Homebrew PCBs

Hi Ted,

I haven't done any layouts for HF.  Last time, I think it was probably a 
tube circuit.  Ok, maybe some simple single side circuit laid out with tape.

I went to your website, but couldn't find the SKN xcvr.

Although I did a few sample autoroutes on my board, I just "kept going" 
after getting the the pwr routed.  Wasn't that hard!  The board was 
fairly simple, 'tho.

And I came to appreciate why boards (digital anyway) are often routed 
one direction on top, and a cross direction on the bottom.  It keeps the 
paths open, and minimizes vias.

Alan  KM6VV

kilocycles wrote:
> Alan,
> Sometimes I have an idea of the layout beforehand, but sometimes I
> don't.  Generally, I'll put a voltage regulator circuit in a section
> of the board that minimizes the wire length to the switch on the
> panel, or to the dc socket on the back panel, however the circuit is
> configured.  Same for RF output; I'd prefer to have it at he back of
> the board.  In the case of this IF board, the input from the crystal
> filters comes in at the 3" wide left end of the board, because the
> switchable SSB/CW filters I'll be using will be on a sub-board.  They
> will be fed by the RF input filter/RF amp/mixer/post-mixer amp board,
> and obviously I want the input to that board near the back of the
> case, but it's not as critical, since it's simply an antenna
> connection through coax.  I'd like to try to minimize the number of
> wires and cables I have flying over the PC boards, though.
> 
> When I did the SKN Special trans-receiver, If you take a look at the
> web site, I printed out correct-reading images of the boards and glued
> them to cardboard, and did the final planning by shuffling them
> around.  I had to reposition the VFO compartment to the side under the
> top lip of the case after I modified the low pass filter to a better
> design that turned out to need more length.  I was watching "Rides"
> the other night, and they were converting Jay Leno's Toronado to rear
> wheel drive, and then "oops...we forgot the air conditioner...now
> where do we put that?"  It ended up in the trunk.  Sometimes planning
> will carry you only so far!
> 
> I did autorouting almost exclusively when I first started with Eagle.
>  The rat's nest simply looked impossible.  One thing I use a lot while
> routing, either auto or manual, is "show ground"...click eye icon and
> type gnd in the command line text box.  That helps in that I know
> which end of the component to focus on; i.e., the signal end, and
> whether or not I need to reorient it. The triangular
> emitter-base-collector transistors drive me batty, trying not to have
> to run a signal through the triangle.  The pad clearances are pretty
> close as it is on a TO-92.  Also, I'll use the "i" info icon to show
> what signal I'm dealing with, and check the schematic.
> 
> I aim to minimize the length of the signal paths whenever possible. 
> With autorouting, especially if you have it set on a less intelligent
> setting like 20, as opposed to 50, the signal paths may end up being 3
> or 4 abreast, running around the edge of the board.  That's annoying,
> when the components they are trying to connect are only 1 inch apart.
>  Often, you can reposition a couple of resistors to allow the track to
> run beneath one, bisecting it, and eliminate one signal running around
> the edge of the board.  It takes some juggling around.  The routing on
> the SKN Special receiver board became a whole lot simpler once I put
> in the multiple power connection points.  The tradeoff of much more
> sane RF paths vs. a few extra connections to the +12V jack was easy to
> make, in that case.
> 
> 73,
> Ted
> www.kx4om.com
>