From 3a1233682802299fde0d8d0dad4479fdf8e1fc7e Mon Sep 17 00:00:00 2001 From: Bdale Garbee Date: Wed, 13 Apr 2011 19:07:17 -0700 Subject: [PATCH] shave 50 mils off SMA end of PCB to allow for SMA flange to be inside box --- Notebook | 32 ++++++++++++++++++++++++++++++++ telebt.pcb | 14 ++++++-------- 2 files changed, 38 insertions(+), 8 deletions(-) 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! + diff --git a/telebt.pcb b/telebt.pcb index 81b57eb..0e965c1 100644 --- a/telebt.pcb +++ b/telebt.pcb @@ -1565,17 +1565,16 @@ Rat[169274 42907 1 192094 110098 1 ""] Rat[192094 110098 1 241801 119108 1 ""] Layer(1 "top") ( - Line[287402 133854 24606 133854 100 2000 "clearline,lock"] + Line[286338 24606 286338 133854 100 2000 "clearline,lock"] + Line[286338 133854 24606 133854 100 2000 "clearline,lock"] Line[24606 133854 24606 121063 100 2000 "clearline,lock"] Line[12795 109252 0 109252 100 2000 "clearline,lock"] Line[3927 0 266732 0 100 2000 "clearline,lock"] - Line[291339 24606 291339 129921 100 2000 "clearline,lock"] - Line[278543 24606 291339 24606 100 2000 "clearline,lock"] + Line[278543 24606 286338 24606 100 2000 "clearline,lock"] Line[266732 0 266732 12795 100 2000 "clearline,lock"] Line[0 109252 0 3937 100 2000 "clearline,lock"] Arc[3937 3937 3937 3937 100 2000 270 90 "clearline,lock"] Arc[278543 12795 11811 11811 100 2000 0 90 "clearline,lock"] - Arc[287402 129921 3937 3937 100 2000 90 90 "clearline,lock"] Arc[12795 121063 11811 11811 100 2000 180 90 "clearline,lock"] Polygon("clearpoly,lock") ( @@ -1589,16 +1588,15 @@ Layer(3 "outline") ( Line[3927 0 266732 0 1000 2000 "lock"] Line[266732 0 266732 12795 1000 2000 "lock"] - Line[278543 24606 291339 24606 1000 2000 "lock"] - Line[291339 24606 291339 129921 1000 2000 "lock"] - Line[287402 133854 24606 133854 1000 2000 "lock"] + Line[278543 24606 286338 24606 1000 2000 "lock"] + Line[286338 133854 24606 133854 1000 2000 "lock"] Line[24606 133854 24606 121063 1000 2000 "lock"] Line[12795 109252 0 109252 1000 2000 "lock"] Line[0 109252 0 3937 1000 2000 "lock"] Arc[3937 3937 3937 3937 1000 2000 270 90 "lock"] Arc[278543 12795 11811 11811 1000 2000 0 90 "lock"] - Arc[287402 129921 3937 3937 1000 2000 90 90 "lock"] Arc[12795 121063 11811 11811 1000 2000 180 90 "lock"] + Line[286338 24606 286338 133854 1000 2000 "lock"] ) Layer(4 "silk") ( -- 2.30.2