Question on Scanner / Antenna Setup

emsflyer84

Member
Premium Subscriber
Joined
Mar 22, 2012
Messages
132
Location
Central NH
Hey guys, I’ve got my Whistler TRX-1 set up in my basement with a basic antenna on the roof of the house. There was initially about 60’ of low-loss coax from the antenna, down the side of the house and into the basement to the scanner.

I then added probably a 15’ section to be able to move the scanner to another location. Since then I’ve probably added another 10’ section of standard tv coax cable to put the scanner where I really want it. I need to do some more tests, but it seems like the reception has gotten noticeable worse since that last move.

The new section of coax is kind of intertwined with other coax running cable signals to different parts of my house. Where it connects to the scanner is right near a wooden panel that has other coax coming into the house for the cable, and splitters sending the cable signal out through the house.

My question is, could a 10’ section of regular coax placed near an electrical panel and lots of other wiring have a negative impact on reception? It seems like I’m not picking things up that I was before adding the last bit of coax. It still works well but range seems to be less. Things I was getting clear before are now coming in sounding “digital” and hard to understand, and some things aren’t coming in at all.

Just looking for feedback here. Thanks!
 

mmckenna

I ♥ Ø
Joined
Jul 27, 2005
Messages
13,878
Location
SNCZCA01DS0
My question is, could a 10’ section of regular coax placed near an electrical panel and lots of other wiring have a negative impact on reception?
Yes. Other electronics can generate RF noise that can interfere with the reception of your scanner. Easy test is to try moving it far away from these possible noise sources and see if it resolves.

It seems like I’m not picking things up that I was before adding the last bit of coax. It still works well but range seems to be less.
All coaxial cable has some amount of signal loss. Cheap/inexpensive coax will have more loss than higher quality/larger cable. Adding that 10 feet will have impacted performance slightly, but likely not enough to make a big noticeable difference.
Often, the connectors are the issue. All coax connectors will add a negligible amount of loss. Cheap connectors will add more than higher quality connectors. If you have added several connectors, that could add to your issue.

Things I was getting clear before are now coming in sounding “digital” and hard to understand, and some things aren’t coming in at all.

Just looking for feedback here. Thanks!
Here's what I would recommend:
Figure out exactly how much coaxial cable you need to get from your antenna to your radio. Then add about 4 - 5 feet. Take that number, and find one of the many online dealers that will make custom coax assemblies. If your length comes out to a nice round number, like 50 or 100 feet, you can probably find pre- assembled coax that will work.
Order just the length of cable you need. No more, no less.
Order the best coaxial cable you can budget for. Times-Microwave LMR-400 is a good place to start for hobby use. You can go larger if you have a really long run, or a really big budget, but LMR-400 is pretty good stuff for hobby use. Some use RG-6 75Ω coaxial cable, like you'd use for cable TV or a TV antenna. Yeah, your scanner probably tells you to use 50Ω cable, but the RG-6 will work fine. If you use name brand quality cable, it can work well. Don't buy from "Dollar General" or some cheap Chinese brand cable. Get Belden, BerkTek or one of the name brands.

Order that cable with the exact connector you need to mate to your antenna. No adapters. Again, NO adapters. They are weak spots….
On the radio end of the coax, order it with a Type N female connector.
Then purchase a short length of RG-58 coaxial cable, no more than 2 feet or so long. Have the shop put a Male N connector on one end to attach to the heavier/stiffer LMR-400. On the other end of the RG-58 "whip", get the connector that will mate to your radio. Using the short length of more flexible cable takes the strain from the heavy/stiff LMR-400 (or larger) off the antenna connector.

When you install the new cable, make sure you waterproof the connection outside where it mates to the antenna. Do NOT skip this part. Do NOT cheap out at this point and wrap it in Harbor Freight brand electrical tape. Get a roll of Scotch 33 brand electrical tape and wrap the connection with it. Start at the top/antenna end. Wrap the tape downwards overlapping each pass by 50%. When you get down a few inches below the coax connector, carefully switch to wrapping up the connection towards the antenna, 50% overlap until you reach the base of the antenna.
If your antenna is an enclosed type, do not cover up any weep holes that may be in the base. Those let moisture out.
After you've done that, follow up with a layer of butyl rubber tape, or "coax seal" tape. Wrap this stuff around the covered connection and then mold it into a smooth covering.
Next, follow that up with another wrap of the Scotch 33 tape. Start at the top, work down, 50% overlap, then back up to the antenna.

Skipping waterproofing of outdoor connections is a rookie mistake. Water will eventually get inside and corrode things, including the coaxial cable. Don't let any one tell you it's overkill and to skip it because they've "never had a problem". Don't confuse luck with skill. The above waterproofing method is what is used on the professional side, and it works. It's also really cheap when you consider that failing to do it will let water in your cable and corrode it from the inside out.


I then added probably a 15’ section to be able to move the scanner to another location. Since then I’ve probably added another 10’ section of standard tv coax cable to put the scanner where I really want it. I need to do some more tests, but it seems like the reception has gotten noticeable worse since that last move.

The new section of coax is kind of intertwined with other coax running cable signals to different parts of my house. Where it connects to the scanner is right near a wooden panel that has other coax coming into the house for the cable, and splitters sending the cable signal out through the house.
When you route your new coaxial cable, avoid the above. While coaxial cable is shielded, some RF noise can leak out, especially if it's cheap cable or poorly installed connectors. Ideally keeping your coax and scanner away from other noise sources is a really good idea. Consumer electronics can be really big RF noise generators.
 

chief21

Member
Premium Subscriber
Joined
Mar 2, 2004
Messages
1,366
Location
Summer - Western NC; Winter - Tampa Bay FL
There was initially about 60’ of low-loss coax from the antenna, down the side of the house and into the basement to the scanner. I then added probably a 15’ section to be able to move the scanner to another location. Since then I’ve probably added another 10’ section of standard tv coax cable to put the scanner where I really want it.
Every time you've added to the original cable run, you've reduced the signal level at your scanner. You've added an additional 25' to what was already a fairly long run of 60'. And what type and quality of the cable? Are the cable types mismatched? Presumably, you've also added coupler adapters to join those new sections... introducing even more loss.
As others have suggested, your best bet would probably be to determine the best/shortest route to your preferred scanner location, trash the current coax arrangement, and replace it with a single run of quality, low-loss cable.
 

majoco

Member
Joined
Dec 25, 2008
Messages
3,652
Location
New Zealand
Chief21 beat me to it - In your opening post you said you used "low loss" coax, then there was "regular coax" and "standard TV coax" - hopefully they are all the same impedance - and as you said "standard TV coax" then it ought to be 75 ohms. What connectors did you use to join three lengths of cable?
Ideally you should as McKenna and others suggest and order one length of 50ohm LMR-400 with connectors each end to suit your antenna an your scanner so no adapters/joiners are required.
 

cmdrwill

Member
Joined
Mar 30, 2005
Messages
3,778
Location
So Cali
And be very careful, there ARE a lot of knock-off cables being sold. And LMR400 is probably the most imitated cable out there.
 
Top