In reference to the KH6HTV amps, since they are not bidirectional, you will need to properly sequence the transition from TX to RX with the control of the antenna relay. The microwave users have developed some excellent solutions to do this that can be easily used to prevent problems. An example of these is the M2 model S3 unit, https://www.m2inc.com/FGS3, or the W6PQL design, https://www.w6pql.com/relay_sequencer.htm
The key thing with sequencers is that you do not want to run the amp when it is disconnected from a load or if it is connected to the receiver. Inline LNAs also need protection from high level RF.
Jim - Is a sequencer necessary when it's the amplifier is connected to a transmit-only connection on the radio (and of course, assuming a dedicated antenna or a duplexer / triplexer? I've seen some SDR units, especially with the ADALM-PLUTO that provide a PTT signal to key the amplifier, and the KH6HTV amplifiers have a PTT input that can be used for such signals.
A lot depends on getting the amp turned off before the tx/rx relay to the antenna switches state. Depending upon the construction of that antenna relay, it could present either a grounded short or an open, not to mention you are hot switching the relay if that amp is not turned off... None of those conditions are good. Modern transceivers have that sort of sequencing built in, but if you are using separate units, it is up to the user to provide the correct control. All this can happen in milliseconds or less with a good sequencer.
This is not as important in a situation like a repeater with a duplexor or crossband diplexor as it is designed to have both the RX and TX running at the same time.
Seems like that repeater speech transcribing system would be a good application for ka9q-radio. Since January 2021 I have been recording every ham FM channel I can hear in San Diego on the 2m, 125cm and 70cm bands. Compressed with Opus it's a little less than 1 TB/year. More recently I added 6m and 10m. Want to give your transcribers a real workout?
I have been planning on setting up a system where users can FTP Audio In and Get same data out on a dashboard this could be a perfect stress test for this setup.
Regarding the DB0UV SSB->FM repeater, the multi-input roundtable repeater is another function that I've been playing with in ka9q-radio. DB0UV design is simple and elegant: ssb is linear modulation sowhen two stations transmit at the same time your hear the sum of their audio, not the garbled mess you get with FM.
But there's still a way to use FM, provided each user has his own input channel with the audio summed at the repeater. I did a proof of concept in ka9q-radio a few years ago with an eye to proposing it for the ISS, where the drawbacks of a single-channel FM uplink are rather apparent. With my scheme the repeater receives a bunch of FM channels, sums their audio and retransmits it with the usual CWID and transmitter tail. You just pick one input at random, and if it's already in use, try another. This idea dates back to the Pacsat design of the late 1980s, with four uplink receivers and one downlink transmitter. Those four receivers were in hardware; when you do them in software you can have many more.
Phil - The multi-channel input capability of ka9q-radio is the basic technology I was imagining for my SuperPeater concept, including providing multiple data (and digital voice) formats on separate input channels.
Of course using this for FM is really just a proof of concept. Digital is the right way to go. After after a lot of work we could even recreate our own version of Zoom...
If I could move anywhere based only on ham radio activity, it would absolutely be the Seattle area. Nice to see Meshcore beginning to get some high-profile use.
In reference to the KH6HTV amps, since they are not bidirectional, you will need to properly sequence the transition from TX to RX with the control of the antenna relay. The microwave users have developed some excellent solutions to do this that can be easily used to prevent problems. An example of these is the M2 model S3 unit, https://www.m2inc.com/FGS3, or the W6PQL design, https://www.w6pql.com/relay_sequencer.htm
The key thing with sequencers is that you do not want to run the amp when it is disconnected from a load or if it is connected to the receiver. Inline LNAs also need protection from high level RF.
Jim W6US
Jim - Is a sequencer necessary when it's the amplifier is connected to a transmit-only connection on the radio (and of course, assuming a dedicated antenna or a duplexer / triplexer? I've seen some SDR units, especially with the ADALM-PLUTO that provide a PTT signal to key the amplifier, and the KH6HTV amplifiers have a PTT input that can be used for such signals.
Good question!
A lot depends on getting the amp turned off before the tx/rx relay to the antenna switches state. Depending upon the construction of that antenna relay, it could present either a grounded short or an open, not to mention you are hot switching the relay if that amp is not turned off... None of those conditions are good. Modern transceivers have that sort of sequencing built in, but if you are using separate units, it is up to the user to provide the correct control. All this can happen in milliseconds or less with a good sequencer.
This is not as important in a situation like a repeater with a duplexor or crossband diplexor as it is designed to have both the RX and TX running at the same time.
Jim W6US
Seems like that repeater speech transcribing system would be a good application for ka9q-radio. Since January 2021 I have been recording every ham FM channel I can hear in San Diego on the 2m, 125cm and 70cm bands. Compressed with Opus it's a little less than 1 TB/year. More recently I added 6m and 10m. Want to give your transcribers a real workout?
I have been planning on setting up a system where users can FTP Audio In and Get same data out on a dashboard this could be a perfect stress test for this setup.
What audio formats can you handle?
Regarding the DB0UV SSB->FM repeater, the multi-input roundtable repeater is another function that I've been playing with in ka9q-radio. DB0UV design is simple and elegant: ssb is linear modulation sowhen two stations transmit at the same time your hear the sum of their audio, not the garbled mess you get with FM.
But there's still a way to use FM, provided each user has his own input channel with the audio summed at the repeater. I did a proof of concept in ka9q-radio a few years ago with an eye to proposing it for the ISS, where the drawbacks of a single-channel FM uplink are rather apparent. With my scheme the repeater receives a bunch of FM channels, sums their audio and retransmits it with the usual CWID and transmitter tail. You just pick one input at random, and if it's already in use, try another. This idea dates back to the Pacsat design of the late 1980s, with four uplink receivers and one downlink transmitter. Those four receivers were in hardware; when you do them in software you can have many more.
Phil - The multi-channel input capability of ka9q-radio is the basic technology I was imagining for my SuperPeater concept, including providing multiple data (and digital voice) formats on separate input channels.
Of course using this for FM is really just a proof of concept. Digital is the right way to go. After after a lot of work we could even recreate our own version of Zoom...
If I could move anywhere based only on ham radio activity, it would absolutely be the Seattle area. Nice to see Meshcore beginning to get some high-profile use.
Cale - We'd love to have you in closer proximity! Your unique contribution would be a great addition!