Hi Bob,
Thanks, I'll try your ideas. We have a year to get ready for our next NSS operation... NSS was a Field Day style operation with AB-577 towers, all of the NSS towers and buildings were demolished 20 years ago except for three 600 foot towers that are all in the red zone of a firing range! Because its a Field Day style operation, we don't have enough time to install separate receiving antennas despite our 500+ acre NSS site... Our objective is to transmit on our assigned MARS frequencies outside the ham bands (e.g., 9448 kHz) and listen inside the adjacent ham band (e.g., 10128 kHz). We don't need to listen to both frequencies at the same time. Our K3 main receiver and KRX3 subreceiver share the same antenna and the transceivers have KBPF3 bandpass filters installed in the main receiver only . Before we began NSS operations on Saturday morning we had no idea that the K3 could not perform out of ham band split operations without using the KRX3 sub receiver. When we realized that our transmit power output was severely reduced by using wide split (e.g., 9448 / 10128 kHz) we started to search for a solution... We were not successful using the K3 transceivers with a wide split so on those bands with wide splits (e;g., 9448/10128) we removed the K3 transceivers and substituted our old FT-1000MPs instead. They worked very well and were very easy to use. The K3 is far from easy to use in this application! As was suggested, operation of the K3 transceiver to meet our needs is much easier if we install a KBPF3 in each KRX3 subreceiver, since K3 operators almost always use their KRX3 sub receiver with SPLIT enabled, which forces the transmitter to transmit on the sub receive frequency. But a KRX3 sub receiver with no KBPF3 installed can't listen outside the ham bands where we transmit. So the commonly used SPLIT operation with the KRX3 can't meet our needs with our K3 transceivers with no KBPF3 installed in our KRX3 sub receivers If I had known not to tap SPLIT as I've always done when not transmitting on MARS frequencies, I may have been successful since we would then have been transmitting through the Main Receiver KBPF3 on the VFO A MARS frequency, and listening to the KRX3 sub receiver in the ham bands. I'll try split operation on 9448/10128 well before next year by not using SPLIT and listening on 10128 with the KRX3 sub receiver... Thanks Bob, 73 Frank W3LPL ----- Original Message ----- From: "Bob Wilson, N6TV" <n...@arrl.net> To: "Frank Donovan, W3LPL" <donov...@starpower.net>, "Elecraft Reflector" <Elecraft@mailman.qth.net> Sent: Monday, May 14, 2018 12:34:36 AM Subject: Re: [Elecraft] K3 Strange Power Output Problem On Sun, May 13, 2018 at 5:17 PM, < donov...@starpower.net > wrote: Its hard to devise a solution without this knowledge! Frank, It's also hard to suggest a solution without a clear understanding of the problem, which seems different than N3CW's original question. It's not clear to me what you need to achieve at NSS. I think you are saying you want listen to both widely-separated frequencies at the same time, using different antennas, one for the MAIN, one for the SUB? Or maybe you want to use the TX antenna for both receivers? Or maybe a separate RX antenna for both receivers? The SUB listens to either what is selected by MAIN (RX ANT or TX ANT) or to AUX, which is a totally separate RX ANT input that seems to bypass all the filters in the MAIN. With the SUB on, hold RX ANT to switch the SubRx to listen on AUX. This is a perfect input if your RX antenna is miles away from your TX antenna, which I assume is the case at NSS. Otherwise, if you want to listen to the TX ANT with both receivers, feed RX ANT OUT to both RX ANT IN and to AUX via an external 50 ohm splitter such as the Mini-Circuits ZFSC-2-6 , and now both receivers are listening to the same antenna, but with totally different receive paths. If you want to listen to a dedicated well-separated RX antenna in both receivers, instead of listening on the TX antenna , use an external splitter to feed the RX antenna to both RX ANT IN and to AUX. Repeating, do not use SPLIT mode, just tap SUB to TX on A, receive on both A and B, or just receive on B (CONFIG:L-MIX-R B B), whatever you require. 73, Bob, N6TV On Sun, May 13, 2018 at 4:45 PM, < donov...@starpower.net > wrote: <blockquote> Hi Wayne, The MARS to ham band K3 cross-band problem affects every band, but it was extremely severe on 30 meters because the NSS assigned frequency -- 9448 kHz -- was almost 700 kHz from our typical 10128 kHz receiving frequency. Since switching between the K3 bandpass filters and the KBPF3 band pass filters at T/R rates isn't a workable solution, how about this external BNC cable solution since my K3 transceivers have KRX3 sub receivers? If I understand the K3 internal receiver antenna switching correctly a single external BNC jumper cable allows the K3 to transmit and receive on VFO A on MARS frequencies and listen to any amateur band on the sub receiver: - Connect the RX ANT OUT connector to the RX ANT IN connector - Tap the main RX ANT button which connects ANT 1 to the RX ANT OUT connector and switches the input of the main receiver to the RX ANT IN connector (connected by the external BNC cable to RX ANT OUT) - Tap SUB to turn the sub receiver on - Hold BSET and tap ANT to set the sub receiver input to MAIN. This allows the subreceiver to listen on the RX ANT connected to the main receiver. I'm sorry I didn't think of this yesterday... tks 73 Frank W3LPL </blockquote> ______________________________________________________________ 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
