Hi,
I developed an alternative software for the "138M-4.4G USB SMA Source/Simple Spectrum Analyzer/Signal Generator" sold at eBay.
More info here:
https://www.eevblog.com/forum/testgear/presenting-my-new-software-for-the-sma-spectrum-analyzer-138mhz-4-4ghz/and
http://vma-satellite.blogspot.pt/One of the problems I have with it, is that I (and possibly others) want to monitor the spectrum of satellite dishes using common C-band or Ku-band LNB's.
These normally use 13V/18V (sometimes 14V/18V, doesn't matter) to switch V/H polarisation and 0kHz/22kHz t switch L/H band.
On top of this, DiSEqC commands, modulated in 22kHz, are used to switch accessories like multiswitches, motors, etc.
Right now, I use the Loop-Through connector of a satellite dish to feed the SMA Simple Spectrum Analyser. WARNING: You need to use a DC blocker to do that! Do NOT connect the device directly, as you will kill the ADF4350 IC.
What would really be great, would be a small device with the following features:
1) SMA Input Connector to attach the SMA Simple Spectrum Analyser
2) F-Type Connector to attach the LNB
3) Internal rechargeable battery to drive the LNB
4) LED's to show 13V/18V and 0kHz/22kHz (let's forget about DiSEqC in the first version)
5) 2 buttons to switch 13V/18V and 0kHz/22kHz
6) Built-in DC blocker on the SMA connector
This would be the minimum specs.
The better (second) version, should:
1) Connect through USB/RS232 to the PC
2) Allow remote setting of polarity and band
3) Support DiSEqC commands from PC
This would be the final version.
My problem is, that I have much to little electronics knowledge to build this myself and I need help:
1) How to I generate 13V/18V from i.e. a 12V battery?
2) How to I generate a 22kHz Signal and mix it on the F-Type connector?
3) How to best make the buttons and LED work?
4) How to make the DC blocker? Is a simple diode enough? What type?
I am not considering the 50 Ohm/75 Ohm impedance issue, as I think it is irrelevant precision-wise. Am I overlooking anything?
Anyone interested in this project?
Basically, I would like to build something similar (equal) to this:
http://shop.sat-kabel.de/mess-und-prueftechnik/messgeraetezubehoer/geraeteschutz-aufbewahrung/26/akkuteil-au-spm?c=12Regards,
Vitor