Well first off, your set uses the old 24 mc IF (vs. the later standardized 45 mc IF). Superhet theory dictates that your set's local oscillator (LO) has to run at 24 mc above the received signal's frequency. Channel 3 video carrier is 61.25 mc. So, 61.25 + 24 = 85.25 mc for the LO. The two signals are mixed, yielding the 'beat' or Intermediate Frequency of 24 mc.
Since the video information on the carrier occupies a wide band width, the IF response must also be broad band, occupying a wide swatch on either side of 24 mc. That's why the IF strip is stagger tuned with an extra stage or two of amplification.
In contrast, a radio's IFs are tuned 'on peak' since audio bandwidth is all that's needed. Since the IFs are not staggered, less amplification is needed.
In a typical AM radio, the LO tracks 455 kc above the received signal, yielding the 455 kc IF. Most all FM radios use 10.7 mc for the IF, meaning the LO tracks 10.7 mc above the received signal.
Most all consumer gear uses 'high side' LO injection, meaning the LO runs above the received frequency. Some specialized communications gear may occasionally use low side injection.
Here's a listing of TV channel frequencies..
http://wiki.radioreference.com/index...on_Frequencies