Need a "Mitsubishi HD-1080 HDTV Receiver" to convert my TV to HD

You con't need to buy anything other than a HD satellite or cable box. A television can either handle HD or not.  The high definition sets are monitors that are capable of handing an input of up to 1080i. 
Quick and dirty. Look in the back for blue, green, red cable input sockets. There should be matching cable outs. from your cable or satellite box. get a set of  component video cables, plug them in. Determine the audio type, where RCA jacks, Toslink fiberoptic or a component cable sock. In the latter you use a cable much like a yellow video. You can get away with using a yellow video cable if need be. Now, below more specifics if needed.

No, you don't want to by the add-on from Mitsubishi.  I am assuming you have a 16-9 wide format box  
If you have a squarish box, i.e. 4:3 ratio. forget it. I don't know if any wree made for HD, but unlikely.  If you'd given me the model number could be a little more definitive. If you have a manual, it will tell you whether you can go HDTV.  
Take a look in the rear of the set and look at  the connection holes. You should have at least one set of inputs, marked in some way with the Red, Green and Blue just on the inside of the cable hole. Those are tomponent cables pops that allow you to do high definition television. These cables are video only.; Sound is a second separate question. 
There are usually some other assorted things back there, including off air tele.and maybe another kind of connecter.. Some of these might be useful if you have games etc. that attach directly to the set. In any event, those component cables say that you can  do HDTV. (NB: 
The Direct TV  HD box should have component cable outputs. You can do this directly from the DiTV box to the set. You would also need a separate Audio Cable(s). Your set should have either a toslink fiberoptic hookup and/or a component audio cable. There's no inherent advantage between those two. If you have an old video cable (yellow) than you can substitute that. 
You should now have HDTV and high quality sound through the set. You will probably have to set up the inputs and other stuff with the.remote. It's pretty logical. If you have used input x for bringing in the video, just match it up.and your on your way. 
If you are going to confuse things by trying to connect another piece of gear, e.g. dvd box, you would go to inputs two. If you have the second set of component input, then hook an HD player to it. In this setup, you adjust the sound on the set according to how it works. I assume the DTV audiio can be controlled directly just as a cable box.  -- Here's what's going on. For several years Mitsubishi built higher end televisions without tuners or slots for cable (or satellite). But they were HD capable (as I said, not all). At the time, there was no HD that mattered and not even much of a standard for it. Some wanted 729p, others wanted 1080i The advantage for 720p over 1080i was supposedly the improved movement capture. 720p isn't dead, but it's not a problem. 
You will need to set the menu on the television (using the remote) so that it says 1080i. It does not do 1080p, the newer high standard. It only has two other settings of consequence, 480i and 480p. Put it on 1080i and leave it alone. The 480i and the 480P will be on auto pilot if you have an older DVD players. If there is a high definition signal at fewer than 1080, it will be upconverted to 1080i.. 
The set will handle any signal you send it like that. You probably have an HDMI  out from your dtv or cable box. The set does not have HDMI (unless on a later model). The DTV box should have both of them. That's a simpler wiring setup that allows 1080P. On the offchance you have a box HDMI only, you'll need a converter cable.
The setup gets a little more  complicated if you're using a receiver as a switcher, i.e. all inputs go there with only one output to the set. when ou do that you're in an area outside this question. 
  is this all there is to it. But It goes only slightly more difficult if you're hooking up the   . 


You don't need the box for the television set. 

I have a HD-1080 Receiver. [email protected]

I've got a Mitsubishi HD1080 receiver (this requires the 15 pin D connector for control from the TV, and has 5 BNC connectors (red, green, blue, H, and V). If this is what you need, let me know. I've got no use for it, I'm sure we can come to a agreeable price

Cable company is what I went with. You'll need a cox cable anyways if you want to record television.

I have a few of them, brand new. Contact me. Guarantee cheapest

I have one. $20? hit me up.

If you are still looking for this i have 5 of them left , brand new, hit me up and can list them for you on ebay.

Does anyone have another one of those receivers? I just got a Mitsubishi WS-73903 and I am in need of one so i can get high def.