Message #8 Posted by Ellis Easley on 9 July 2003, 9:58 p.m.,
in response to message #7 by Johnny Billquist
61.25 MHz would be within US TV channel 3 (I believe it is 60-66 MHz) and I know the video carrier is near one end of the channel and the audio carrier is 4.5 MHz above the video, which would be 65.75 if I am correct. So I think that frequency refers to the RF modulator output and not the video output. It is true that the vertical frequency is very different but monitors with vertical hold and size adjustments usually have a lot of range, and since the horizontal frequency is almost identical (about 15.75 kHz), that part is no problem.
But I thought the PAL version of the 82163 didn't include an RF modulator. Also, I understand the RF frequency commonly used in the UK, at least, for connecting things to a TV was in the vicinity of US UHF TV channel 33 (around 584 MHz : [(channel - 14) * 6] + 470 MHz) - I first learned this from a friend who ordered the Sinclair 1000 as a kit from England and then later, found the same to be the case with my BBC Model B. Whatever the exact frequency, a TV with adjustable fine tuning can display the black and white signal as long as the vertical is also adjustable. But 62.25 MHz would still be within US TV channel 3.
US TV channels are all 6 MHz wide and are separated into three bands: 2-6 (VHF low) starting at 54 MHz, 7-13 (VHF high) starting at 174 MHz, and 14-69 (UHF) starting at 470 MHz. There used to be a channel 1 but the frequency was given to amateur radio. Also, there used to be UHF channels 70-83, I think those frequencies are now used for cell phones.