I am new to digital-era scanning. I grew up with a scanner on in my house 24/7, and I worked as a dispatcher for a couple of years after I graduated high school. I decided recently that I wanted to start monitoring my local police, fire, and EMS frequencies again (150 MHz DMR and 800 MHz P25 Phase I and II). I did my research and bought a Uniden SDS200, but I have problems receiving at my house. I’ve have tried the OEM rubber duckie antenna, the Remtronix REM-820S 800 MHz antenna, and the Diamond RH77CA 144/400 MHz antenna. I get about the same results from any of the three; I can/can’t receive certain frequencies depending on where I am located within my home or yard, even if I move a few inches. I can receive the 800 MHz P25 frequencies one minute, but not the 150 MHz. Then I move it to another spot and I can receive the 150 sites, but not the 800 P25s. I am pretty sure that I am a victim of topography. My house is in a low spot with 10-15 miles of hills and pine trees between me and the various broadcast sites that I am trying to monitor. I have decided to go ahead and setup a base station. I went ahead and bought an SDS100 to keep in the house, and now I am wanting to put up a mast-mounted antenna. I have an existing tv antenna mast that is 25-30 feet tall, maybe taller, and will require roughly 50 feet of coax. I have read and researched antennas, but I am just overwhelmed by the amount of information and the number of factors to consider. Could you guys please assist me in determining the right antenna for my situation?
Help me pick a base antenna for 150 MHz and 800 MHz on Uniden SDS200 due to Topography
- Thread starter downeydigs
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doctordialtone
Member
I use a Discone antenna. It is effective over a broad range of frequencies.
I have mine mounted on about 20 foot mast on the chimney. It works great and many others here have said the same.
D130NJ Diamond Super Discone Antenna | Scanner Master
D130NJ Diamond Super Discone Antenna
www.scannermaster.com
I bought mine about 20 years ago at Radio Shack.
prcguy
Member
A typical scanner Discone will work well for 150MHz but above about 500MHz they start to degrade because the radiation pattern shifts upwards above the horizon, so 800 reception will not be as good. If fed with good quality coax it should still work much better on 800MHz than anything you have used at ground level on the scanner and 150MHz range should be really good.
There are many to choose from starting under $40 shipped to well over $500. Here is an inexpensive one that works well and I would recommend LMR400 cable due to your 50ft run. TRAM(R) 1410 Tram(R) Scanner 25MHz-1,300MHz VHF/UHF Super Discone Base Antenna 727932014577 | eBay
There are many to choose from starting under $40 shipped to well over $500. Here is an inexpensive one that works well and I would recommend LMR400 cable due to your 50ft run. TRAM(R) 1410 Tram(R) Scanner 25MHz-1,300MHz VHF/UHF Super Discone Base Antenna 727932014577 | eBay
Is what you are trying to receive all come from the same direction?
I am in mountains and trees. I put a Larsen tri bander on a Ground plane mount and it works great. https://www.theantennafarm.com/catalog/tram-1465-1703
For the most part everything is generally west/southwest of me. The P25 systems nearest sites are in the same general direction as everything else, but they do have sites in every direction around me.
I use a Discone antenna.
D130NJ Diamond Super Discone Antenna | Scanner Master
D130NJ Diamond Super Discone Antennawww.scannermaster.com
I was looking at the Tram Discone but then the mobile antenna with ground plane option came up. What are the pros and cons of these two options, and which would be best and why? Just trying to understand which decision to make and why.
I asked this because often a directional antenna will receive better than an omni antenna, if your signal source is from one direction, but if not then you need an omni antenna. If the signals you want are from the same direction perhaps two yagi antennas, one each tuned for the frequency you want, then combine the signal with a Diplexer might work well. I'm not an expert on this and I've never personally tried it, so someone please correct me if I'm wrong on that.
Many speak very highly of this antenna as an alternative to a discone,
OmniX Scanner Base Antenna
Specs Gain: 3 VHF 4 UHF dBi Pattern: Omni-directional Wavelength: 1/2 Elements: 3 Tuned: 118-137, 148-175 & 225-900 MHz Band: UHF & VHF Connector: N Female Cable: RG8X Cable Length: 16 Inches Height: 45" Width: 30" Weight: 2 lb Features Multi Band-Wide Coverage: The uniquely...
dpdproductions.com
Make sure you don't go cheap on your coax, at 50 Ft. at least use LMR-400, if you can afford it, maybe even larger, signal loss is pretty severe at 800MHz.
I like the set up I mentioned not only because it works well, but light weight so you can get it up high easily.
prcguy
Member
A scanner type Discone will receive all signals from a little over 100MHz to about 500Mhz equally well and similar in gain to a 1/4 wave ground plane, then it will degrade some as you go higher in frequency. A mobile antenna with ground plane can work better than a Discone if its a gain type but it will only do that over a very narrow frequency range. If you only wanted 150MHz and 800Mhz and will never ever venture into the VHF or UHF air bands, etc, then an appropriate mobile antenna with ground plane might suit you better.
If you choose a narrow band antenna now you can always swap it out for a Discone later if your listening habits change in the future. Or if you know that a Discone will work fine at your location for your 800 stuff then you can go with a Discone now and be done.
If you choose a narrow band antenna now you can always swap it out for a Discone later if your listening habits change in the future. Or if you know that a Discone will work fine at your location for your 800 stuff then you can go with a Discone now and be done.
The Larson Tri-Bander is 150, 450 and 800 and works well.
prcguy
Member
The Larsen Tri-band is 1/4 wave on each band and probably has a little loss on 150 due to the trap coil thing. It will also only work well on the specific narrow frequency ranges its designed for. If you buy a new one with ground plane kit it will probably run $75 on up where an OK Discone can be had for under $40 with shipping.
Here's a SWR plot of the Tram 1410 discone vs a Tram dual-band mag-mount:
The mag mount does better than the discone in a couple of places where it is resonant, but overall the discone is far better. In the 450-475MHz range the dual-band is significantly better, but most everywhere else, the discone is as good or better.
The mag mount does better than the discone in a couple of places where it is resonant, but overall the discone is far better. In the 450-475MHz range the dual-band is significantly better, but most everywhere else, the discone is as good or better.
Ubbe
Member
The tribander looks to be a bit off frequency in the 800MHz band? It goes from 700-750Mhz but not 850MHz.
But it probably will be difficult to adjust as the 180MHz and 500MHz would then totally go off their frequency bands.
/Ubbe
But it probably will be difficult to adjust as the 180MHz and 500MHz would then totally go off their frequency bands.
/Ubbe
If you're referring to my plot, it's only advertised as a dual-band antenna--VHF and UHF.
https://www.theantennafarm.com/catalog/larsen-nmo150-450-800-1050 I think my post was pretty clear. Just for once can you guy's not try to overthink everything.
Pointing out that a multi-band whip is only good at a few relatively narrow frequency ranges isn't "overthinking" anything. That's fine if you never venture outside those ranges, but if you do, a discone is a better option.
prcguy
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