Weak Viper Signal

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FW2518

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I have a Uniden Home Patrol 1 that I want to use at a home location to monitor our local EMS traffic. I have a very weak signal where I live. I have put up an external antenna and it helped a lot but I think I am still missing a lot. Will a directional external antenna help ? Can anyone recommend on to try ?
 

mmckenna

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Answer: Maybe.

It's difficult to know for sure without knowing a lot more about the specifics:
Where are you located?
Where is the closest tower?
What makes you think you are missing traffic?
How high is your antenna?
What type of antenna?
What type of coax?
How long is the coax?
What is your skill level with doing antenna installs?

Most importantly, what is your budget?

A directional antenna -might- help, but there are a lot of variables involved. It's impossible to make a blanket statement without knowing a lot more information.
 

FW2518

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I live in eastern Pamlico County. I not sure of the make and model of the antenna I am using. The antenna is mounted 20' in the air. I'm about 8 miles from the tower. The coax is rg58u 20 awg cable with with a MFJ-270 Lightning/Surge protector in the line. There is a fair number of pine trees surrounding the house.
 

mmckenna

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So, looking up the Viper site for your county, it's all running at 852MHz range.

RG-58 coaxial cable is extremely lossy on those frequencies. Depending on how long your coax run is, that could be the issue.

If you coax run was 50 feet (example), you'd lose 80% of your signal just in cable losses. If your cable run is shorter, the losses are going to be lower, but likely still significant.

Foliage can attenuate the signal a little bit, but usually not enough to make that much difference. Local topology between you and the tower site will make a bigger impact. If it's a clear line of sight between your antenna and the tower (ignoring the trees), then it should work with good coaxial cable. If there is a hill/mountain in the way, then you might have issues.

So, the big question now is, how long is your coaxial cable? Upgrading to better cable -might- be the answer.

Antenna type can impact things a bit, if it's not designed for use at 800MHz, but I'm going to think the coax is the bigger issue.
 

FW2518

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The antenna run is only 25 ft. What type of coax do you recommend ?

I forgot to mention that I bring a hand held radio from the fire station and it picks up a lot that the home patrol does not. That is why I think I'm missing a lot.
 

mmckenna

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The antenna run is only 25 ft. What type of coax do you recommend ?

I forgot to mention that I bring a hand held radio from the fire station and it picks up a lot that the home patrol does not. That is why I think I'm missing a lot.
The transceivers usually have better receivers than a scanner will.

Also, you may have interference from a strong nearby cell tower, simulcast distortion, or any number of issues.

25 feet is still kind of a lot of RG-58. As said above, RG-6 might work better, but there are a lot of things that will work "better" than RG-58. A run of LMR-400 might be a better choice. You can purchase it with connectors pre-installed. Get one to match the base of the antenna. At your scanner end, terminate the LMR-400 with a female N connector, then get yourself a male N to SMA or BNC, whatever your scanner uses. The short jumper should be made out of a smaller diameter, more flexible cable. That'll take strain off the antenna connector.

Now, as for your antenna, it would be useful to figure out what that is. Any chance you can snap a photo of it?
 

FW2518

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I have a picture but I don't know how to drop it into this message block or attach it.
 

FW2518

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Picture

A picture of the antenna in question can be seen at the link in the trackback
 

FW2518

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The transceivers usually have better receivers than a scanner will.

Also, you may have interference from a strong nearby cell tower, simulcast distortion, or any number of issues.

25 feet is still kind of a lot of RG-58. As said above, RG-6 might work better, but there are a lot of things that will work "better" than RG-58. A run of LMR-400 might be a better choice. You can purchase it with connectors pre-installed. Get one to match the base of the antenna. At your scanner end, terminate the LMR-400 with a female N connector, then get yourself a male N to SMA or BNC, whatever your scanner uses. The short jumper should be made out of a smaller diameter, more flexible cable. That'll take strain off the antenna connector.

Now, as for your antenna, it would be useful to figure out what that is. Any chance you can snap a photo of it?
I have found the packaging for the antenna. It is a TRAM model 1465 base ground plane antenna . It has 4- 20 1/2" ground plane radials. I cut the vertical antenna back to about 2" for the 800 MHz signal that we are receiving . It has a SO-239 connector on it.
 

mmckenna

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I have found the packaging for the antenna. It is a TRAM model 1465 base ground plane antenna . It has 4- 20 1/2" ground plane radials. I cut the vertical antenna back to about 2" for the 800 MHz signal that we are receiving . It has a SO-239 connector on it.
OK, that part number is the ground plane kit. What are you using for the vertical radiator?

2" is too short for 800MHz. 3.5 inches would land you closer to the 850MHz range. 2 inches is closer to quarter wavelength on 1500MHz.
 

FW2518

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After Hurricane Irma passes I'll get the antenna down and change it to 3.5 " and see if it helps. Thanks
 

mmckenna

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After Hurricane Irma passes I'll get the antenna down and change it to 3.5 " and see if it helps. Thanks
That should help if it's a 1/4 wave antenna. If it's got a base coil (not a 1/4 wave), you'll need to figure out exactly what it is and if it'll work at 800MHz.
 

peten1vak

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My 2 Cents

Regarding the Pamlico County Viper system:


I am in Pamlico County at least once a week for my job. I have been all over Pamlico County and always had a strong signal from the Viper system no matter where I've been. I have a Tram magnetic mounted antenna on the car but I have also used the stock antenna for my Pro 668 at times and still have been able to receive the signal very strongly. I am also able to receive Craven County Viper throughout the entire County. Just my two cents but I have been all over that County in a mobile and have never had a problem with the signal.
 

FW2518

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I have a good signal in Merritt at the postoffice. But as I come down Florence Road the signal drops. I think my location has a lot to do with it.
 

FW2518

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The antenna is longer than the 2" I reported. Maybe close to the 3 1/2" that you suggested. I'm going to order a 20' LMR-400 cable today to replace the 25' RG-58
 

troymail

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I have poor reception of multiple Brunswick County VIPER sites inside my house but pretty good outdoors and mobile. A couple are 8-9 miles (max) from me. I've even heard system users along the ocean complain about poor communications and end up using a phone to call into the dispatchers.

If you are using an external antenna and still have poor reception it certainly would seem there could be something damaged or defective in that setup and/or it's just in a dead spot.

Having said that -- if you are monitoring more than just VIPER - or even more than one VIPER site with your Home Patrol, it is likely that is at least part of the reason for missed comms as well. I typically run multiple radios at the same time (Whistler, Uniden, Unication) and I can see a radio receiving activity while others (particularly the Uniden; the Unication will miss things due to known issues with missing the initial channel grants) just scan right through a system/site past an active talkgroup without any indication it saw anything....(i.e. I see the system go by on the display and it stops on nothing). The more I'm scanning in terms of variety of system types, the more I see the Uniden miss. I've never fully confirmed it but it also seems like if I am in "ID Search" mode, it misses even more (which really makes no sense at all since in ID Search, it should be stopping on everything except talkgroups I have locked out.

A good test would be to hold on a specific talkgroup and/or increasing the "hold" time on the system from the default 0 to something higher (if that is an option on the Home Patrol). The less the radio is doing, the more likely it will hear most everything (that's the way "real" subscriber radios work unless they are in some form of scan mode).
 
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FW2518

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We are making progress. I got the antenna down and measured the vertical element. It is 3 1/2" from the top to the base where it meets the connection. I have changed the RG-58 with a 20 foot LMR-400 cable and it seems to have made a difference. Now I need to get through the side of the house ( standard stick built house) and then replace the 10 feet of RG-58 unside the house with LMR-400. Any ideas how to get through the 4" outside wall of the house. I have a hole now (1/2") but I need to clean it up and make it weather tight.
 

Bearfoot

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We are making progress. I got the antenna down and measured the vertical element. It is 3 1/2" from the top to the base where it meets the connection. I have changed the RG-58 with a 20 foot LMR-400 cable and it seems to have made a difference. Now I need to get through the side of the house ( standard stick built house) and then replace the 10 feet of RG-58 unside the house with LMR-400. Any ideas how to get through the 4" outside wall of the house. I have a hole now (1/2") but I need to clean it up and make it weather tight.
I'd run it through a piece of PVC with a 90* elbow facing down to keep water out.
Once the cable is in place you can fill the end with a good silicone caulk and use spray insulation to fill the tube.
 
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