Antenna Troubleshooting: Part 2

First of all- let me thank all of you for the assistance you provided me through the original thread. I have taken all steps and am still having issues. I have swapped out the amplifier/splitter with the Electroline 8-port model. I have redone all ends with compression coax and BNC connectors. I mounted the antenna high on the side of my house, away from the chain link fence. I added an FM trap. I swapped out the balun on the antenna. I am still having problems picking up the NJSP 700/800 system, which has the tower about 10 miles from my house. I cannot get the JCP&L system which is on 935 MHz, BUT- I can get NYFD on VHF. It appears my VHF is amazing, and the height boosted my UHF also. For some reason my 700, 800 & 900 MHz stuff is really crappy and full of static. I am all out of ideas- I am pleading with you fellow RR members! What is wrong?

Questions

Where are those eight coax cables going to? The Pro-97 was mentioned in your first post. What others on this setup? The antenna looks great up in the air! The amp nice and clean setup. Did you re check your coax for shorts? Center conductor to shield? What about programming in the scanner any attenuation set for any of the control channels? Anything get L/O by accident? Proper trunking tables? What squelch setting? Can you still hear with a rubber duck antenna only? Other bands are working? How's the marine band can you hear fishing boats? Weather from NOAA? Military at Fort Dixx?

Everything is working great on the other bands, just very poor 700, 800 & 900 MHz. I live 60 miles from NYC, and I am picking up NYFD on their VHF channels. I am getting all of the next county north of me (Monmouth) also. Cable is the standard 25 feet of RG-6 that came with the antenna in the box from Radio Shack. Yes I can get the 380 MHz NAS Lakehurst system. I can even pick up 4 different NOAA weather stations! I did not inspect the full length of the coax, as I am assuming it is in good shape as it was taken new from the box. The antenna was also new in the box. The Electroline 8-way drop amp goes to 8 various scanners. The bad reception is across all scanners. I even tried running the antenna straight into a handheld scanner- and the signal was slightly poorer without the drop amp.

My thoughts may be a defective antenna, or some kind of interference that is causing the high bands to not be received. My house is also at a low part of town- maybe a few feet above sea level.

So you checked your programming no attenuation or l/o's? No trunking table issues? You don't answer all of my questions so I find myself guessing those things are not checked yet? Can you send me a copy of the scanner file and tell me what program you use to make it? Send a pm and I'll send my email address.

Did you ever try the different coax run?

Here are some ideas. They may have been mentioned in your original thread.

If there is a cell phone tower within a 1/2 mile, that among other things, could cause some issues. Your choice of coax is nearly the worse. I would encourage you to get on the roof and hook a short jumper from your antenna right to your scanner so you know what you are working with right at the source. You have to know your baseline.

Remember, the higher the frequency, the higher loss you will have with your coax. 25ft isn't a lot, but it might just be the problem. You will find that out when you get on the roof with a 3ft jumper.

I know what the reviews say, but this antenna is very directional. I let mine sway in the wind and I can tell which way it is facing by what I am hearing. Make sure it is facing the direction of your 800mhz signals.

There are a bajillion things that can be causing this. Be patient and work on them one by one. Part of the fun of the hobby is the challenge. We learn as we go.

Alright, here is a quick reply before work.
The closest cell phone tower is either less than a mile, or 5 miles. I need to verify. As for coax, I am open to suggestions. If someone wants to be so kind as to post a link to what the best would be, I would appreciate it. I have about a 20' run from the antenna to the drop amp. I will get on the roof and try the jumper on my next day off. It is aimed kind of halfway towards my 700/800/900 signal towers, and North to pick up Monmouth County. Again, the VHF is beyond amazing... UHF is better, and high band is crap.

To answer 737mech:
Where are those eight coax cables going to?
-3 PRO 163s, a PRO 652, PRO 2053, PRO 2039 & PRO 2050. Then one lead goes to another drop amp to 8 more scanners that I use sparingly.

Did you re check your coax for shorts?
-I did not inspect the entire length of cable, I simply assumed it would be in good shape as it came new in the box from Radio Shack. I did replace the factory crimp end on the antenna with a compression. Should I do the same on the other end?

Center conductor to shield?
-I believe I am okay on this, but a little elaboration would be tremendously appreciated.

What about programming in the scanner any attenuation set for any of the control channels?
-Checked the ATT, and it is NOT on for any of my control channels. The poor reception has been duplicated with every scanner on the amp, and when I did a direct run right to a handheld.

Anything get L/O by accident?
-Checked, and again I am good.

Proper trunking tables?
-Yes, these scanners were programmed by WIN500 and WIN97. I moved to this house about a year ago. My old location was much higher in town and I picked up everything. The programming of the scanners has NOT been touched since I moved.

What squelch setting?
-Squelch is right, it is right above the static threshold

Can you still hear with a rubber duck antenna only?
-Inside, no. Outside in my driveway, I can pick up the high bands with a handheld and rubber duck.

Other bands are working?
-VHF is amazing! NYFD on VHF and I am 60 miles away. All VHF on the next county north of me is killer. UHF is improved, but the distant 500 stuff is hard to pull in. As the frequencies go higher, my reception is poorer.

How's the marine band can you hear fishing boats?
-I have never tried, but I can check. The ocean is about 8 miles from my house.

Weather from NOAA?
-I can pick up four NOAA weather channels with the new antenna up high.

Military at Fort Dix?
-380 MHz trunked system comes in perfect.

Those antennas just aren't that great at 800.

^^This^^ is what I was thinking. With all those radios, put up an additional dedicated 800 MHz antenna and only use it on the radios monitoring 800. There are always compromises running a single antenna for all-band use, especially when you have the means of easily running dedicated radios on specific bands of interest. I have no experience with the ST2, but I do have some with the RS Discone. It is also quite good on VHF/UHF, but not even close to what I get on my dedicated homebrew 800 MHz antenna. Yes, it works, but for me, I wanted the best available because 99.9% of what I monitor is 800/700.

EDIT: Also, I have to ask -- why all the rigs?? Do you stream all these feeds or something? I get lost as it is monitoring 2 or 3 systems at one time. LOL

To check for a short between center conductor and shield you will need a multimeter set on the Ohm scale, some have a tone setting. Disconnect both ends and at one end put the red lead to the center conductor and the black to the outside of the connector- if the meter zero's out or you get a tone you have a short.

Also have you tried running straight from the antenna to the scanner eliminating the splitter to see if that helps?

trap5858 said:

Also have you tried running straight from the antenna to the scanner eliminating the splitter to see if that helps?

Click to expand...

That's a good suggestion, and the same as was posted earlier in this thread, i.e. get on the roof / ladder and connect a short (3 to 5 foot) coax jumper directly from the ST-2's 300 to 75 ohm balun to your handheld scanner. You'll need a 75 ohm jumper cable and an adapter for the end that goes to your handheld scanner. If this test improves signal and your handheld receives the freqs above 700 mHz better than it does at the other end of the coax and all of those splitter / amps.... then the problem is definitely in your coax run or the splitter / amps. However, if the handheld scanner is just as weak when connected via the short jumper on the roof / ladder.... the problem is the antenna.

Other than your handheld, what manufacturer and model are your other 8 scanners?

The fact that the handheld works better with only the duck is not surprising, as handhelds don't have the front-end capabilities to handle a wideband outdoor antenna unless you are waay out in the sticks. One tends to suffer from desensitization, overload and intermod.

I suspect desense as the first problem. Do any channels have better reception with the scanner's own attenuator activated? If so, that is a weak attempt by the scanner to control desense / overload. I'd remove the amp and try the attenuator again and see if it improves further.

It seems like a backwards step, but many new users immediately overload their inexpensive / handheld scanners with much improved antenna setups, forcing them into better radio hardware to deal with it. Inline filters and whatnot only go so far.

For kicks, try activating any "close-call" features, and see if your scanners just consistently lock up on anything active. Make the squelch tighter and tighter, not just above the noise floor. This might help identify some constant carriers / services that you *may* be able to filter out with more inline filters.

First thing is - what exactly are your stable of scanners?

He posted the scanners a few Pro-163'a a pro-652 and a few older models. I was also thinking overload in his prior post and suggested the rs fm trap to try. I don't remember is that ST-2 directional? Try turning it another direction.

A 25' run of that coax should not kill your reception around 900 MHz. I have the ST2 and it works best on VHF vs UHF when compared to a Radio Shack discone. I am thinking the problem lies with the ST2 and the frequency you are having trouble with.

Perhaps a home built or store bought 900 MHz yagi will resolve your issue. You may be getting blasted by a signal or signals that are wiping out the upper band. Signals much lower than 900. If you add a directional 900 MHz antenna on that pole, it should help with rejection of unwanted signals by focusing the reception to the freq and site you want. Right now that ST2 is working very well to receive everything but 900, and based on your notes it appears it is working perfectly...unfortunately. Even an omni 900 would be a better option than the ST2 for that frequency range.

Congratulations on putting up an antenna that is doing very well 300 MHz down. Leave it alone and add an antenna tuned for 900. I would throw LMR-240 coax on the 900 antenna, but 25' of most any other coax should work if you already have it with that short run.

Someone might make a 7/8/900 MHz band pass filter and you could put that inline with the specific scanner you want to use for 900, but the filter probably costs more than a properly tuned antenna. I would just add the additional antenna.

Any suggestions on an antenna that will pick up 700/800/900 MHz?

737mech said:

He posted the scanners a few Pro-163'a a pro-652 and a few older models. I was also thinking overload in his prior post and suggested the rs fm trap to try. I don't remember is that ST-2 directional? Try turning it another direction.

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737, this might not be his problem, but I will admit to learning MY ST2 is apparently more directional than I thought. Using mine for aircraft freqs , and it had been picking up the RCAG near Birmingham for months until a couple of weeks back. Being quite busy, and using other scanners, I didn't check it right away, then finally walked out and looked at the antenna-it had gotten blown around by the wind and was no longer facing southward, where it had been pointed. In other words, the antenna was giving me an east/west angle when it had been north/south. Once I re-aimed it toward the south, I got my Atlanta atc back again, and the Bham approach stuff. I really didn't think it mattered that much with an omni-directional, but it does here.

If you suspect very strong signal(s) in the 700-900 mHz range are blasting your location, buy an inexpensive RTL-Software Defined Radio (SDR) USB adapter such as those made by NooElec (check Amazon or eBay... less than $25) and run SDR# (SDRSharp) or other software receiver. The waterfall / bandscope that appears should tell you pretty quickly whether there are strong signals appearing in that freq range... and potentially overloading your system. It would also be useful in checking the output of the splitter / amps you have to determine if there are unwanted signal components being amplified... or desired RF being attenuated to a high degree.

KC2GVX said:

Any suggestions on an antenna that will pick up 700/800/900 MHz?

Click to expand...

Yes - no kidding a groundplane made up of 3-inch elements (about half the size of the 70cm band), or perhaps a vertical dipole, each element 3 inches long. Easy to whip together for testing.

What I can say is that all of my RS / GRE made desktop scanners (I have the 163 as well) are very prone to overload at 800mhz with large antennas and a high rf-environment and especially so with broadband antennas. Much more so than Uniden. Still, these are consumer-level scanners.

I also own the 163, and just want to make sure you have tested both with and without the attenuator (G / GA or nothing in the display).

Are signals *without* the amp better with the attenuator on or off?

That's where you should start since a rubber duck dummy load not even tuned for 800 works better on a handheld that is also easily overloaded.

First off, I am no radio expert. I have an ST-2 connected to my Uniden BCT-15X with the 50' coax that came with the antenna. The antenna is about 30' in the air. I monitor Racom's Edacs 800mhz system. I have two towers programmed into my scanner. One is about 1/2 mi from my house (I can see it from my deck), and another one about 30 miles away. The one 30 miles away comes in just as strong as the one 1/2 mile away, (according to the bars on my scanner). No difference in the sound either. The ST-2 seems to work fine on 800mhz for me. Just my 2 cents. That's probably all it's worth.

Hmm. Your signals on high frequencies may be attenuated because of the splitter. Have you tried connecting the antenna directly to the scanner from the antenna? Its almost like the distribution is acting like a high pass filter.

I also have a ST2, and it works great on 700-800mhz. I find it hard to believe you aren't hearing better on yours.