We got directv at our new house today and the older tv we got that I mounted outside does not have an hdmi input, but the smaller receiver we got with directv has an "av out" slot...would this be a suitable substitute for and hdmi or av component cable?

The AV out, is it RCA (red,white,yellow)? Since you don't have HDMI, that would be what you need to connect

If it is what AtlAg05 asked about - yes that will send video and audio to the new TV. The yellow connector carry the video. That is called a "composite" video signal and it is analog.

I assume that TV is high definition and it probably has "component" (red/green/blue) video connections (the standard for HD before DVI and HDMI). Composite video is not HD. It is an analog signal and will look noticeably worse than HDMI or component connections.

I have an av out cord that goes to one of the smaller directv receivers and it has component video up to 1080i capability. I had to buy that cord separately though. look on eBay for component and the model number of receiver you have.

If you have a client receiver "mini genie" in that room you need a 10-pin/ component or 10-pin/ composite cable...If it's a regular HD receiver "H24" or "H25" the standard yellow red white composite "RCA" cables will do