Not Receiving UHF

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Zeke88

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I am a complete and utter novice when it comes to scanning. I have a Uniden BC785D scanner and I just hooked it up to a new Antennacraft ST2. I mounted the antenna in the attic (had to), and the RG-6 coax runs in-wall to my den where the scanner is. The total coax run is about 30 ft.

When I first hooked it up I was amazed. I was able to hear a fire department that was about 35 miles away. They operate on VHF (154.220).

However, I really want to be able to hear a VHF police department (460.325) that is about 10 miles from here and I am not receiving anything.

I tested a bunch of other frequencies in the 460.xxx range and couldn't get any of them either. Is this not a good antenna for UHF? Is there something else I should be doing with the antenna to get UHF? Or should I be looking at a different antenna altogether?

I appreciate any advice.
 

stevecast2024

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Sounds like your experiencing a good deal of loss in your coax. Here is a quick chart for you Coax Attenuation Chart This is very common the higher up in frequency that you go. A lot of times people find that they do much better (especially in UHF and higher) with an antenna mounted right on the radio. It is very common to get excellent reception on the VHF frequencies but very poor reception on the UHF and higher frequencies when running a good deal of coax. One option might be to purchase a Pre-Amp and place it as close to the antenna as possible. This will help you to overcome some of the line loss. The Jim M75 Pre-Amplifier is a good option. A quick search will yield some options for that as well.
 

datainmotion

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Actually, RG-6 has the lowest loss of what I would call the "practical" cables, on that list, for casual scanner hobbyists - and your list shows just that.

To the OP - have you done a complete search from 450-470 or higher?
 

stevecast2024

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I agree with you on that. Don't get me wrong, but I would suggest having the user try the stock antenna on the scanner from the attic to compare.
 

datainmotion

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I agree Steve, if he has a stock antenna, it would be a good way to possibly eliminate the attic antenna and coax as issues.

Another question for the OP - did you run the RG-6 or was it already there?
 

Zeke88

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Thank you for your replies. I ran the coax in the wall when I built the house last year. It's a straight shot up and encased in closed-cell foam insulation.

The stock antenna was picking up this frequency every now and then. It was scratchy and weak and hardly readable. I don't hear anything now at all, leading me to think the coax loss may be the culprit.

I will do a search of the 450-470 range and see what happens. I may also bring the antenna down from the attic and place it a few feet away from the scanner with a short length of coax and see if things change.
 

ak4fn

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If you know a cable installer, hit him up for some rg11. I picked up 100 ft with ends for 12.50. It works great, I saw a big difference in the UHF side as compared to rg6, not as good as lmr400 but for the price I couldn't complain.
 

jim202

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The 30 foot run of the RG-6 shouldn't be an issue. I would look at the cable being shorted from the connector install. Pull the antenna off the cable in the attic. Use an Ohm meter to see if there is a short from the center pin to the outer shell of the connector. If you don't see anything, that is good.

Next you need to place a short on the end in the attic and see if you can see the shorted cable at the scanner end. If you do see the short, then your cable is good. If you don't then one of the connectors has a problem.

I don't know if the ST2 should show a short or open. So can't help you there. Try putting the stock antenna back on at the scanner and see what you hear. At this point you don't know if the scanner is working on UHF or not. Need some sort of know signal to prove the scanner is even working on UHF.
 

Zeke88

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I decided to redo every F connector in the run and I also replaced the antenna balun to see if anything would change,

I'm able to receive 453.xxx from 25 miles away, but not 460.xxx from 10 miles away. Does this seem normal?
 

ak4fn

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I decided to redo every F connector in the run and I also replaced the antenna balun to see if anything would change,

I'm able to receive 453.xxx from 25 miles away, but not 460.xxx from 10 miles away. Does this seem normal?
That could be normal, it would all depend on the wattage of one vs the other, height of either tower or obstructions between you and the antenna.
 
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