Hello, I’ve been trying to setup a scanner but am having problems. My goal is to get it to pick up a county dispatch a few counties away (65 miles). I extended a firestik all band antenna (model MSB-RX) 20 ft. high and ran a cable down into the house and into the scanner (Uniden BC144XL). The county dispatch I’m trying to receive dispatches some departments on low band and others on high band. Once I set it all up, I can pick up the dispatch when they are dispatching on low band but it picks up nothing on the high band frequency when they dispatch on it. However, I operate a scanner in my truck with an antenna only about 18 inches high and it can pick up the high band frequency from this county while sitting in the driveway and close by. It is not very clear but I figure if my truck can pick it up somewhat, surely the scanner inside the house with the 20ft antenna should. This has me puzzled…any suggestions? Thanks.
Scanner Antenna Problems
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mjthomas59
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You might check to see what the dispatch power output is on lowband vs. vhf-hi(i assume this is what you are refering to when you say high band). It is possible that the lowband dispatch antenna is mounted higher, the dispatch center may have more wattage going out on lowband, etc. There are certainly some variables to consider although it does seem strange that you pick it up from your truck and not on the base. You might try switching over to a discone from RS if you are cheap like me and see what happens. I can monitor VHF-HI frequencies from about 50 miles with it, and it is sitting in my basement not even outside in the air. Just a thought.
DPD1
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It sounds like the longer roof antenna is hearing the low band stuff better, and since the one on your car is shorter, it's actually better for the higher band stuff. Both your base and car antennas are probably basic 1/4 wave. The bottom elements on the base one are your ground plane, and your car roof acts as the ground plane on the mobile. Also... If you're not using good cable, the low band stuff will have less loss on the base antenna cable than the higher band stuff, so some of your higher band stuff might be getting lost there. 18" is about where 2M ham would be, so VHF stuff would be good on that. If you mean 800 MHz type stuff for high band, it's going to be hard getting distant low band AND 800 well in just one antenna. You would either need two dedicated antennas, or one multi band directional antenna with some gain.
Dave
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Dave
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- Custom Scanner, Aviation, MURS, GMRS, Marine & Ham Antennas -
DPD1 makes all good points, so with that said, your fix would be a better multiband antenna, and maybe a change in coax. Your firesitck may be an all band but it seems to favor low band. Do you have a link to the firestick you are using? I could suggest something better for high band if I seen what your current setup is. Also as DPD1 said, a step up in coax quality may help as well, though it sounds like you have a short run. Mjthomas59 suggested the radio shack discone, a good cheap option, the best part is you can try it free, if you dont like it they will take it back, so it may be a good first step. There are too many options to list, and its easy for me to say some LMR400 coax and an expensive antenna will work without a doubt, but I'm sure you'll want to try some more simple and inexpensive options like the ones the others suggested above. Good luck, let me know if you want some suggestions on an antenna that will perform better then the firestick.
Scott
Scott
Make sure the base antenna you are using is designed for the bands you want to receive. Do no skimp on coax, the higher the frequency, the greater the loss through coax. So if you design your base antenna for the higher frequency (with an antenna that will pick up low band) you'll be better off.
I had a similar problem recently and bought a filter from Scanner Master that did two things; filter out signals below 25 MHz and filter out (30dB) the FM broadcast band. Once I had the base antenna installed, AM & FM broadcasts were bringing down the AGC. When I added the filter, my reception, especially on VHF hi, went up.
I had a similar problem recently and bought a filter from Scanner Master that did two things; filter out signals below 25 MHz and filter out (30dB) the FM broadcast band. Once I had the base antenna installed, AM & FM broadcasts were bringing down the AGC. When I added the filter, my reception, especially on VHF hi, went up.
Thanks for the replies everyone. The frequency areas i'm trying to pick up are in the 155Mhz area. The cable i'm using with the base antenna is RG-58 and there is about 100 feet of it coming from the antenna into the house as the antenna sits on top of a hill. Does this sound like a decent cable? I also remember reading on the antenna box about a proper grounding for the antenna. What we did was take a 10 ' steel pipe and hammered it into the ground about 5 feet. Then we took four 5' radioshack antenna masts and put them overtop of the steel pipe making the total length of the antenna 20 feet high. Does this sound like a proper ground? Thanks again.
scottie84 said:
Yikes! 100 feet of RG-58? No wonder you can't hear anything. RG-58 coax is very lossy for long runs. You would probably have better results using some low loss coax like Times Microwave LMR400. I wouldn't use RG-58 for a base scanner antenna at all. Use RG-58 only for your mobile antenna. Even RG-6 coax would be better than RG-58.
I second Ken's Yikes! lol Get rid of that RG-58. If you go here
http://www.timesmicrowave.com/cgi-bin/calculate.pl you can see by the calculator that 100 ft of RG-58 at 155 MHz gives you almost 6db (5.7 to be exact) signal loss, with only a 26.7% efficiency. For every 3 db of signal loss, you effectively cut the signal level you get to the scanner in half. So in this case the signal level that reaches your scanner will only be a little above 25% of the signal that hits the antenna, all due to cable loss.
If you switched to RG-6, according to the calculator, you would get a 3.4db loss and 45.9% efficiency, thus would get a little under half of the signal to the scanner - some improvement. Whereas if you switched to LMR-400, you would see a 1.6db loss and get 69.8% efficiency. So you can see the cable does make a big difference.
Good luck with your project. I think you will be happy with the results of upgrading your cable.
http://www.timesmicrowave.com/cgi-bin/calculate.pl you can see by the calculator that 100 ft of RG-58 at 155 MHz gives you almost 6db (5.7 to be exact) signal loss, with only a 26.7% efficiency. For every 3 db of signal loss, you effectively cut the signal level you get to the scanner in half. So in this case the signal level that reaches your scanner will only be a little above 25% of the signal that hits the antenna, all due to cable loss.
If you switched to RG-6, according to the calculator, you would get a 3.4db loss and 45.9% efficiency, thus would get a little under half of the signal to the scanner - some improvement. Whereas if you switched to LMR-400, you would see a 1.6db loss and get 69.8% efficiency. So you can see the cable does make a big difference.
Good luck with your project. I think you will be happy with the results of upgrading your cable.
Third on the Yikes! LOL Like I said in my last post, LMR400, didn't know you had a 100ft run or I would have pressed that issue.
That really is not proper grounding. An option would be a grounding block that goes between the antenna connection and the coax, it's just a way to connect a ground wire to the shield of the coax. It keeps it nice and clean and water tight with some coax seal. You would run a copper strap or large gauge copper wire off of it down to a copper clad grounding rod that is hammered into the ground. Copper clad steel grounding rods can be bought at Lowes or Home Depot. Everyone has their own opinion about grounding and where to do it. I have all my radios and base scanners grounded to a bus bar "big copper bar" which is connected to an earth ground.
Scott
That really is not proper grounding. An option would be a grounding block that goes between the antenna connection and the coax, it's just a way to connect a ground wire to the shield of the coax. It keeps it nice and clean and water tight with some coax seal. You would run a copper strap or large gauge copper wire off of it down to a copper clad grounding rod that is hammered into the ground. Copper clad steel grounding rods can be bought at Lowes or Home Depot. Everyone has their own opinion about grounding and where to do it. I have all my radios and base scanners grounded to a bus bar "big copper bar" which is connected to an earth ground.
Scott
dbox1
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COAX option
You might also consider another low cost option of Belden 1189A quadshield RG6. It's relatively flat all the way up to 1Gz, where its loss is only down 6db @ 1Ghz per 100ft, and 1.5db @ ~150Mhz per 100ft. This is better performance than some RG8 and RG8U, and close to LMR-400.
A note about grounding though, when it comes to this issue you need to take care in what and how you do it. Your life or a family member may depend on it. I prefer to use a solid copper rod at least 10 feet long. Some say use a cheaper copper clad steel rod, but over the long haul (decades) this can prove inadequate. You must penetrate the crust of the earth more than 4~6 feet, and in extremely dry climates sometimes deeper. Iron pipe or steel isn't an adequate ground by any code standard. This is one arena you don't scrimp on. Your life or your family member is certainly worth more than $50.00 for the cost of a NEMA approved ground electrode.
You might also consider another low cost option of Belden 1189A quadshield RG6. It's relatively flat all the way up to 1Gz, where its loss is only down 6db @ 1Ghz per 100ft, and 1.5db @ ~150Mhz per 100ft. This is better performance than some RG8 and RG8U, and close to LMR-400.
A note about grounding though, when it comes to this issue you need to take care in what and how you do it. Your life or a family member may depend on it. I prefer to use a solid copper rod at least 10 feet long. Some say use a cheaper copper clad steel rod, but over the long haul (decades) this can prove inadequate. You must penetrate the crust of the earth more than 4~6 feet, and in extremely dry climates sometimes deeper. Iron pipe or steel isn't an adequate ground by any code standard. This is one arena you don't scrimp on. Your life or your family member is certainly worth more than $50.00 for the cost of a NEMA approved ground electrode.
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Thanks again everyone. I will start looking for the best price on a better cable and a way to ground it. As far as the PL-259 ends that I will need on each end of the cable, what type is better? I know Radioshack offers many types, some that you solder and others that are solderless. Any opinions on the better ones? Thank you.
dbox1
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Scottie, that will depend on your cable selection. No matter your cable selection, you will have to buy a screw type adapter for RG6 (F to PL-259) or LMR-400. (N to PL-259) If you choose RG8 or RG11, then solder connections are always best for PL-259 connections in my opinion.
scottie84 said:
Use the solder on connectors, but if you buy LMR400 get it with the connectors on it already as they are not easy to install properly. You should be able to buy a 100ft run with PL259 or N connectors on it off ebay. As far as the solid copper grounding rod, I never thought whether they made them or not, with the price of copper now they may be 200 dollars! I've been to Lowes and Home Depot and never seen them, where do you get these at? I would think they would be a ***** to get in the ground where I live, the beating I put on the copper clad steel 8ft rod was crazy, a solid copper rod would not have held up to that.
Good luck, get that coax changed out for something low loss regardless of choice, you will notice a considerable difference.
Scott
dbox1
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Scott,
You can visit your local electrical contractor's supply for a NEMA approved rod. Your local ACE hardware store should also carry them. There are steel heads for driving the copper rods so you don't damage the rod itself. Copper clad rods do meet code, but that's just my personal preference if I can get my hands on one. It has been a couple of decades since I have set mine up and yes, copper prices are sky high these days. The last one I got my hands on was from the local electrical company from a friend.
Harger sells solid copper rods, and if you do not have driving equipment, you can drive 5/8 rebar down 3/4 of the way down with a sledge, pull it back out with a high lift jack and a chain, and then drive the copper rod the rest of the way. ( http://www.harger.com )
You can visit your local electrical contractor's supply for a NEMA approved rod. Your local ACE hardware store should also carry them. There are steel heads for driving the copper rods so you don't damage the rod itself. Copper clad rods do meet code, but that's just my personal preference if I can get my hands on one. It has been a couple of decades since I have set mine up and yes, copper prices are sky high these days. The last one I got my hands on was from the local electrical company from a friend.
Harger sells solid copper rods, and if you do not have driving equipment, you can drive 5/8 rebar down 3/4 of the way down with a sledge, pull it back out with a high lift jack and a chain, and then drive the copper rod the rest of the way. ( http://www.harger.com )
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I'll check it out, I'm glad to hear the others meet code as I have used them more then a few times. Here in OK, if someone knew I had a solid copper grounding rod, it would be gone over night. You would not believe the places they steal copper from, a guy just died trying to steal it from a billboard, he got a big piece loose and hit some near by power lines with it! They usually steal it from equipment that has extensive grounding systems. I think they are getting 4-5 bucks a pound for it. I would just rather steal cows and cut out the tenderloin, I can get 15 bucks a pound for that LOL!
Scott
Scott
dbox1
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Scott,
I'm here in OKC, so I know what you are saying. Just so people will know what is the guidelines..
NEC 1999 Article 250-52.3 (Summarized)
The electrode shall be installed so that 8' of length is in contact with the soil. It shall be driven to
a depth of not less than 8' except where rock bottom is encountered. In the case of bedrock, the
electrode shall be driven at an angle not to exceed 45 degrees from the vertical or shall be
buried in a trench that is at least 2-1/2' deep.
UL467 9.2.1 (Summarized)
A solid rod electrode of copper or other suitable non-ferrous metal, or a solid rod electrode of
iron or steel with a copper or other suitable non-ferrous metal or stainless steel jacket, shall have
a diameter not less than 1/2" thick.
Soils in Oklahoma are acidic, so your grounding system should be checked at least once every decade, since galvanic material will degrade over time.
I'm here in OKC, so I know what you are saying. Just so people will know what is the guidelines..
NEC 1999 Article 250-52.3 (Summarized)
The electrode shall be installed so that 8' of length is in contact with the soil. It shall be driven to
a depth of not less than 8' except where rock bottom is encountered. In the case of bedrock, the
electrode shall be driven at an angle not to exceed 45 degrees from the vertical or shall be
buried in a trench that is at least 2-1/2' deep.
UL467 9.2.1 (Summarized)
A solid rod electrode of copper or other suitable non-ferrous metal, or a solid rod electrode of
iron or steel with a copper or other suitable non-ferrous metal or stainless steel jacket, shall have
a diameter not less than 1/2" thick.
Soils in Oklahoma are acidic, so your grounding system should be checked at least once every decade, since galvanic material will degrade over time.
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Oh, didn't know you were in OK, are you a licensed amateur? I've always wanted to set up a good grounding system with 3 rods in a triangle spaced about 6 feet apart and have them linked. I have heard that is the best way to go, I think 6 feet is what I was told.
Scott
Scott
Impedance
Yikes on using 100' of RG-58!!!
1. Keep the length of the cable run to a reasonable minimum. For example; don't use some pre-made 100' length if you only need 75'. Every extra foot of cable is a little more loss.
2. Match the impedance. All of the scanners I use have 50 ohm antenna connections. Use an antenna intended for the job, of the same impedance as the scanner, and match the impedance of the coax. Some will say they don't notice a difference using 75 ohm coax on a 50 ohm system; but I differ. If you get 1 dB less loss, that's one more dB of signal.
3. Don't skimp on coax quality. Cheap coax is cheap for a reason. Loss loss coax costs a little more for a reason. If you are going through all the trouble of doing this (so you can hear as well in the house as in your truck in thr driveway), then isn't it worth doing the best possible?
4. Connectors. Keep the number of adapters to a minimum. I've actually got a PL-259 on my antenna end, BNCs inline to connect to a filter, and a BNC to terminate into the scanner. I used RG-8 from the antenna, and then lighter coax to the scanner (having RG-8 all the way to the scanner, unless it is a base model, is tough to deal with). Connectors are required; but each adapter will have some insertion loss.
Good luck.
Yikes on using 100' of RG-58!!!
1. Keep the length of the cable run to a reasonable minimum. For example; don't use some pre-made 100' length if you only need 75'. Every extra foot of cable is a little more loss.
2. Match the impedance. All of the scanners I use have 50 ohm antenna connections. Use an antenna intended for the job, of the same impedance as the scanner, and match the impedance of the coax. Some will say they don't notice a difference using 75 ohm coax on a 50 ohm system; but I differ. If you get 1 dB less loss, that's one more dB of signal.
3. Don't skimp on coax quality. Cheap coax is cheap for a reason. Loss loss coax costs a little more for a reason. If you are going through all the trouble of doing this (so you can hear as well in the house as in your truck in thr driveway), then isn't it worth doing the best possible?
4. Connectors. Keep the number of adapters to a minimum. I've actually got a PL-259 on my antenna end, BNCs inline to connect to a filter, and a BNC to terminate into the scanner. I used RG-8 from the antenna, and then lighter coax to the scanner (having RG-8 all the way to the scanner, unless it is a base model, is tough to deal with). Connectors are required; but each adapter will have some insertion loss.
Good luck.
dbox1
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A half wave dipole antenna is nominally 75 ohms impedance (which is why you find this coax used in wide band coverage in OTA antennas as it is coupled with yagi design) while a half wave folded dipole antenna is nominally 300 ohms impedance, a quarter wave antenna with drooping quarter wave radials exhibits a nominal 50 ohms impedance, and lastly, a helix at 140 ohms impedance.
If you are transmitting, I would be a little more discriminate in my coax's impedance in relationship to the antenna used, but receiving, it is less critical. Antennacraft's ST2 is a 75 ohm antenna.
If you are transmitting, I would be a little more discriminate in my coax's impedance in relationship to the antenna used, but receiving, it is less critical. Antennacraft's ST2 is a 75 ohm antenna.
Thanks again everyone. I just found a site that sells the LMR400 cable, the PL259 ends for it, and grounding materials. I'm getting ready to place the order for everything I need and as soon as I get everything installed, I'll let everyone know how it works!
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