Hi Ed,
We had exactly the same problem with all six of our MARS modified K3 transceivers at NSS. We were forced to replace our MARS modified K3 transceiver transmitting on 9448 kHz with an old FT-1000MP... Only on other bands where our assigned MARS frequency was very close to the edge of the ham band did the K3 produce near normal RF output power but only if VFO A was set to listen just inside the edge of the ham band nearest to our MARS\ transmitting frequency on VFO B. This is the behavior we discovered with all of our K3 transceivers: - Transmitting on 9448 kHz or any other MARS frequency on either VFO A or VFO B works perfectly but only when not operating split . - Operating split with both VFO A and VFO B set for any frequencies within the same ham band works perfectly. However -- when selecting split operation -- VFO B RF output power steadily drops as VFO A is tuned to receive at an increasingly large frequency split relative to VFO B transmitting on a fixed MARS freq. It appears that when operating split and transmitting on VFO B on a MARS frequency, the K3 bandpass filter associated with the VFO A receiving VFO is always selected for use with the VFO B split transmitter outside the ham band. When VFO B is tuned to transmit outside the ham band (e.g. 9448 KHz and VFO A listening on 10113) the VFO B transmitted signal on 9448 kHz cannot pass through the standard 30 meter bandpass filter automatically selected by the K3 for use with VFO A. Proposed solution: the K3 must dynamically select the proper KBPF3 bandpass filter before transmitting on a VFO B split frequency outside the ham bands. Then the K3 must dynamically switch back the stock K3 band pass filter each time the K3 switches from VFO B transmit to VFO A receive inside the ham band.. This exact same problem occurs on every band, not just 30 meters. For example on 80 meters NSS was transmitting with VFO B on 4038 kHz. We were forced listen with VFO A set just below 4000 kHz. As a result we were forced to ask CW stations to call us just below 4000 kHz, an unusual operating practice. If we tuned VFO A to receive on 3530 kHz the VFO B transmitter power output on 4038 kHz was dramatically lowered. N3CW experienced exactly the same problem when transmitting with inside the 30 meter ham band and listening on 9448 kHz. Hopefully the capability to dynamically select to proper bandpass filter before each transmission can be added to the K3 before the next Armed Forces Day Cross-Band Test in twelve months... 73 Frank W3LPL ----- Original Message ----- From: "Ed G" <ed.n...@gmail.com> To: "Mark E. Musick" <markmus...@sbcglobal.net>, elecraft@mailman.qth.net Sent: Saturday, May 12, 2018 8:45:02 PM Subject: Re: [Elecraft] K3 Strange Power Output Problem Hi Mark! I am transmitting on 10.113, and I do not change this. I am in Split mode, listening for NSS (who is transmitting on 9.448). I am only seeing about 20 watts out, even though the K3 Power setting says 100 watts. If I change my RECEIVE frequency – not my transmit frequency – once I get above 9.850 on RECEIVE, my power out returns to the expected 100 watts. --Ed— Sent from Mail for Windows 10 From: Mark E. Musick Sent: Saturday, May 12, 2018 4:36 PM To: 'Ed G'; elecraft@mailman.qth.net Subject: RE: [Elecraft] K3 Strange Power Output Problem Hi Ed, You don't have a transmit problem at all. It is not an anomaly. The amateur band starts at 10.100 MHz. You shouldn't be transmitting below that frequency. I'm surprised the K3 allowed you to do that. The K3/K3S gives an out of band error and won't transmit beyond some amount below and above the amateur band limits, I believe allowing for MARS frequencies. The reason for the relay click and your lower output is due to switching of the bandpass filters in the K3. They are not designed to transmit down there. This is also why you are seeing a reduction in receive sensitivity. You need the BPF3A to receive outside the ham bands. Again, because you are limited by the bandpass filters for the ham bands in the K3. If you have more questions, let us know here on the reflector and we will try to answer them for you. 73, Mark, WB9CIF -----Original Message----- From: elecraft-boun...@mailman.qth.net <elecraft-boun...@mailman.qth.net> On Behalf Of Ed G Sent: Saturday, May 12, 2018 7:25 PM To: elecraft@mailman.qth.net Subject: [Elecraft] K3 Strange Power Output Problem Hello, I noticed this power output anomaly today while trying to work the NSS station. My K3 was in split mode, transmitting on 10.113.5. While I was listening on 9.448 (the NSS transmit frequency), I noticed that even though my K3 power level was set at 100 watts, the K3 was only putting out about 20 watts. Two different power meters (the K3 internal meter and an outboard LP-100A) gave me the 20 watt reading. When I listened on my transmit frequency of 10.113.5, I was getting the full 100 watts out. A quick investigation showed that as I tuned my listening frequency down, I got the full 100 watts out until I got to about 9.850 mHz. When I listened below that, K3 transmit power on 10.113.5 dropped immediately down to 20 watts. Not sure why I am seeing this? One additional note – I hear a relay click inside the K3 when I tune my receive frequency below 9.850. I see the anomaly with the subreceiver either on or off. --Ed— Sent from Mail for Windows 10 --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to markmus...@sbcglobal.net ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to donov...@starpower.net ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
