As it sets, it is perfectly good for an HT on high power or a mobile on low to medium power. Using a relay for anything else is acceptable provided normal spike prevention techniques are used. You could probably save some money by replacing the VN920 with a part that more reasonably meets the trace capacity.
Speaking of the manual, you might want to add the current carrying capacity for those pads. Here is the calculator link again. Since this is a 2 layer board, use the second table for "External Layers in Air". http://circuitcalculator.com/wordpress/2006/01/31/pcb-trace-width-calculator/ I will note that the trace length is only used in the calculation for IR drop and not in the trace width. The calculations match what my PCB sofware spits out through simulation. Larry K7YBZ --- In [email protected], Scott Miller <sc...@...> wrote: > > On the Proto C the traces were both top and bottom. But with the > production version, it's an SMT part and I don't think I can make the > traces much larger. You can always solder some copper wire straight to > the VN920 leads if you want more current carrying capacity. > > Scott > > k7ybz wrote: > > > > > > Scott, > > > > I thought those traces were wider. I ran the values through the PCB > > calculator and it came out to 6.4 A for a 20 degree C rise at 25 degree > > C room temp. A more reasonable 15 degree C rise gave 5.6A for the 100 > > mil trace width. > > > > For 10A the trace width would need to be 230 mils and 20A would be 580 > > mils asuming a 15 degree C rise. > > > > Larry > > K7YBZ > > > > > The VN920 is rated at 30 amps. The traces are 100 mils wide, 1 oz > > > copper, and maybe 1/2 inch long. It's mostly a matter of how much > > > temperature rise you can tolerate in the traces, so it's going to depend > > > on the duty cycle. > > > > > > Scott > > > > >
