diplexer question

Subject: diplexer question 2009-05-20, 14:23

Is it worth using one? Or would it be best to use 2 box's with seperate dedicated antennae? (1 VHF..1 UHF )

any idea's would be welcome...

Location : various

Skoshi wrote:: Is it worth using one? Or would it be best to use 2 box's with seperate dedicated antennae? (1 VHF..1 UHF )

any idea's would be welcome...

Can of worms time ;)

What exactly are you trying to acomplish?

Two scanners with one aerial - multicoupler
Two or more aerials at different frequencies to one scanner - diplexer
Two or more aerials at different frequencies to one scanner - splitter/combiner

Usually a combination of the above....

First case - multipcoupler...fine, get a good quality one (Stridsberg are good but expensive). Inputs are isolated and you have a choice to have limited amplification (to overcome the insertion loss) if need be (this will add to the cost of course).
Second case - diplexer...the point of a diplexer is that it has frequency isolation and band-pass filtering. It is not a good solution for wide-band use (and airband monitoring IS wideband use). There are no units available off the shelf that would suit any sensible airband monitoring. Use a wideband aerial to start with.
Third case - splitter/combiner...generally I'd say don't even think about it. All sorts of wierd phase distortion and very unpredictable results. They have limited applications in analogue TV systems where there is a huge difference between the very limited frequency range of the desired signals versus the other received noise.

Of course I do always suggest people experiment as that is part of the fun of radio ;)

Subject: Re: diplexer question 2009-05-21, 11:07

can of worms indeed....

was intending on using this one...DIP2002-AB 118- 138Mhz 225 - 400Mhz ( http://www.ssejim.co.uk/37-dip2002ab.htm ) which seems to be ideal..

Along with the Amag 128 and 300A...on a Bearcat 8000 (or something else as i want another base unit but cant make my mind up yet)
http://www.ssejim.co.uk/27-mobileants.htm

i'll bow to your better judgement though dervish as you are way more knowledgeable in these matters...

Clap