If you are searching for Satellite, you have one of a couple of issues
1) Your dish is not aimed correctly
2) you have a bad coax cable running from the dish to the receiver
3) you have a bad reciever
If you were having a prolem with the access card in the reciever, you would receive a message informing you to install the correct access card.
While you can not just MOVE the access card between units, you can call D* and they will sell you a card for $20 and if you get the right CSR and have been a good customer, they will waive the $20. It never hurts to ask.
There is nothing wrong with you having a second receiver on your account at your cabin as long as your don't not occupy the cabin on a regular basis, D* has no problem with it. I have beenw ith D* for over 10 years and they know we have vacation property and have a receiver there and it is mirrored on to my primary residence account.
If all you want to do is move your access card between the receivers then what you need to do is call D* when you get to your cabin and inform them youa re at your cabin and need to reauthorize the access card for that receiver. When you get back home, call them again and they set everything back.
I know quite a few people who do this very thing and D* has no problem provided you keep them in the loop. My parents for a good example snowbird between California and Northern Minnesota (here in N. MN for 3 months a year) and all they do is take their access card from their receiver in CA. and bring it with them to their cabin. When they arrive, they call D* and they reauthorize the card and change their locals to Duluth. When they arrive back in California, they call D* and they reauthorize the card for that receiver and give them LA locals.
My first suggestion is figure out what is wrong with your signal. Chances are good your dish may have moved just a enough to lose the signal or you have a bad run. After you have fixed that, Call D* and ask about getting a dedicated access card for that receiver. If they won't give you the access card for free ask them if there is any promotions they will offer you right now. You might be surprised they might offer you something like FREE HBO or Showtime for 6 months which will make up for the $20 you had to pay for the card..