Preplanning antenna setup for multiple radios/antennas

[vdubb16]

I recently became a feed provider for county i live in. im only running a RS scanner with the original antenna mounted high in the garage. but i listen to many frequencies for many agencies in 2 different counties that its nearly impossible to keep track of whats going on. and im only 20 miles from another county line out on coastal flatland so i may add even more.

im going to pick up a couple used vhf mobiles cheap to use to improve my feed.
So the setup i want will be something along the lines of the below listed.

Im looking for suggestions on antenna recommendations/ configurations for a base setup. Top of the house is appx 13 ft from the ground. with no over head lines to be concerned with. Immediate area trees no more than 20ft tall id guesstimate.

VHF Mobile- Carteret County Fire/EMS/Sherriff/Local PD- 30 mile Max
VHF Mobile- Craven County Fire/EMS/Sherriff/Local PD's 70 Mile Max N/NW
RS Scanner- UHF MCAS Military Police/Fire/EMS Occasional VHF Marine 13 Miles
CB Base Station- Imax2000
800 Device and antenna???

workin on figuring out City of New Bern Fire/EMS/LE "craven county NC" and NC Highway Patrol. Newberns TRS and HP is low band to go VIPER soon i believe. Ill add a device to accomidate in time.

Also I do not intend to broadcast the MCAS frequencies, if im not mistaken thats prohibited by RR..i work in dispatch so i listen in on what s*** im walking into when i get ready to go to work at night.

 

[ka3jjz]

I don't deal much with CB, so I'm not going to comment there - however, for all of your VHF/UHF stuff, I'd consider an Omni X from DPD or a good discone into an Electroline multicoupler (if you have too much loss, a Stridsburg is a possibility - but they aren't cheap...) . For 800, I'm unsure as to which of the current crop of trunktrackers works best with VIPER (go ask in the NC forum) but clearly a nice small 800 beam (so you can point to the tower(s) that work best in your area) would be a good investment. Those things are quite tiny, inexpensive and you wouldn't need much of a rotor to turn it if needed.

LMR cabling and appropriate grounding/lightning protection is a given

73 Mike

 

[Captain_Nojaa]

Im looking for suggestions on antenna recommendations/ configurations for a base setup. Top of the house is appx 13 ft from the ground. with no over head lines to be concerned with. Immediate area trees no more than 20ft tall id guesstimate.

VHF Mobile- Carteret County Fire/EMS/Sherriff/Local PD- 30 mile Max
VHF Mobile- Craven County Fire/EMS/Sherriff/Local PD's 70 Mile Max N/NW
RS Scanner- UHF MCAS Military Police/Fire/EMS Occasional VHF Marine 13 Miles
CB Base Station- Imax2000
800 Device and antenna???

If you're looking to cover multiple services in multiple bands, I suggest having a radio/antenna combination for each band. I don't know what range you're looking to cover, but your best bet is to get an antenna cut to the center of the band you want to receive; that would cover the most amount of frequencies and be more resonant than a wide-band antenna. Of course, any antenna will receive RF, but if the antenna is cut for the frequency range you want, it will be much more resonant to those frequencies. Also, you want to get your antenna as high as possible. The higher the antenna, the better your reception. A good calculator for determining antenna length is available at Antenna Length Calculation .

You stated you have some trees around your house. Try to keep your antennas as far away from the trees as possible. Trees have a tendency to block or attenuate signals at certain frequencies; any metal buildings, if in the path of the antenna, will tend to reflect signals which might result in multi-path distortion.

Another thing to consider is your scanner. Scanners will scan through the channels faster if they are programmed sequentially. Even with today's lightning-fast scanners, there can still be a slight delay if the channels are programmed all over the place.

Make sure your masts are guyed if they extend a significant height above your house. You can't listen to your scanner if your antenna falls down or the wind blows it over!

You mentioned CB -- if you are going to setup a CB transceiver, it would be a good idea to install high-pass filters on all your scanner antennas. You can get filters that are tuned to allow the range of frequencies at and above the filter's design frequency while blocking all signals below that frequency. Many electronics firms can sell you a custom-made filter, or if you wish, you can make your own from plans that are readily available on the Internet.

Finally, and perhaps most important -- make sure your masts are properly grounded! Use a copper grounding rod about 8 feet long, and drive it into the ground until only a couple of inches of the rod are showing above ground. Use a heavy copper cable or grounding braid to attach the mast to the grounding rod. If your masts are within close proximity to each other (no more than a couple feet) you can connect them to the same grounding rod; otherwise you will need a separate rod for each mast.

Also of equal importance -- you will also need to have some method of disconnecting your antennas from your scanners when thunderstorms move into your area. A knife switch with one side connected to the scanner and the other side connected to earth ground is a good system. if that isn't possible, then make sure your coax connectors or wire ends are easily accessible so you can disconnect them quickly when necessary. And power your scanners from a power strip or bar that utilizes both a lightning arrester AND a surge protector, but in any case, disconnect the power from your radios during a storm. If you can find an isolation transformer into which you can plug the power strip, that will be even better. The transformer will isolate the line from your radios give you additional protection from surges and spikes. The transformer will also greatly attenuate or eliminate any line noise that could creep into your equipment and cause a false signal to lock-up your scanner.

I hope this will help you in the setup of your radio shack.


73 de NØJAA

 

[vdubb16]

good info guys, thank you.

id imagine that it would vary based on the antennas, but what are the effects of the antennas on one another being close in proximity.

the filter for cb frequencies is a good idea.

ive got 2 sticks of 12 ft 1 7/8 exhaust pipe layin at the house. Bury lets say 2 feet down with a bag on concrete. They would join together just below the roof so if need be it would be easy to take down the antenna for whatever reason. And by "guyed" im assuming you mean supported elsewhere up the mast. i have not put much thought into it but i figure i could use a hole saw into say a 2x8 and attach at the roofline to the bottem of the garage trusses. have the mast come straight up through the hole.

Thoughts?