SatSig topic:

Spectrum Analyzer FSH3

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Nov 11^th, 2007 at 3:34pm

I need help; I am using Spectrum Analyzer FSH3 100 kHz - 3 G Hz. my antenna is Prodelin 3.8M Tx/Rx C-Band Antenna. The RX IF from the LNB directly connects to the Modem.

When I connect the RX cable from the LNB to the Spectrum RF input, nothing is changed.

How can I use the Spectrum analyzer properly ?

Regards,

Nov 11^th, 2007 at 6:46pm

You need a broadband 2 way (3 dB) splitter, perhaps 5 - 2050 MHz.

The input of the splitter goes to the LNB.
The DC pass output from the splitter goes to the modem (which will provide the DC power to the LNB).
The other output goes to the spectrum analyser (signals only).

2-way and 4-way splitters look like this:

Splitters may be permanently installed to allow several receive modems to be connected, or in service spectrum measurements to be made without interrupting service.

You can buy such Splitters/Combiners from Sadoun.com

Once you get to see the spectrum note that C band LNBs normally have a local oscillator frequency of 5150 MHz and the output frequency spectrum is therefore inverted. ref: Explanation and description of LNB

Best regards, Eric.

Nov 12^th, 2007 at 8:14am

Dear Eric,

Thanks for your instructions. it is really very helpful.

Nov 12^th, 2007 at 7:16pm

Dear Eric ;
is this analyzer for c - Band only ?
can it read the sat name with the spectrum Graph ?
how do you evaluate it ? is it recommended type while the satlook analyzer more known .
also what do you think about the new promax TV Explorer II ?
with regards
Ahmed

Nov 12^th, 2007 at 11:01pm

The FSH3 is a superb portable spectrum analyser with an input range up to 3 GHz.

You can use it for C band downlink measurements if you have a C band LNB connected. The range of frequencies into the analyser will be approx 950 - 1750 MHz

You can use it for Ku band downlink measurements if you have a Ku band LNB connected. The range of frequencies into the analyser will be approx 950 - 2150 MHz

It is also of use for direct measurement of 70 MHz and 140 MHz IF frequencies and transmit L band signals on their way to the BUC.

When you are using an LNB you will need a separate source of 13/19volts DC and possibly 22kHz tone to power the LNB plus a splitter to inject the power and tone. Make sure your spectrum analyser model is protected against DC accidentally applied to the input port, either that or always use a DC block on the spectrum analyser input.

The advantage of the SATLOOK is that it has an internal DC supply for a satellite LNB with 22kHz tone option and 13/19volts option. I've never seen a Promax TV explorer 2. Maybe someone else could help ?.

Best regards, Eric.

Jan 27^th, 2008 at 1:24am

if you did not find the spliters that Eric told you about you can also take the loop out from any home reciever and it will do the job .with recpect to the c band you have only to callculate the lnb oscillater from the frequency for example 5150-4040=1110MHz it is very easy because all the time that you want to fix a dish you will have a receiver and monitor in front of you to make sure that you are with the right sat or you have to use the splitter that Eric told you about and make sure that it is a power pass splitter it has red lines as Mr Eric send to you that picture for it.