I have read (here) that the dual tuner receivers nag you if you unhook the phone line.
If you pay the extra $5/month, they don't nag you.
See other threads for more info on the subject. (and try for yourself)
The reason I suggested taking one of your existing receivers with you and NOT having a whole spare receiver around, is the following...
For Dish to be happy with you having a 5th tuner, it has to hook up to the home LNB some way.
Since you didn't describe how your current LNB (and possible switch) are configured, it's quite possible that they have a limit of four tuners.
So, adding a fifth, could be a major problem, when all you really want is to take one receiver away occasionally.
What would be ideal, is if you had two 301/311 receivers instead of the 322.
But of course, you'd be paying the extra $5 for the second one, and you (probably) don't for the 2nd tuner of the 322.
So, call up Dish, and complain (if true) that you have a "Plug in the phone line" message on your display, and that the line is bad in the walls.
Tell them you'll pay the extra $5 and to fix the problem. They can do so on the spot.
Now, any time you want to pull out the 322 and take it with you, you're good to go.
Yes, you can aim the Dish 500 at just 119, if you like, and get it to work.
I haven't found it difficult to dial in the proper skew and get both birds, even when testing on a pole in the back yard.
Others will point out that you'll have the TV display handy when you are aiming and no other equipment is needed, but I insist on a $20 satellite tuning meter for quick setup.
I even have a proceedure using two meters for dialing in both birds at once, but the single meter gets the job done.
Try it, and after experimenting a few times, you will be good at it.
Last year, I helped a friend do a self-install at his house.
After his second or third attempt, he had a better set of signals than I had at
my house!
If you insist, you could use a surplus DirecTV (or Dish) single LNB antenna.
Problem is, it'll most likely be legacy, not DishPro (which I assume you have at home), so the receiver will need some fiddling with the
Switch Check feature, whenever you go mobile.
fine print:
To finish up, and I didn't want to have to say this, but just to put any future questions to rest...
Do
NOT expect to use one of the 4000 receivers you have laying around.
Even if Dish would reactivate one, they're Legacy only, and won't play at all with what is undoubtedly DishPro or DishProPlus LNB and switch in the house!