Scanner splitter or diplexer?

[drdeputy]

In this case, RG 400 jumpers would fit the bill.

Are you saying short-run LMR 400 jumpers (6') or less, BNC male to male? I don't think I can make the turn into my scanners using LMR 400 without straining the radio's BNC female connector. Maybe it's just my setup, but bringing LMR 400 to the Stridsberg and then a different coax type to the scanners works better for me. I realize there is some loss in those last few feet, but it seems safer.

 

[ems55]

Do not use RG59. First of all, that's 75 ohm coax and you will have a tough time finding the correct connectors to go from BNC on the multi-coupler to BNC on the scanners (yes, 75 ohm BNC connectors exist for video application, but not ideal for 50 ohm RF applications). If anything, that should be RG58 which is matched 50 ohm coax. RG58 is not the best choice either, however.

I prefer LMR-195 or LMR-200 for short jumpers. High quality cable and flexible enough to go from the multi-coupler to the scanners. Should be very easy to find the lengths you need with BNC connectors on both ends. Keep those jumpers as short as possible and you'll be in good shape.

Who would you recommend for the jumpers ?? I have used CableExperts for my needs like various lengths of LMR400 WITH PL259 or N connectors. Good cable, service v& price !!
73 Michael WA1UZO

 

[Rawkee1]

LMR400 is to rigid for me. I need jumpers from signal splitter to the radios. I’m looking for 3’ to 4’ jumpers. What should I use and where can I get these jumpers with F connectors? I would use like LMR 200 or I think LMR 195, but I can’t find these short cables set up with the ends I want.

 

[MTScannerNut]

I don't use anything less than LMR-240 for jumpers, just my preference. I find it flexible enough, but you can always get LMR-240 Ultra Flex which is stranded center wire if you need max flexibility. You can buy assembled cables with whatever choice of connectors you need from several reputable dealers on eBay. I've used this seller several times with never a problem: LMR-240 Cables

Depending on the length you need, they are $15-$20. This is for genuine Times Microwave cable, not the Chinese junk. Contact them if you don't see the connectors you need.

 

[lu81fitter]

I can’t find these short cables set up with the ends I want.

The antenna farm. Here -----> Coaxial Cable | The Antenna Farm

I have bought numerous things from them. Good customer service as well. You can order custom cables with the ends already attached. Check it out.

 

[Rawkee1]

Thanks guys. I never thought about the cables from eBay. The antenna farm I dealt with before and they are very reputable. I was going to buy the cable itself but it’s a lot different than using the compression fittings I’m used of using for cable tv. Buying them made up is the way for me now!

 

[vagrant]

@drdeputy - RG-400 was mentioned as coax for a jumper. Do Not confuse it with LMR-400 as they are different.

 

[Rawkee1]

Your absolutely right vagrant, they are totally different! I am looking for a diplexer with so239 inputs to receive under 500mhz. Any thoughts?

 

[kj4jaq]

LMR400 is to rigid for me. I need jumpers from signal splitter to the radios. I’m looking for 3’ to 4’ jumpers. What should I use and where can I get these jumpers with F connectors? I would use like LMR 200 or I think LMR 195, but I can’t find these short cables set up with the ends I want.

I do realize you intend to use something less rigid than LMR400 for your jumpers/pigtails from signal splitter to radios. F connectors are 75ohm. LMR400 comes in 50ohm and 75ohm versions. I would not recommend using 75ohm connectors of any sort for a radio antenna setup as they (radios) are typically 50ohm. You mentioned SO239 inputs in a later post, which are UHF/PL259 connectors required for the cable.

In regards to the 500MHz and under diplexer, that is fine as long as you dont expect to have ideal splitting from anything above 500MHz. I personally would go with a higher frequency active version (and use N-connectors). This would also allow you to make your main feed/jumpers up with much easier to utilize connectors.

 

[vagrant]

Comet makes various diplexers that work well enough with low insertion loss. They call them duplexers, but disregard that. I am not sure of where you want the split, but they have different versions with different connectors.

Duplexers | Comet Antenna

wireless mobile and fixed station voice and data

cometantenna.com

Your absolutely right vagrant, they are totally different! I am looking for a diplexer with so239 inputs to receive under 500mhz. Any thoughts?

 

[Rawkee1]

Good point, the F connectors are 75 ohm. I plan on splitting the signal about 5" from the radios. The main feed will be LMR400

 

[sallen07]

Your absolutely right vagrant, they are totally different! I am looking for a diplexer with so239 inputs to receive under 500mhz. Any thoughts?

Is this still your original question? Or is this something different? If you are looking for something to split the signal from a single antenna so it feeds two (or more) scanners, then a diplexer is probably not what you want. A diplexer splits the signal by frequency, so one scanner would get (for example) 1.3-170 MHz, and the other would get 350-540 MHz. Is that really what you want?

 

[vagrant]

I think you're right sallen07. I presume Rawkee1 knew what I meant about the split, but then he noted the split "distance" from the radios.

Rawkee1, and anyone else who wants to learn more, I encourage you to read up on the following to discern the difference between a diplexer, duplexer and a multicoupler. I now believe you want to use a multicoupler, but sometimes people use a diplexer to attenuate a frequency range to a particular receiver.

Is this still your original question? Or is this something different? If you are looking for something to split the signal from a single antenna so it feeds two (or more) scanners, then a diplexer is probably not what you want. A diplexer splits the signal by frequency, so one scanner would get (for example) 1.3-170 MHz, and the other would get 350-540 MHz. Is that really what you want?

 

[Rawkee1]

I am trying to do my homework. It's much more involved now than it used to be. I bounced back in the monitoring scene about 5 years ago. Way back when, the 800's wasn't even a thought. I started with multi monitors with crystals until radios like the Pro 2006 came in. So you'll have to forgive me a bit when it comes to duplexers, diplexers, and multicouplers along with the vast array coax cables. I'll clear things up. I have two different outside antennas not near each other. The coax come in from two opposite ends of the house. The coaxes meet near the radios. I have two lines to combine at that point. 475Mhz is the highest frequency in concern. One antenna is a Discone multi band and the other is a VHF antenna. I just want to have the radios get the best of both worlds. I guess I could reprogram the radios so one would get just VHF and the other would get UHF & 800 but that is not what I really want to do. I get the 800's no problem at all because I'm near the repeaters. So the 800's really don't come into play.

 

[vagrant]

Okay, you need to do some testing/thinking. I am unsure what spread your VHF antenna covers, but you may goof yourself if that VHF antenna works best around 160 MHz and you are also interested in 118 MHz for aircraft. I am not saying your VHF antenna would not work to RX around 118 MHz, but the discone may offer improved performance there.

What I would do options:
1. Use the shortest coaxial run and put the discone antenna there. LMR-400 is a safe choice, especially for long runs. Then use a multicoupler.
2. Use one antenna for each scanner. Why? By having fewer frequencies on each scanner, your chances improve for hearing traffic. Also, if the 800 MHz signals are that strong, your VHF antenna may pick them up fine.
3. Use a diplexer to combine the antennas into one line and then also purchase a multicoupler to share the signals. As you can figure out, this option costs more and may not offer a benefit.

Although my needs are different, I actually use something like option #2 myself.

 

[kj4jaq]

I was going to just say option 3. But, I also agree to option 2 as well (also using LMR400).

 

[Rawkee1]

Thanks very much vagrant for your recommendation. I do know every time you split, combine, ect the coax, you do create loss. The best and strongest signals would be if I just use one antenna for each scanner with no splitting or combining. I will have to put some time aside to reprogram the radios to satisfy that option. Does anyone know if there is a coax between LMR240 and LMR400?

 

[Rawkee1]

Yes, option 2 I think is best and more cost efficient for the project I have on hand.

 

[kj4jaq]

There is an LMR-300 50ohm cable. I have never had my hands on it. I only use/keep spools of LMR400.

 

[Ubbe]

If you go cheaper than LMR400 then you can as well use RG6. If you have 50ft runs to each antenna then you'll have 2,5dB loss at 450Mhz using LMR400 and 4dB using RG6. There's a considerable cost saving going RG6 and there's only a 1,5dB difference in signal, even less on shorter runs. Going cheaper than LMR400 will gain you nothing in comparison to RG6.

/Ubbe