Eduard et all,here i share a short text about my 6.7 GHz receiver. Hope this is just begining of greater project, i'm looking forward to improve the receiver, and the shared info could be helpful.My greetings & regards, Dimitry UA3AVR.
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Hi all. Here the W3(OH) line 6.7 GHz yesterday. The weather was more quiet; some clouds, but it seems not too dense. The line doesn't reach the expected peak level >3000 Jy. There is a probability i strongly underestimated my Tsys (or overestimate the antenna performance) in the level calculations. But the lunar noise measurements do not indicate that (the Moon temperature 225 K with uniform distribution across the disk was taken as a reference). Is it a maser variability seen?With greetings®ards, Dimitry UA3AVR.
понедельник, 6 марта 2023 г. в 22:26:09 UTC+3, Eduard Mol:
Hi Dimitry,
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Hi Dimity,Thank you for sharing the information about your setup. Using the Terrasat components for downconversion is a nice approach. Following your recommendation I have ordered the item via ebay (the one not requiring modification). I could not find any further information about the device. In particular, I could not find what the voltage needs to be to power the device. Can you give any advice there?I am planning to do some lab tests with it as a preparation for a later methanol maser experiment. It will not be anytime soon as I still need to figure out what LNA to use or build, and then I still need a feedhorn. We will see how that goes.Best regards,Wolfgang
Am Montag, den 06.03.2023, 11:12 -0800 schrieb Dimitry UA3AVR:Eduard et all,here i share a short text about my 6.7 GHz receiver. Hope this is just begining of greater project, i'm looking forward to improve the receiver, and the shared info could be helpful.
My greetings & regards, Dimitry UA3AVR.--
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>>You still need to supply L.O. signal?
Yes, this module needs LO with levels 3-4 dBm.
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Hi Wolfgang, thanks,these data are important, but missing in the text, sorry. The nominal supply voltage for Terrasat downconverter is +5.5 V, single rail. My module works well with +5 V and without degrading in performance.
About LNA. I have ordered chips CMD283C3 for LNA, they works at 6.7 GHz with NF<0.8 dB; i think it is satisfactory. They need a simple PCB, a milled enclosure is available also. LNA with single FETs in the input stage could give NF less 0.5-0.6 dB, but stability and input VSWR of such stage is under questions. I would inform about progress in LNA building.
Feed design is a separate issue; i'm looking for low noise dual-mode feedhorn, possibly with septum (circular polarization). I think the feedhorn design is defined by reflector characteristics (the dish F/D). The best way is to manufacture the feed under a special project. Using feedhorns initially intended for 5.7 GHz EME may be problematic.
With greetings & regards, Dimitry UA3AVR.
среда, 8 марта 2023 г. в 13:57:51 UTC+3, fasleitung3:
Hi Dimity,Thank you for sharing the information about your setup. Using the Terrasat components for downconversion is a nice approach. Following your recommendation I have ordered the item via ebay (the one not requiring modification). I could not find any further information about the device. In particular, I could not find what the voltage needs to be to power the device. Can you give any advice there?I am planning to do some lab tests with it as a preparation for a later methanol maser experiment. It will not be anytime soon as I still need to figure out what LNA to use or build, and then I still need a feedhorn. We will see how that goes.Best regards,Wolfgang
Am Montag, den 06.03.2023, 11:12 -0800 schrieb Dimitry UA3AVR:Eduard et all,here i share a short text about my 6.7 GHz receiver. Hope this is just begining of greater project, i'm looking forward to improve the receiver, and the shared info could be helpful.
My greetings & regards, Dimitry UA3AVR.--
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Thanks, Dimitry, for the additional information.I am not sure when (or if at all) we will be able to do a 6 GHz methanol maser experiement. I still need to think whether it is doable to use one of our existing dishes. Our 10m dish would be ideal but it is a Cassegrain setup and therefore hard to modify of 6 GHz. We will see. The choice of the dish will obviously determine what feed we need ot build.Anyway, we will try out the downconversion first and then take from there...Wolfgang
Am Mittwoch, den 08.03.2023, 06:50 -0800 schrieb Dimitry UA3AVR:Hi Wolfgang, thanks,these data are important, but missing in the text, sorry. The nominal supply voltage for Terrasat downconverter is +5.5 V, single rail. My module works well with +5 V and without degrading in performance.
About LNA. I have ordered chips CMD283C3 for LNA, they works at 6.7 GHz with NF<0.8 dB; i think it is satisfactory. They need a simple PCB, a milled enclosure is available also. LNA with single FETs in the input stage could give NF less 0.5-0.6 dB, but stability and input VSWR of such stage is under questions. I would inform about progress in LNA building.
Feed design is a separate issue; i'm looking for low noise dual-mode feedhorn, possibly with septum (circular polarization). I think the feedhorn design is defined by reflector characteristics (the dish F/D). The best way is to manufacture the feed under a special project. Using feedhorns initially intended for 5.7 GHz EME may be problematic.
With greetings & regards, Dimitry UA3AVR.
среда, 8 марта 2023 г. в 13:57:51 UTC+3, fasleitung3:
Hi Dimity,Thank you for sharing the information about your setup. Using the Terrasat components for downconversion is a nice approach. Following your recommendation I have ordered the item via ebay (the one not requiring modification). I could not find any further information about the device. In particular, I could not find what the voltage needs to be to power the device. Can you give any advice there?I am planning to do some lab tests with it as a preparation for a later methanol maser experiment. It will not be anytime soon as I still need to figure out what LNA to use or build, and then I still need a feedhorn. We will see how that goes.Best regards,Wolfgang
Am Montag, den 06.03.2023, 11:12 -0800 schrieb Dimitry UA3AVR:Eduard et all,here i share a short text about my 6.7 GHz receiver. Hope this is just begining of greater project, i'm looking forward to improve the receiver, and the shared info could be helpful.
My greetings & regards, Dimitry UA3AVR.
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<6,7 GHz receiver project_2022-06-19.pdf>
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