I think you should let the tech write it down and put it in a sealed envelope. Keep it to yourself. Dont open it until you are prepared emotionally and mentally.
Also, if it is the gender you want how can you keep that excitement to yourself? how would you tell your DH that you did find out? Maybe you can say the tech accidentally told you? I think it would be so hard to keep it a secret.
And if it is the gender you dont want to hear... I think it would be hard to keep that a secret as well. I think you need some support. I have my sister she knew exactly how I felt and how I was brainwashing myself to want a second girl. And it was nice to rant and talk to her everyday and plus this website has been fantastic. BUT if you read it's a boy... prepare yourself. Make sure you are ready to open the envelope and realize you may one day have to tell your DH your found out. Whether it is blaming the tech OR telling him you found out.
I did contemplate finding out without my DH knowing even had my sister helping me figure out a way to find out without DH just incase it was another girl. BUT I realized this is just as much his baby as it is mine. He is just as much involved and wanted this baby just as much as I did and even though I am making and creating and carrying this baby... his heart is in it 110% and I couldnt do that to him. I wanted to find out in a special way together OR not at all and keep both of us in the dark.
Good luck! I hope you hear GIRL!