Uniden 780 bandwidth for FM, NFM & WFM

[brian95008]

Hi all,

Does anyone know the bandwidths for the Uniden 780 when selecting FM, NFM and WFM modes. I want to select the proper mode that gives me as close to 40 KHz of bandwidth as possible.

Thanks,
Brian
Campbell, CA

 

[mciupa]

NFM = +/- 2.5 kHz
FM = +/- 5.0 kHz
WFM = +/- 50.0 kHz

 

[pro92b]

From the BC780 circuit description document saved from the FCC site:

FM/AM Mode IF: 450 kHz (BW: +/-10 kHz)
NFM Mode IF: 450 kHz (BW: +/-6kHz)

The WFM bandwidth was not listed but standard FM broadcast is +/-75 kHz

 

[Voyager]

From the BC780 circuit description document saved from the FCC site:

FM/AM Mode IF: 450 kHz (BW: +/-10 kHz)
NFM Mode IF: 450 kHz (BW: +/-6kHz)

The WFM bandwidth was not listed but standard FM broadcast is +/-75 kHz

BW for WFM should be on the order of +/- 200 kHz.

The lower numbers posted above are for standard deviations, not receiver bandwidth.

Their FM (NBFM in the rest of the industry) specs look a little wide. I would think it should be +/- 8 kHz (not 10). That's the standard BW for most commercial radios. Standard FM is rare, but is +/- 25-30 kHz. Only the Military and some ham links use standard FM. No receiver I know of supports that mode, but you can use WFM and receive it - albeit at a somewhat low level of audio.

Joe M.

 

[pro92b]

Scanners are not as precise as commercial radios and almost all recent Uniden and GRE models have a +/-10 kHz filter.

A Texas Instruments design book I have suggests a +/-130 kHz bandwidth for FM broadcast receiver design. The +/-200 kHz figure does seem unusually wide. Uniden did not publish their bandwidth figure for WFM.