kieronriley
Well-Known Member
se them for sale in force four chandlery cat.not so expensive but what is inside such a small componenent and could i make my own Kieron
v.h.f/a.m f.m splitter
- Thread starter kieronriley
- Start date
brianrunyard
Well-Known Member
There have been lots of threads on these in the past.
Personally I'd never introduce anything into the antenna system that's not necessary. It's sods law that it'll cause you a problem when you need your VHF the most.
For an am/fm radio you can usually get away with a length of wire hidden in the headlining unless it's a steel boat.
Personally I'd never introduce anything into the antenna system that's not necessary. It's sods law that it'll cause you a problem when you need your VHF the most.
For an am/fm radio you can usually get away with a length of wire hidden in the headlining unless it's a steel boat.
fluffc
Well-Known Member
They are little more than a junction in a metal tube. But very accurately made, to maintain impedance matching and avoid RF reflections.
So, no, it is not possible to make one yourself - unless you have access to some CNC equipment...
So, no, it is not possible to make one yourself - unless you have access to some CNC equipment...
MarkGrubb
Well-Known Member
I think you could make your own, but it may end up costing more than buying. One can probably be made using switching diodes and impedance matching. I'm speculating here, but the diodes would probably have to be arranged so the transmit power from your VHF doesn't blow up your radio, but both sets can use the antenna. You'll need the right diodes for this sort of application, probably PINs. As the previous message suggested, you'll need some impedance matching, but this can be done wth Capacitors, Resistors, and Inductors. If you know how to use a Smith chart or have access to CAD software that will help design the match. It's important to get things well matched to reduce loss. The whole lot can be built on a PCB to make it robust and low loss with impedance controlled tracks. Eagle is a good PCB design package and available for downloade free. There are plenty of companies that will make the board if you supply the gerbers. You could use veroboard of course, but you may find it more lossy at VHF. For marine applications you want something nice and robust, so a proper PCB is worth the effort.
st599
Well-Known Member
The impedance match into the antenna terminal would need to be very wide band so matching with LC would be "interesting".
And Eagle is great at PCB layout but sucks at Transmission line layout. Try TXLine to give you the dimensions prior to going anywhere near Eagle.
And Eagle is great at PCB layout but sucks at Transmission line layout. Try TXLine to give you the dimensions prior to going anywhere near Eagle.