Hello everyone. I am very confused about the DTV transition and need some help please.

I reside in Los Angeles county, California.

1. My TV has an ATSC tuner, so getting a converter box will not help in any way to receive digital channels or more digital channels, right?

2. When I auto program my TV to scan the air, I sometimes get more digital channels, and sometimes less digital channels. Normally, within channels 2-13, I only get 5.1 fine (KTLA). In the upper channels, I get a few Asian/Hispanic ones (e.g. 22.1, 22.2) and Christian church channels (40.1, 40.2, 40.3).

The rest of the major stations like 2 (CBS), 7 (ABC), 11 (Fox) are always in analog -- does that mean I will lose them after the transition or will these analog broadcasts (2.0, 4.0, 7.0, 11.0, etc) convert to digital? In other words, the power used to broadcast in analog will be digital?

A few weeks ago ABC ran a two-minute test and it said I need a converter box... but my TV has a ATSC tuner which I read is like a converter box.

I should also note that I live in an apartment complex (I think called a "garden apartment") and there is 1 roof antenna shared among 20 units. Perhaps this is somewhat (or entirely?) responsible for my DTV trouble?

Appreciate any advice. Thanks in advance!