The thing with the public interest channels is that each satellite has to carry its own load of the mandated channels. You cannot have all the PI channels on one location. Initially Dish tried this. They petitioned the FCC to allow them to have a "free educational package" at 61.5 that would have consited of all the PI channels. The FCC stuck to its guns and said that each satellite had to carry its load of PI channels.
Right now 9405 The Pentagon Channel, 9406 Classic Arts Showcase, 9416 Good Samaritan Network, 9417 Holistic Television Network, and 9418 Panhandle Area Educational Consortium are the PI channels at 61.5 and 148.
Eseentially, no matter what PI channels get stuck over at 61.5 and 148 (which are allowed to duplicate since no single customer would have both for DISH programming (Sky Angel is not Dish!) some one would be very unhappy because "their" channel is in the "wrong" place.
From
http://ekb.dbstalk.com/49
Here are the rules for PI channels:
4-7% of the channel capacity must be reserved for PI channels (The key here is "reserved", other channels may use the reserved space until a PI channel becomes available).
If the percentage of reserved space results in a fraction the number of PI channels are rounded up (IE: if 4% is 2.35 channels the provider needs to carry 3 channels. Basically there is 1 PI channel for every 25 channels).
The percentage is determined by the average of the channels offered in the previous year with channel counts taken once per quarter (IE: the number of PI channels in 2003 are based on 2002 channel counts).
PI channels must not be charged more than the wholesale charge for carrying the channel.
Only 1 channel from an entity may be carried as PI unless all PI channels in the country have been given an oppurtunity to be carried (this will never occur as there are more PI channels than space).
PI channels may not be edited by the provider nor may the provider have any interest in the channel (IE: the provider can't own all or a part of the channel).
PI channels are to be treated like all other channels in the line-up and are to be given the same treatment (IE: channels are to be given the same amount of bandwidth as other channels).
A variety of channels with a variety of viewpoints must be carried (IE: you have to carry more than just religious PI channels).
The PI channels must be offered to every subscriber free regardless of package (E* intreprets subscribers as those with AT-50 or higher, anyone with less isn't a subscriber, but a customer. D* makes their PI channels available to everyone regardless of programming level).
To qualify as a PI channel the channel must be non-commercial and owned by a non-profit or government entity.