# Best Way to Arm Altimeter

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#### edwardw

##### Well-Known Member
Hey all,

I have been wondering how you all arm your altimeters? I have a 3" mailing tube rocket for my L1/L2 certs coming up in March. I have the e-bay built and in the past have used a roller switch that is NO when depressed. I put a piece of brass tubing to guide a dowel and then remove it before flight. I think the perfectflite site has something on this already.

Any other easier methods to arm an altimeter? What do you all prefer?

Edward

#### Ryan S.

##### Well-Known Member
Twist the wires together. I would put a switch in my rockets but it gets complicated when you need to switch between rockets unless you put the switch in the board and reach through the vent hole.

I prefer just twisting the wires, it simple and easy

David

#### wyldbill

##### Well-Known Member
Originally posted by edwardw
How do you all hold your batteries in?
nylon zip ties through holes in the mounting plate. 2 radial, 1 axial per 9V.

-bill

#### edwardw

##### Well-Known Member
Well, for this rocket I just armed the altimeter by means of a remove before flight pin. I will post pics of the finished e-bay once I take them.

Edward

#### daveyfire

##### Piled Higher and Deeper
Originally posted by wyldbill
nylon zip ties through holes in the mounting plate. 2 radial, 1 axial per 9V.
I've gotten away in the past with 1 radial, 1 axial per 9v, even on 40g+ flights (J570W in a 54mm rocket and M2400 in 75mm rocket to name a few ) I then just solder wires directly to the contacts to avoid having the little 9v connector deelys short out. Have yet to have one fail!

#### AZ_Ron

##### Well-Known Member
Agree with the screw switches... I've NEVER seen Kevin or Marty's rockets NOT fire... I was twisting wires for years, because I was unhappy with every switch I'd tried, but Kevin showed me the screw switches, and they are what I have in my 2-stage, and that's what'll be installed in my 8" Red Max...

Ron