Date: Tue, 27 Dec 2005 22:54:26 -0600 (CST)
Subject: radio in a penguin peppermints tin
X-UID: 115
Content-Type: IMAGE/JPEG; name="img2483.jpg"
Content-Type: IMAGE/JPEG; name="img2485.jpg"
Content-Type: IMAGE/JPEG; name="img2486.jpg"

The MaxStream radios fit inside a Penguin peppermints tin very well. The 
pink antistatic foam is re-used as a standoff from the bottom of the tin. 
Note that the new style peppermint tins with the holograms are slightly 
larger than the both the old style tins (no holograms) and the new style 
red cinnamon tins. The extra one to two millimeters is noticeable as the 
fit is tight.

I haven't fully tested the radio in the peppermint tin housing. But I 
don't believe I made any mistakes wiring it. The default command mode 
sequence of "+++" results in a reply of "OK".

30 gauge wire is ok as maximum current is 150 milliamps. This is only 
during transmission.

The GPS receiver doesn't require a housing as it is sealed and can be 
immersed in water. I only need to wire the end of it's cable with a RJ-45 
plug.

The matching pair of GPS and radio for the laptop will be the same except 
that there are additional components to handle RS-232 to 5 volt TTL level 
conversion and provide power. I'm thinking of drawing power from a USB 
port and so avoid the need for a battery pack and power switch. Maximum 
current should be 210 milliamps for the radio and GPS receiver combined. 
This is well under the specification of 500 milliamps per USB port. 
However, this does worry me as an electrical fault could cause damage to 
the laptop. Serial ports alone are relatively safe electrically by design.