[aprssig] Yaesu FT1500M

[Stephen H. Smith]

scott at opentrac.org wrote:

>>(Channel "E" on analog cable systems lands almost directly on 144.39)
>>    
>>
>
>Huh... my cable-ready TV only gets numbered channels.
>
>  
>
In traditional analog cable systems, the first 12 channels (2-13) are 
usually on the same frequencies as their off-the-air counterparts.   To 
carry more than 12 channels, the the cable operator starts filling in 
the spectrum between the upper edge of the VHF low-band (channel 6 upper 
edge is 88MHz) and the lower edge of the VHF highband (channel 7 lower 
edge is 174MHz) with additional 6 MHz TV channels.  

These show up on your cable-ready tuner (or cable box) as channels 14-28 
although their RF frequencies are totally different from the channels 
14-28 in the  "real" over-the-air UHF band.  [This is why TVs/VCRs/etc 
have "cable" vs "antenna" selectors.] The reason for this is to keep the 
added channels, sometimes referred to as "mid-band" channels,  in the 
VHF range instead of in the UHF range where the cable losses would be 
far higher. ]
Within the industry, these added channels that don't correspond to 
actual RF channels are often designated with letters instead of numbers.




Stephen H. Smith             wa8lmf (at) aol.com
                                                    
Home Page:                   http://wa8lmf.com

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