radio control, the RS232 port simply echoes the serial communications on the USB port. I don't believe it is intended to be used as a second independent control port.

73,
Rich VE3KI


On Mon, Sep 24, 2018 at 04:26 PM, Michael Foerster wrote:
Rich,

I hadn't thought about how the remote control software (RemoteHams.com) would react to the Metacommand change (AI2 mode).  
   This brings up the question, if the rig is put into "AI2" mode, does this affect BOTH comm ports on the K3S or just the one where the command is executed?  I'll have to try to figure out a way to test this. What comes to mind is to try to connect the Serial and the USB ports to different instances of the K3 comm firmware, or at least to another terminal session of some type and see if they both react to the twist of the knob. 

Larry,
  I could monitor the comms to see if something gets transmitted, but I do need to have the ability to write the new power setting to the radio.  I'm not aware of any software package that allows a comm port to be shared by two different apps.
  Also, it is only occasionally that I actually use the radio remotely so it will not be running all of the time.

What I have in mind is to emulate the KPA500 command structure using the Arduino so that I can use the LDMOS amplifier remotely through a second comm port.  I do have a KPA500, but a part of my design goal on this is to allow the LDMOS amp to be used remotely as well.  

Thanks for the replies...

73,

Mike, W0IH

Re: K3S & KX3 Polling Frequency for Arduino

Michael Foerster
 

Rich,

I hadn't thought about how the remote control software (RemoteHams.com) would react to the Metacommand change (AI2 mode).  
   This brings up the question, if the rig is put into "AI2" mode, does this affect BOTH comm ports on the K3S or just the one where the command is executed?  I'll have to try to figure out a way to test this. What comes to mind is to try to connect the Serial and the USB ports to different instances of the K3 comm firmware, or at least to another terminal session of some type and see if they both react to the twist of the knob. 

Larry,
  I could monitor the comms to see if something gets transmitted, but I do need to have the ability to write the new power setting to the radio.  I'm not aware of any software package that allows a comm port to be shared by two different apps.
  Also, it is only occasionally that I actually use the radio remotely so it will not be running all of the time.

What I have in mind is to emulate the KPA500 command structure using the Arduino so that I can use the LDMOS amplifier remotely through a second comm port.  I do have a KPA500, but a part of my design goal on this is to allow the LDMOS amp to be used remotely as well.  

Thanks for the replies...

73,

Mike, W0IH

Re: Trasnverter output power issue

Olli
 

Did you do the power re-calibration routine again to see id it fixes it?

73, Olli



Am 24.09.2018 um 07:58 schrieb Anto via Groups.Io <anto_next@...>:

Hi all
I've been using my K3 since long time for transverter driving.
Since some month I have a strange issue, the output power ( I use from -10 to -7 dBm to drive transverter ) is not constant, after some seconds from start transmission, it lowers.
I have also another bigger problem, if I move the power control knob during transmission power goes to maximum for a moment then returns to normal, this costed to me to burn ldmos on my SSPA due to high driving power.
Any clue before I start to investigate ?

Trasnverter output power issue

ik4pmb
 

Hi all
I've been using my K3 since long time for transverter driving.
Since some month I have a strange issue, the output power ( I use from -10 to -7 dBm to drive transverter ) is not constant, after some seconds from start transmission, it lowers.
I have also another bigger problem, if I move the power control knob during transmission power goes to maximum for a moment then returns to normal, this costed to me to burn ldmos on my SSPA due to high driving power.
Any clue before I start to investigate ?

Re: High swr on two bands

Barney Scholl
 

I have a K3 with KAT3 tuner. With the tuner active it will tune it. In bypass it still shows a high swr on those bands. I believe that when in tx Gail calibrate it bypasses the tuner and will not complete because of high swr. 

Re: High swr on two bands

Joe Subich, W4TV
 

You do not say whether you have a K3 or K3S and a KAT3 or KAT3A
installed. With the K3/KAT3, "bypass" simply set the KAT3 to
the memorized 50 Ohm setting.

Try turning on the KAT3 and "Tuning" the dummy load at the
bottom, top and middle of both 18 and 21 MHz bands.

73,

... Joe, W4TV

On 2018-09-22 11:06 PM, Barney Scholl wrote:
I was attempting to perform a Tx gain calibration and it failed due
to a high swr. I checked the swr outside of the tx gain utility and
in fact the swr into a 50 ohm load and it was about 4 to one 18 and
21 mhz. It dropped back down to 1 to 1 on all bands other than 18 and
21 mhz. I tried two 50 ohm loads and the same readings. Any ideas? I
have been able to run the Tx gain calibration before. Barney K3LA

High swr on two bands

Barney Scholl
 

I was attempting to perform a Tx gain calibration and it failed due to a high swr. I checked the swr outside of the tx gain utility and in fact the swr into a 50 ohm load and it was about 4 to one 18 and 21 mhz. It dropped back down to 1 to 1 on all bands other than 18 and 21 mhz. I tried two 50 ohm loads and the same readings. Any ideas? I have been able to run the Tx gain calibration before. Barney K3LA

Re: K3S & KX3 Polling Frequency for Arduino

Larry K8UT <k8ut@...>
 

Hi Mike

You might find that your favorite logging program already queries the radio for that data, and all you need to do is lurk on the CAT traffic to get the data your need. I wrote a CAT router for my K3S that runs on a Raspberry Pi and optimizes rig traffic by caching the queries from logging programs, panadapters, skimmers, etc. To get it working I had to inventory which CAT queries were generated by which applications. The resultant spreadsheet covers DXLab, HRD, NaP3, CW Skimmer and N1MM+. It might be useful to you - I've sent you copy via direct email.

An alternative suggestion: The project you described will query the radio for current band & power levels, then adjust the radio for the desired amp-driving power for each band. When you turn off the amp (or go to amplifier standby) the arduino will return the radio to the desired no-amp power levels. Would it be easier to have your arduino behave like an attached Elecraft amplifier and put the radio in "attached amplifier mode?" With amp-connected, you now take advantage of the K3S's ability to store two power settings (amp, no-amp) for each band. (I do not know of the KX3 has a similar feature)

-larry (K8UT)

------ Original Message ------
From: "Michael Foerster" <mfroster@...>
Sent: 2018-09-22 17:00:33
Subject: [Elecraft-K3] K3S & KX3 Polling Frequency for Arduino

I’m working on an Arduino circuit to go between a home brew (from kit) LDMOS amplifier (~1200w) and either my K3S or KX3. The Arduino will watch for band changes on the rig (via RS232 Comms) to change the band switch on the Amp.  It will also set the power level on the rig to keep from overdriving the Amp input.  I’m hoping to set up the Comms to work with both rigs.

I know that I can use the MetaCommand “AI2” which will report both the Frequency change and Power Control setting.  However I’m concerned about the AI command somehow being reset and not reporting correctly so I’m thinking about using the “FA” and “PC” commands to poll the radio every few seconds.

So my question is, can I poll either rig every second or two to check for frequency change and somewhat less often for user power change?  The frequency check should be somewhat often so that when you do change bands, that the Ampband change is reasonably fast.  Anyone have any idea how often you can poll the radios and what the ramifications are for too much comm traffic?

Another question: can the RS232 and USB Comms on the K3S be used independently?  I also have my K3S connected for Remote operation, so I would need one port for the Amp polling and the other for Remote control.

Thanks, 

Mike, W0IH

Re: K3S & KX3 Polling Frequency for Arduino

ve3ki
 

Are you using logging software that also polls the radio? If so, changing the mode to AI2 may not be tolerated by the logging software, which may not react favourably to unexpected responses from the radio. If you can rely on logging software to poll the radio periodically, maybe you can just eavesdrop on the polls and responses and use that information. Perhaps the RS232 port can be used in such a "listen-only" mode while the USB port is being used for radio control.

73,
Rich VE3KI


On Sat, Sep 22, 2018 at 05:00 PM, Michael Foerster wrote:
I’m working on an Arduino circuit to go between a home brew (from kit) LDMOS amplifier (~1200w) and either my K3S or KX3. The Arduino will watch for band changes on the rig (via RS232 Comms) to change the band switch on the Amp.  It will also set the power level on the rig to keep from overdriving the Amp input.  I’m hoping to set up the Comms to work with both rigs.

I know that I can use the MetaCommand “AI2” which will report both the Frequency change and Power Control setting.  However I’m concerned about the AI command somehow being reset and not reporting correctly so I’m thinking about using the “FA” and “PC” commands to poll the radio every few seconds.

So my question is, can I poll either rig every second or two to check for frequency change and somewhat less often for user power change?  The frequency check should be somewhat often so that when you do change bands, that the Ampband change is reasonably fast.  Anyone have any idea how often you can poll the radios and what the ramifications are for too much comm traffic?

Another question: can the RS232 and USB Comms on the K3S be used independently?  I also have my K3S connected for Remote operation, so I would need one port for the Amp polling and the other for Remote control.

Thanks, 

Mike, W0IH

Re: K3S & KX3 Polling Frequency for Arduino

Al N1AL
 

Why not just periodically send an AI2 command to make sure the K3 is always in that mode?

On 09/22/2018 02:00 PM, Michael Foerster wrote:
...
I know that I can use the MetaCommand “AI2” which will report both the Frequency change and Power Control setting.  However I’m concerned about the AI command somehow being reset and not reporting correctly so I’m thinking about using the “FA” and “PC” commands to poll the radio every few seconds.
...

K3S & KX3 Polling Frequency for Arduino

Michael Foerster
 

I’m working on an Arduino circuit to go between a home brew (from kit) LDMOS amplifier (~1200w) and either my K3S or KX3. The Arduino will watch for band changes on the rig (via RS232 Comms) to change the band switch on the Amp.  It will also set the power level on the rig to keep from overdriving the Amp input.  I’m hoping to set up the Comms to work with both rigs.

I know that I can use the MetaCommand “AI2” which will report both the Frequency change and Power Control setting.  However I’m concerned about the AI command somehow being reset and not reporting correctly so I’m thinking about using the “FA” and “PC” commands to poll the radio every few seconds.

So my question is, can I poll either rig every second or two to check for frequency change and somewhat less often for user power change?  The frequency check should be somewhat often so that when you do change bands, that the Ampband change is reasonably fast.  Anyone have any idea how often you can poll the radios and what the ramifications are for too much comm traffic?

Another question: can the RS232 and USB Comms on the K3S be used independently?  I also have my K3S connected for Remote operation, so I would need one port for the Amp polling and the other for Remote control.

Thanks, 

Mike, W0IH

Re: KIO3 Main Board Board Wanted

Ed Pflueger
 

By the way John we worked RTTY on 9/28/2008 @ 01:18 7.063 mhz.

Ed..

-----Original Message-----
From: Elecraft-K3@groups.io [mailto:Elecraft-K3@groups.io] On Behalf Of Ed Pflueger
Sent: Friday, September 14, 2018 3:51 PM
To: Elecraft-K3@groups.io
Subject: Re: [Elecraft-K3] KIO3 Main Board Board Wanted

Mine says it's a REV A but in 2016 had the Output Buffer Gain Mod R8 13K done at the factory.

Ed.. AB4IQ

-----Original Message-----
From: Elecraft-K3@groups.io [mailto:Elecraft-K3@groups.io] On Behalf Of John Spigel
Sent: Friday, September 14, 2018 9:26 AM
To: Elecraft-K3@groups.io
Subject: Re: [Elecraft-K3] KIO3 Main Board Board Wanted

My K3 took a nearby lightning hit resulting in loss of communications and an intermittent TX via RTS. I narrowed this down to the main KIO3 RevC board and probable faulty U1. Anybody have an uneeded board from their upgrade for me to try before I ship the radio?

Thanks!

John W1AN

Re: K3 digital problems, again

Peter Kohl <pkohl1960@...>
 

Hi Larry,

I know from my Windows-time (I am now a die-hard Linuxer) that Win changes the numbers of the USB-devices from time to time... check this out.

73 de Peter ON4EZJ

On 15/09/18 23:19, Larry wrote:
As you may remember when i received my K3 back from Elecraft repair a
couple weeks ago i quickly installed the USb cable and set the radio up
for Digital operation.  The only way it would work with LOG4OM and WSJT
was using the OMNIrig setting in Log4OM and leaving the rig selection in
the "Settings" screen on WSJT set to none.  Worked great, for about 50
QSO's!  Then it quit,  I've been playing with options, cables etc now
for two weeks in my spare time trying to make it work again. Still
nothing.  I know information is going from the radio to the computer as
i see the data on the screen.  However going back the other way to the
transmitter, well i don't know.  The radio doesn't key whether i have
the program options set for Cat, USB, Vox or whatever else i can think
of.  So now is the computer at fault or is there something that all of a
sudden changed in the radio?  Radio works fine on CW and SSB, just won't
transmit in FT8 mode.  Am i the only one with this problem?

In case anyone cares, i'm beginning to feel like my scalp has been
taken!  Less hair on top!

Larry

W0OGH

Life could be a lot simpler.