Batboard

Can I use the Mini-Circuits ZB6PD1-900 "power splitter/combiner" to feed three 800mHz scanner / Rx only radios. Is that its actual purpose?

1in/6out means about 8db loss (?), so is it possible to build a power amplifier using something like the Maxim 2056 chip before the input of the splitter?

Or should I forgo all this and just get three separate antennas installed? Because I would have a GPS and a UHF antenna as well for the two-way radio, I'd rather not have an antenna farm. The fewer the better.

Mini-Circuits data: http://www.minicircuits.com/ZB6PD1-900.pdf

Maxim 2056 chip data: http://www.maxim-ic.com/quick_view2.cfm/qv_pk/4604

Reason I'm asking is that I may be getting a new vehicle from work in the next several months (news photographer) and the installer that we use aren't exactly known for their stellar work. Just pre-planning, I want to put as much detail of what I want done, short of installing it for them.

Cool - I do freelance photography myself for several stations/networks.

Yes, a power splitter (aka power divider) can be used in this application, as long as the radios are definitely not transmitters. If one ever transmits, it's likely to fry the other radios (power is divided out every port... send 45 watts in any port and it'll come out the others).

Theoretical loss per number of ports in dB:
2 - 3dB
3 - ~4.7dB
4 - 6dB
5 - ~7dB
6 - ~7.8dB
8 - 9dB

Actual loss per port will be slightly higher (the table above assumes ideal, thus impossible, circumstances.)

For a power amp, I'd look into Advanced Receiver Research (http://www.advancedreceiver.com). Good prices, and they sell finished out amps, rather than having to build your own.

The more expensive way to go is to look into a "receiver multicoupler", which has both the power divider and the preamp integrated, but those, from companies like RFS/Celwave, get pricey (think $500-$1K+).

Bear in mind that doing this will make the incoming antenna feed quite frequency-specific. For instance, lots of people run 3dB-gain 800MHz antennas on scanners, as they tend to work great on VHF and 800 and OK on UHF. However, that configuration won't work through a power divider and preamp, as the components will cause quite a bit of out-of-band loss.

I've got 18 on the roof, so I just run a separate antenna to every radio. Of course, with my FD involvement, most of the radios are TX-capable.

Thanks!

... everything that I need to listen to is in 857-870, so the more specific the better! Unless I can find a filter too. A few VHF things are on my handheld scanner... that's about it.

You might consider tossing a bandpass filter into the mix, then, just to get rid of the out-of-band garbage. If you're using scanners and not real radios, this will help get rid of most of the pager intermod on the 930 band.