VHF Preselector

[willawake]

I have this preselector which i will use for optimising (hopefully) my reception of marine AIS signals which are on channels 161.975 MHz and 162.025 MHz. So this unit is peak tuned to 162 MHz.

The manual says it needs 10-15 Vdc and has current drain 10 mA.

So it says to solder postive wire to E1 which is ok. and the ground to the ground plane on the pcb.

where is that?

secondly it is apparently best to have this at the antenna (which in my case is 30m up). So any ideas for power? i guess some kind of battery, preferably not having to change/charge it too often. and umm taking into consideration that it will toast in the summer sun.

[kikkoman]

Re: VHF Preselector

Ground is the large copper plane on the backside. You can also solder to the shielding of the cinch connector (doesn't matter which one, but preferrably the output) or one of the mounting screws, in case you mount the borad on a chassis and use metal screws and metal washers.

10mA isn't that much - you could use a small solar panel. If the unit is sensitive to voltage fluctuations (clouds, sun etc) you can go the safe way and use a panel with a higher voltage - e.g. 20V nominal - and add a linear regulator.
a boost converter would be easier, of course, but they usually produce ripple, which might be bad in this case.
add a small R/C 12v lead battery in parallel, and you're done. if you adjust the regulator properly, you won't even need a charging circuit.

[willawake]

Re: VHF Preselector

thanks. i was thinking about solar.

[Harvey]

Re: VHF Preselector

I'm surprised its not designed to have power up the coax feeder...

[willawake]

Re: VHF Preselector

unfortunately its not recommended as will affect rf performance

[stretch0069]

Re: VHF Preselector

yeah....i'd have to suggest the solar panel route as well. not sure how much sun you get there, but like kikkoman suggested....if there are a lot of cloudy days, get a bigger panel. bigger is always better, right???

will's gonna suffer from panel envy now.

[willawake]

Re: VHF Preselector

not to worry. i have a big antenna mast.

solar is a bit expensive though i see (well, considering the premade kits) but yeah i would be interested to get into that also.

range is very dependent on weather, in bad weather it can be quite bad only 30 nautical miles. i dont know if a preamp will have much effect in those conditions so it probably doesnt matter if it is off (solar not working) antenna will still work even if the preselector is unpowered.

i really enjoy this stuff but pity nobody else in my area wants to join in.

[999999999]

Re: VHF Preselector

Solar cell or not you probably need a battery as a solar cell can't be relied on in extreme weather, darkness, etc. Put a SLA 12V battery down inside and run a lead up to this. Then you can decide how you want to go about recharging the battery- manually, trickle charger from another power source, or with solar cells.

Put some capacitance near the board, maybe a small ~ 10+uF 35V tantalum cap on the board at the power input. You could drill a hole where I show the X to hit the ground plane then + goes to adjacent hole diagonally to the left. You might need more, 30m is a fairly long run. Stay with solid caps due to weather, temp extremes.