MB8719 PLL - There is a neat trick that involves putting Pin 10 at exactly 1/2 VCC that tricks the divide by N encoder to add 192 instead of +64 or +128 to the N Code from the Channel Selector, have you tried it? I have long, long ago, it is tricky, but it works. You would either have +V (or isolated, internal pull-up) for +64, Ground for +128, or 1/2 VCC for +192.
It could be done with binary adders like 4008's, the last bit used would have to be biased 1/2 VCC, and either inverted first to correct the internal Pin 10 inversion and set up in a tristate mode.
Oh, and I would change the crystal to 11.1125 from a Washington or older single conversion MB8719 chassis to get proper band switching, "lowers and uppers".
It could be done with binary adders like 4008's, the last bit used would have to be biased 1/2 VCC, and either inverted first to correct the internal Pin 10 inversion and set up in a tristate mode.
Oh, and I would change the crystal to 11.1125 from a Washington or older single conversion MB8719 chassis to get proper band switching, "lowers and uppers".
Last edited:
