Hello, I hope to get help on here for a few specific questions. Please excuse my ignorance on some items as I am still educating myself when I can on Radio knowledge. I am the safety manager for a relatively new company which is a peanut sheller in a rural community (we have been in business for about 1.5 years and I have been here for right at 1 year). As part of the tasks given to me, I need to establish a functioning radio communication network and do it as inexpensively as possible. At the previous place I worked we had Motorola CP-200 radios but mainly they worked inside the building and were not used for a large distance.
First thing that pops into my mind is the possibility of dust from the processing. Do you need intrinsically safe radios? Using the wrong type of equipment in that environment can be very dangerous. I'd suggest finding a professional consultant. You don't want to be the guy who's responsible for someone getting killed.
When someone with little to no experience wants to do a radio system as "inexpensively as possible", it's always a red flag.
Radio systems need to be designed by professionals, especially when life safety is involved. This isn't something you do on the internet by buying cheap equipment off e-Bay/Amazon. That's a disaster in the making. You cannot put this together by buying parts. You need training, knowledge, experience and some very expensive test equipment to make everything work correctly and meet FCC requirements.
You'll save a lot of money by brining in a professional.
Background:
I have established a few things so for:
- FCC license for 5 frequencies in the UHF frequencies 400-470 MHz
- Purchased and programed (18) 5 watt FPCN30A Samcom radios
- Purchased (6) 10 watt H-6 Tidradio (have not programed yet as they just arrived)
- I also have 3 other radios: (2) Baofeng UV-5R and (1) Baofeng BF-F8HP (I used these as test radios to determine what to get)
Do you have the FCC license in hand?
FPCN30A Samcom - The specs on these radios is very poor. While they meet FCC requirements, the poor specs is going to create issues. Life safety should not depend on Cheap Chinese Radios.
H-6 Tidradio - These radios do not have FCC Part 90 type acceptance and cannot be legally used to transmit anywhere other than amateur radio bands.
Baofeng UV-5R - These are the poster child for "Cheap Chinese Radios".
Baofeng BF-F8HP - These radios do not have FCC Part 90 type acceptance and cannot be legally used to transmit anywhere other than amateur radio bands.
Facility and Layout:
The structure of our facility is made of metal and sits on about 60 acres on a relatively flat, but sloping plain. The warehouse feeding the plant has an underground tunnel surrounded by several feet of concrete. We also have some very tall grain(peanut) elevators. I recognize that the area covered should possibly have a repeater.
Problem:
The 5 watt radios cover most of the area from the front offices to the plant with out too much issue, however, once you get past the plant the radio signal drops to heavy static or nothing at all. The tunnel gets no radio reception at all.
Not surprising.
Not trying to bust your chops here, but we need to point out that you are using very, very low tier radios that are known to have very poor specifications. That's working against you.
There's the real possibility that interference from the machinery may be causing issues.
Trying to cover an underground tunnel takes some very specific designs, and it's not something that will be easy or cheap to do.
I got a quote on a repeater and it was
WAY MORE than my company is able/willing to put out at this time. So I have been tasked with getting done a difficult, but I don't think impossible, task. I have come across a device that I believe will work well enough as a repeater for our "little" area. (here is a link to it on amazon-
2 way repeater box). It consists of using 2 mobile radios linked by a box. We don't need a repeater that works for miles just enough to get a signal from the furthest corners of our property.
That repeater interface is going to be a hot mess:
-It does not supply what you need to meet FCC requirements. It needs to ID with your call sign. It needs to have settings that shut it down in a malfunction.
Putting two hand held radios side by side with that little box is going to result in desensitization of the receiver, and will more than likely lock up the system and make it totally useless. Wrong tool for the job.
So here is where I start asking the questions:
- When setting up a repeater, do the Tx and Rx frequencies both have to be from the FCC or is one frequency issued and then the user does an offset?
The FCC license needs to specifically list authorization for a repeater. You need to work with a frequency coordinator to find the proper frequencies to use. The FCC will license you for the repeater. You cannot just pick frequencies or offsets that are not licensed.
In addition to the device above, I would like to use external antennas to Rx and Tx. Can I link 2 receiving antennas with a splitter going back to the Rx radio? Likewise, can I link 2 transmitting antennas with a splitter? See 2 options below. Which is more feasible? I need to try to cover the tunnel and the yard area with the same repeater.
No. You need tuned duplexers to do what you want on the transmit side. On the receive side, it can work, but you need filtering and something to offset the losses from the splitter. This is where a trained professional can design an actual functional repeater system that will work. Building a repeater with junk of Amazon is going to lead to major disappointment and lost money. You'll spend a ton of money and labor trying to make this work the way you want. In the end, it's not going to work and you'll still end up paying a professional.
Does a duplexer have to be programed for the frequencies we have or can I program it myself if I need to order one? any suggestions on the best one to order?
Duplexers need to be tuned, and they need to be tuned on site. Having them tuned and then shipped results in them vibrating off the tuning and not working correctly. It needs to be done on site by someone with a service monitor ($40,000 piece of test equipment).
The correct duplexer to order is one that is specifically designed around your needs, loss budget, frequencies, power level, and installation location. Good ones start at $2,500. Cheap Chinese ones off Amazon still need to be tuned on site, and will have poor performance, especially if your repeater pairs are closely spaced. This is one place you do not want to cut corners.
I want to mount the antenna to the highest point which will be about 75'-100' off the ground What type of antenna should I get,
vertical or
Yagi? Something else?
It depends on what your coverage needs are. There is no "one" antenna that works in every application. This is another place where a trained/experience professional can choose the right antenna for the job.
The antenna gain/pattern will need to be based off what your FCC license allows. That's something that needs to involve the frequency coordinator and whoever designs this system for you. You cannot just grab an antenna and install whatever you want.
I am looking at running about 100' of cable maybe more. What type of cable should I run from the radio to the antenna? RG-58, RG-6, RG-8x?
For 100 feet, on UHF frequencies, for a repeater, with low power, you need to be running something like 1/2 inch Heliax or better.
Keep in mind I'm not looking at this as a long-term solution; I just need this to get by for now so that we can have communication for an emergency. Any help or ideas this community can contribute will be greatly appreciated!
Doesn't matter if it's long term or short term, for emergency or not, it needs to be done to FCC rules.
I can really, honestly, appreciate your enthusiasm and desire to save your employer money.
But, you're not the first guy to show up here with a plan like this.
Many of us do this stuff professionally.
Please take this with an open mind and as advice from those of us that do this for a living:
You are in WAY over your head.
This isn't going to work. You're going to spend a lot of money on junk radios and junk equipment, then a ton of labor on trying to make it work. It's not going to work. You'll either piss off your employer so bad they'll can you on the spot, or you'll end up calling in a professional and eating all that lost money and labor.
Really, please, you need to bring in a professional if this is the system you want to design.
Or, use cell phones. Or, use a WiFi network with WiFi radios.
This is not a playground that's cheap to play in. Any employer that wants to do this on a budget has no idea what they are doing. Doing it wrong is going to cost a lot of money, and you run the risk of the FCC knocking on your door.
We're happy to help, but please, understand what people are telling you. This isn't going to go the way you want.
