Quick question, what is the max power out can we get from LTM-1 and is there a possibility of adding an "external amplifier" to the stack? e.g. fits on QTH/QSH bus maybe and input is just the output of the transponder, picture your rig and the amp in your shack. No power supply considerations, just raw what if for the transponder. Thanks!
How many dB?
John...
On Mon, Jun 15, 2020, 15:32 Jerry Buxton via LTM ltm@amsat.org wrote:
Quick question, what is the max power out can we get from LTM-1 and is there a possibility of adding an "external amplifier" to the stack? e.g. fits on QTH/QSH bus maybe and input is just the output of the transponder, picture your rig and the amp in your shack. No power supply considerations, just raw what if for the transponder. Thanks!
-- Jerry Buxton, NØJY Vice President - Engineering Radio Amateur Satellite Corp. (AMSAT)
LTM mailing list LTM@amsat.org https://www.amsat.org/mailman/listinfo/ltm
The latest version of the LTM's RX/TX card that Dan is finishing up has two RF output power levels: 500 mW and 1W. When he's through testing, I've asked Dan to provide me with the DC power consumption numbers for all the possible modes (TLM only, Transponder Only, TLM + Transponder ----- for High and Low power settings). We know Linear Amplifiers are NOT very power efficient. So I'm expecting this high power mode will require in excess of 3W DC..............we'll see.
As for adding an external amplifier to the 'stack', as JK asked, what is the final RF power level desired? Config-wise one could certainly connect the existing TX coax from the RX/TX card to a stack-mounted amplifier card and control it via QTH/QSH bus signals. But the design requirements would have to be specified and there would be several design challenges and trade-offs. I mentioned DC power consumption for low efficiency linear PAs. Beyond that I would be concerned about RFI effects on other cards in the stack, particularly experiments. Also, heat dissipation is a real challenge were the requirement to be several watts of RF, i.e., thermal issues. Lastly, I'd be concerned re meeting IM levels, i.e., spectral purity requirements from the ITU regulations.
eric
On Mon, Jun 15, 2020 at 4:32 PM Jerry Buxton via LTM ltm@amsat.org wrote:
Quick question, what is the max power out can we get from LTM-1 and is there a possibility of adding an "external amplifier" to the stack? e.g. fits on QTH/QSH bus maybe and input is just the output of the transponder, picture your rig and the amp in your shack. No power supply considerations, just raw what if for the transponder. Thanks!
-- Jerry Buxton, NØJY Vice President - Engineering Radio Amateur Satellite Corp. (AMSAT)
LTM mailing list LTM@amsat.org https://www.amsat.org/mailman/listinfo/ltm
Yeah, it really isn't worth the effort for 2 or 3 dB more.
If one had the power and heat dissipation capability for +40 dBm (10 dB more) , now you're talking.
Yes, it could probably fit on the QSH/QTH stack, though. Heat dissipation *would* be an issue.
73
John... WB4LNM
On Mon, Jun 15, 2020 at 11:04 PM Eric Skoog via LTM ltm@amsat.org wrote:
The latest version of the LTM's RX/TX card that Dan is finishing up has two RF output power levels: 500 mW and 1W. When he's through testing, I've asked Dan to provide me with the DC power consumption numbers for all the possible modes (TLM only, Transponder Only, TLM + Transponder ----- for High and Low power settings). We know Linear Amplifiers are NOT very power efficient. So I'm expecting this high power mode will require in excess of 3W DC..............we'll see.
As for adding an external amplifier to the 'stack', as JK asked, what is the final RF power level desired? Config-wise one could certainly connect the existing TX coax from the RX/TX card to a stack-mounted amplifier card and control it via QTH/QSH bus signals. But the design requirements would have to be specified and there would be several design challenges and trade-offs. I mentioned DC power consumption for low efficiency linear PAs. Beyond that I would be concerned about RFI effects on other cards in the stack, particularly experiments. Also, heat dissipation is a real challenge were the requirement to be several watts of RF, i.e., thermal issues. Lastly, I'd be concerned re meeting IM levels, i.e., spectral purity requirements from the ITU regulations.
eric
On Mon, Jun 15, 2020 at 4:32 PM Jerry Buxton via LTM ltm@amsat.org wrote:
Quick question, what is the max power out can we get from LTM-1 and is there a possibility of adding an "external amplifier" to the stack? e.g. fits on QTH/QSH bus maybe and input is just the output of the transponder, picture your rig and the amp in your shack. No power supply considerations, just raw what if for the transponder. Thanks!
-- Jerry Buxton, NØJY Vice President - Engineering Radio Amateur Satellite Corp. (AMSAT)
LTM mailing list LTM@amsat.org https://www.amsat.org/mailman/listinfo/ltm
LTM mailing list LTM@amsat.org https://www.amsat.org/mailman/listinfo/ltm
I couldn’t agree more, John.
73, Marc N2UO
On Jun 16, 2020, at 1:21 PM, John Klingelhoeffer via LTM ltm@amsat.org wrote:
Yeah, it really isn't worth the effort for 2 or 3 dB more.
If one had the power and heat dissipation capability for +40 dBm (10 dB more) , now you're talking.
Yes, it could probably fit on the QSH/QTH stack, though. Heat dissipation would be an issue.
73
John... WB4LNM
On Mon, Jun 15, 2020 at 11:04 PM Eric Skoog via LTM ltm@amsat.org wrote: The latest version of the LTM's RX/TX card that Dan is finishing up has two RF output power levels: 500 mW and 1W. When he's through testing, I've asked Dan to provide me with the DC power consumption numbers for all the possible modes (TLM only, Transponder Only, TLM + Transponder ----- for High and Low power settings). We know Linear Amplifiers are NOT very power efficient. So I'm expecting this high power mode will require in excess of 3W DC..............we'll see.
As for adding an external amplifier to the 'stack', as JK asked, what is the final RF power level desired? Config-wise one could certainly connect the existing TX coax from the RX/TX card to a stack-mounted amplifier card and control it via QTH/QSH bus signals. But the design requirements would have to be specified and there would be several design challenges and trade-offs. I mentioned DC power consumption for low efficiency linear PAs. Beyond that I would be concerned about RFI effects on other cards in the stack, particularly experiments. Also, heat dissipation is a real challenge were the requirement to be several watts of RF, i.e., thermal issues. Lastly, I'd be concerned re meeting IM levels, i.e., spectral purity requirements from the ITU regulations.
eric
On Mon, Jun 15, 2020 at 4:32 PM Jerry Buxton via LTM ltm@amsat.org wrote: Quick question, what is the max power out can we get from LTM-1 and is there a possibility of adding an "external amplifier" to the stack? e.g. fits on QTH/QSH bus maybe and input is just the output of the transponder, picture your rig and the amp in your shack. No power supply considerations, just raw what if for the transponder. Thanks!
-- Jerry Buxton, NØJY Vice President - Engineering Radio Amateur Satellite Corp. (AMSAT)
LTM mailing list LTM@amsat.org https://www.amsat.org/mailman/listinfo/ltm
LTM mailing list LTM@amsat.org https://www.amsat.org/mailman/listinfo/ltm
LTM mailing list LTM@amsat.org https://www.amsat.org/mailman/listinfo/ltm
I have at least one preliminary number for power consumption. I have the PA, drivers, and DC-DC part of the APT circuit running now. I can get about 2W (with two 1W signals) average power out of it. It draws about 6W to do this and does get a bit warm. This is for running at that power continuously.
73, Dan W9EQ
On Tue, Jun 16, 2020 at 1:49 PM Marc Franco via LTM ltm@amsat.org wrote:
I couldn’t agree more, John.
73, Marc N2UO
On Jun 16, 2020, at 1:21 PM, John Klingelhoeffer via LTM ltm@amsat.org wrote:
Yeah, it really isn't worth the effort for 2 or 3 dB more.
If one had the power and heat dissipation capability for +40 dBm (10 dB more) , now you're talking.
Yes, it could probably fit on the QSH/QTH stack, though. Heat dissipation *would* be an issue.
73
John... WB4LNM
On Mon, Jun 15, 2020 at 11:04 PM Eric Skoog via LTM ltm@amsat.org wrote:
The latest version of the LTM's RX/TX card that Dan is finishing up has two RF output power levels: 500 mW and 1W. When he's through testing, I've asked Dan to provide me with the DC power consumption numbers for all the possible modes (TLM only, Transponder Only, TLM + Transponder ----- for High and Low power settings). We know Linear Amplifiers are NOT very power efficient. So I'm expecting this high power mode will require in excess of 3W DC..............we'll see.
As for adding an external amplifier to the 'stack', as JK asked, what is the final RF power level desired? Config-wise one could certainly connect the existing TX coax from the RX/TX card to a stack-mounted amplifier card and control it via QTH/QSH bus signals. But the design requirements would have to be specified and there would be several design challenges and trade-offs. I mentioned DC power consumption for low efficiency linear PAs. Beyond that I would be concerned about RFI effects on other cards in the stack, particularly experiments. Also, heat dissipation is a real challenge were the requirement to be several watts of RF, i.e., thermal issues. Lastly, I'd be concerned re meeting IM levels, i.e., spectral purity requirements from the ITU regulations.
eric
On Mon, Jun 15, 2020 at 4:32 PM Jerry Buxton via LTM ltm@amsat.org wrote:
Quick question, what is the max power out can we get from LTM-1 and is there a possibility of adding an "external amplifier" to the stack? e.g. fits on QTH/QSH bus maybe and input is just the output of the transponder, picture your rig and the amp in your shack. No power supply considerations, just raw what if for the transponder. Thanks!
-- Jerry Buxton, NØJY Vice President - Engineering Radio Amateur Satellite Corp. (AMSAT)
LTM mailing list LTM@amsat.org https://www.amsat.org/mailman/listinfo/ltm
LTM mailing list LTM@amsat.org https://www.amsat.org/mailman/listinfo/ltm
LTM mailing list LTM@amsat.org https://www.amsat.org/mailman/listinfo/ltm
LTM mailing list LTM@amsat.org https://www.amsat.org/mailman/listinfo/ltm
So, what's the continuing discussion / question, boss? Where do we go from here? The question was kina open ended without a discussion of a particular mission / bus.
73
John... WB4LNM
On Tue, Jun 16, 2020 at 8:37 PM Dan Habecker dan.habecker@gmail.com wrote:
I have at least one preliminary number for power consumption. I have the PA, drivers, and DC-DC part of the APT circuit running now. I can get about 2W (with two 1W signals) average power out of it. It draws about 6W to do this and does get a bit warm. This is for running at that power continuously.
73, Dan W9EQ
On Tue, Jun 16, 2020 at 1:49 PM Marc Franco via LTM ltm@amsat.org wrote:
I couldn’t agree more, John.
73, Marc N2UO
On Jun 16, 2020, at 1:21 PM, John Klingelhoeffer via LTM ltm@amsat.org wrote:
Yeah, it really isn't worth the effort for 2 or 3 dB more.
If one had the power and heat dissipation capability for +40 dBm (10 dB more) , now you're talking.
Yes, it could probably fit on the QSH/QTH stack, though. Heat dissipation *would* be an issue.
73
John... WB4LNM
On Mon, Jun 15, 2020 at 11:04 PM Eric Skoog via LTM ltm@amsat.org wrote:
The latest version of the LTM's RX/TX card that Dan is finishing up has two RF output power levels: 500 mW and 1W. When he's through testing, I've asked Dan to provide me with the DC power consumption numbers for all the possible modes (TLM only, Transponder Only, TLM + Transponder ----- for High and Low power settings). We know Linear Amplifiers are NOT very power efficient. So I'm expecting this high power mode will require in excess of 3W DC..............we'll see.
As for adding an external amplifier to the 'stack', as JK asked, what is the final RF power level desired? Config-wise one could certainly connect the existing TX coax from the RX/TX card to a stack-mounted amplifier card and control it via QTH/QSH bus signals. But the design requirements would have to be specified and there would be several design challenges and trade-offs. I mentioned DC power consumption for low efficiency linear PAs. Beyond that I would be concerned about RFI effects on other cards in the stack, particularly experiments. Also, heat dissipation is a real challenge were the requirement to be several watts of RF, i.e., thermal issues. Lastly, I'd be concerned re meeting IM levels, i.e., spectral purity requirements from the ITU regulations.
eric
On Mon, Jun 15, 2020 at 4:32 PM Jerry Buxton via LTM ltm@amsat.org wrote:
Quick question, what is the max power out can we get from LTM-1 and is there a possibility of adding an "external amplifier" to the stack? e.g. fits on QTH/QSH bus maybe and input is just the output of the transponder, picture your rig and the amp in your shack. No power supply considerations, just raw what if for the transponder. Thanks!
-- Jerry Buxton, NØJY Vice President - Engineering Radio Amateur Satellite Corp. (AMSAT)
LTM mailing list LTM@amsat.org https://www.amsat.org/mailman/listinfo/ltm
LTM mailing list LTM@amsat.org https://www.amsat.org/mailman/listinfo/ltm
LTM mailing list LTM@amsat.org https://www.amsat.org/mailman/listinfo/ltm
LTM mailing list LTM@amsat.org https://www.amsat.org/mailman/listinfo/ltm
participants (5)
-
Dan Habecker -
Eric Skoog -
Jerry Buxton -
John Klingelhoeffer -
Marc Franco