X-Git-Url: https://git.gag.com/?a=blobdiff_plain;f=Notebook;fp=Notebook;h=1b9250391473d22640746dfb9f57ddbbb809b068;hb=3a1233682802299fde0d8d0dad4479fdf8e1fc7e;hp=7deb6349bdc9ebe0d0ee33ed8d2ea7b4701354d5;hpb=0ccc17f392c76cb0bc8decbb64fab8c2ccba3cf4;p=hw%2Ftelebt

diff --git a/Notebook b/Notebook
index 7deb634..1b92503 100644
--- a/Notebook
+++ b/Notebook
@@ -39,3 +39,35 @@
 
   Rough estimate of cogs puts us at retail price of $150
 
+2011.04.13
+- Pondering how much to clip off the SMA end of the PCB to ensure the SMA
+  flange fits inside the box.  
+
+  Our connector needs 3.81 mm "above" the PCB which for TeleBT actually 
+  means between the PCB bottom surface and the base of the box.  The box 
+  boss height is specified as 4mm, so that fits in a purely vertical sense,
+  but I'm worried about the box wall to base radius, and the fact that the
+  box walls aren't exactly vertical.
+
+  Hammond doesn't specify the radius between the wall and base of the 1551K
+  box.  Given other things they do specify, it might be that 1 mm is a
+  conservative guess.  The specification for the inside dimensions of the lip
+  around the lid is 10 mils smaller than the max PCB dimensions, and it *looks*
+  like that inside edge might be about where the wall radius ends.  The drawing
+  shows the lid inside as 6.73mm less than box outside dimension, which seems
+  reasonably consistent with my estimate of a 2mm wall thickness, about 1mm
+  for the lid lip, and some mold tolerances.  So, let's use the box lid lip
+  inside dimensions as a proxy for the box base inside dimensions until proven
+  otherwise.
+
+  So we need to peel 5 mils off to account for the box radius.  The flange
+  itself is 40 mils.  And I'm nervous about the guesstimates so I'll add 
+  another 5 mils of margin.  So we need to take 50 mils off the SMA end of
+  the PCB.
+
+  As a sanity check, on TeleDongle the closes screw hole is 78 mils from the
+  SMA edge of the PCB, which is 50 mils less than a maximum-size PCB would
+  have.  If anything, the TeleDongle SMA ends up inside the wall a bit more
+  that necessary, such that tightening the SMA nut deflects the wall inward.
+  So, 50 mils might indeed be a good choice for TeleBT.  We'll give it a try!
+