Hi all.
Exams are over and I've got some time to spare. What better way to start my holidays than with some electronics? My uni has a lot of flat, open fields, so I thought this would be a good opportunity to try something with some big (~8m dipole) antennas that I couldn't put up at home.
I've known about the Radio Jove project for some time now, but have been put off by the hard to find varicap and inductor values, and was wondering how to design a more 'modern' version. However, whilst I appreciate how this particular circuit works, and how a few different receivers work from my comms module, I do not know how to go about designing such a circuit. I did think about using one of those DTV USB dongles, but none seem to go down to such low frequencies.
I thought a good place to start would be to examine the Radio Jove specs, which can be found on the last page of this document:
http://radiojove.gsfc.nasa.gov/telescope/rcvr_manual.pdf
In short, we are after:
Gain >100dB
BW ~ 7kHz
NF 6dB
Aiming to tune around 20.1MHz
I think I get why most of the components are where they are, but there are some that throw me off and make me uncertain, for example the JFET on the RF input.
If anyone could help me get started, I would really appreciate it. Even if it is a case of focusing my efforts into one piece at a time (ie, you're going to need an input filter, go and design something that will filter between here and here, come back and show us for critique), I would really appreciate it.
Thanks alot for your time, it is really appreciated.
Regards,
Sparky
Exams are over and I've got some time to spare. What better way to start my holidays than with some electronics? My uni has a lot of flat, open fields, so I thought this would be a good opportunity to try something with some big (~8m dipole) antennas that I couldn't put up at home.
I've known about the Radio Jove project for some time now, but have been put off by the hard to find varicap and inductor values, and was wondering how to design a more 'modern' version. However, whilst I appreciate how this particular circuit works, and how a few different receivers work from my comms module, I do not know how to go about designing such a circuit. I did think about using one of those DTV USB dongles, but none seem to go down to such low frequencies.
I thought a good place to start would be to examine the Radio Jove specs, which can be found on the last page of this document:
http://radiojove.gsfc.nasa.gov/telescope/rcvr_manual.pdf
In short, we are after:
Gain >100dB
BW ~ 7kHz
NF 6dB
Aiming to tune around 20.1MHz
I think I get why most of the components are where they are, but there are some that throw me off and make me uncertain, for example the JFET on the RF input.
If anyone could help me get started, I would really appreciate it. Even if it is a case of focusing my efforts into one piece at a time (ie, you're going to need an input filter, go and design something that will filter between here and here, come back and show us for critique), I would really appreciate it.
Thanks alot for your time, it is really appreciated.
Regards,
Sparky