What happened to my reception? Base Antenna gone bad?

[safetyobc]

I am currently using a Pro-2052 connected to a Scantenna or otherwise know as a ST-2.

I have had good luck with this antenna and have enjoyed using it. Always had good reception on VHF-High which is my primary listening. Last week, I noticed that I was only hearing local stuff on the scantenna for some reasons. Where I have been hearing 2 and 3 counties over from me, is now gone. Several agencies I can't hear.

I connected the BCD396T to the antenna to see if it was the Pro-2052 but same resuts.

There have been no ligtening strikes here in recent weeks (until last night but no hit on my antenna). I pulled the antenna down today to check connections and everything looked like it did when I put it up. No corrosion, nothing. It has been up for about 1 year.

Any ideas what is going on? Maybe just a bad week for receiving here in Arkansas? Coax gone bad? How long does coax last? It came with 50' of RG-6 which is still on there.

Just for reference here is the antenna I bought. http://www.antennawarehouse.com/Scanner/Scantenna.htm

Any suggestions would be appreciated.

 

[kibbins]

I'm sure someone else will chime in but I'm sure there is a way to test the coax either with a meter or with a different antenna to rule out the scantenna. I assume a connector could have gone bad or had water penetration. Could an element of the antenna be broken that is difficult to see?
I guess it could just be bad weather for receiving. Can you confirm with a portable that the "other" counties are still broadcasting in the freqs you are expecting? i.e. drive over closer and see where you hear them and/or where you lose them... Any patch cables, adapters or grounding block in line?

 

[W4KRR]

Could be:
Water got into the coax, coax got shorted somehow, lightning or static, even if you don't believe there were any thunderstorms nearby, corosion in some part of the antenna, bad coax connectors.

Disconnect the coax from the scanner, and check the coax with an ohmmeter. It should not show a short between the center pin and the braid, unless it's a grounded antenna. Inspect the antenna for signs of corosion or damage. Try replacing the coax connector at the antenna, then the one at the scanner end. If no improvement, replace the coax and connectors. If still no improvement, replace the antenna.

 

[RevGary]

One other consideration... and I HOPE that this is not the case.

In the mid 60's, due to antenna political correctness, some radio enthusiasts fell victim to a 'prank' that showed the same type of reception problems that you are seeing. An irate neighbor who detested antennas on a home nearby because it 'looked' bad, would take a straight pin, jam it into coax so the braid and center conductor would be shorted, clip off the head of the pin at the black insullation and use a black Magic Marker to cover up the shiny part of the pin. This was known to destroy transmitters back then and create reception problems for a receiver. If any of your coax is accessable to others, carefully check out that section for this possible issue.

If you have a digital meter, place it on the RX10,000 scale and with BOTH ends disconnected from the radio and antenna, take a resistance reading from the center conductor to the outer shield. It should read Infinity (open). DO NOT touch the metal probes with your fingers because the resistance through the salt water in your body will show up on the meter. If you get ANY resistance reading, you have a bad connector, water infiltration at a connector or a short/partial short somewhere along the length. If that checks out OK, measure resistance using the RX1 scale from one end of the coax center conductor to the other ( if you can get both ends close to each other somehow ). The reading center to center should be less than 1 ohm for a 50 foot run. Do the same with the outer shield end to end. Should be the same reading. If that's all OK, then the antenna may have taken a hit somehow... bird damage, rainwater, cracked insullator(s) at the mount - just inspect it carefully. Please let us know what you find.

 

[K8PBX]

If the coax checks good, try replacing the little 300 Ohm to 75 Ohm balun/transformer.

 

[safetyobc]

I thouroughly checked the antenna this morning. Also carefully looked over all the coax.

I am suspecting maybe water damage to the coax. I never really "sealed" the connection at the antenna to the coax. It connected via N connectors from the 300 to 75 Ohm antenna feedline Balun to the coax. It had a rubber boot that slipped over the connection and I just used black tape to cover it. :roll: Dumb I know now but 1 year ago, I didn't know that it mattered. I don't have any of those meters you guys are talking about. I will likely just pick up a run of coax and try that first. I don't think the antenna is bad.

I know for a fact that other agencies are still using the same freqs because the Pro2051 in my truck still picking up the agencies.

Thanks for all the good info. I appreciate it!

 

[jim202]

One check that I always maker with a new antenna is to listen to the National Weather Service broadcast. The frequency varies depending on where your located. Generally you may be able to hear them on more than one frequency. Make a mental note of just how strong the broadcast is and on what channel. That way if over time, your antenna system may become the focus of a problem, you have something to base the operation of your receiver on.

 

[LarrySC]

I've been using the larger version of the scanntenna for many years. Channel Master 5094-A and it uses the same 75/300 ohm balun. I have an antenna at my office and two at home, one of which is connected to radios in my shop. I also gave my son-law one. I purchased 6 of these baluns as they go out from static electricty or small amounts of lightning. I only have two left and will soon order some more. The Channel Master # is 0089. I would keep at least two in stock at all times. You should check with ohm meter and get a reading across any and all leads if balun is good. If its open, trash it. Good Luck.

 

[safetyobc]

Huh, yesterday the scantenna started working as it has in the past. Picking up very distant VHF-High band. Good reception.

I wonder if maybe it was just some bad receive weather or something?

 

[safetyobc]

It happened again.

After Friday's storms rolled through (heavy rain, a little wind, a little hail) the reception went from great (listening to it earlier that day) to nothing. A few agencies that always come in crystal clear are either very staticy or un readable.

I can only assume that it is water intrusion?

It was working great, I was monitoring a neighboring county because they had a possible tornado. Then we had a tornado warning so I evacuated the family to the FD. I came back and turned the scanner on and almost nothing. I am almost certain it wasn't lightening because the storm had very little if any lightening. The antenna is not damaged. It has to be water, right?

If you read the above, this happened before but amazingly started working again. I guess the water dried up. Is that possible?

Maybe it is at the bauln thingy ma jig? Or at the connection where the bauln and the coax connect. Man I gotta get this fixed. I love my scantenna and not having it is like going without some kind of caffine or nicotine or something. It SUCKS.

Where can I get some good sealer for coax? I hope it is working again tomorrow when I get home. (at work today).

I have used a test meter thing on it but I didn't know what I was looking at. I set it on the OHMS section and then the selector on 2M. Touched the red wire to the middle wire of the coax and the black wire to the side of the connector and the meter red 0.00. But I don't know what that meant. I tried all the settings in OHM and got the same reading, 0. What does that mean? Did I have it contacted in the right spot?

thanks for any suggestions/comments.

matt

 

[mgosdin]

Matt,

That sounds like water in the coax all right.

I sealed all my connections last summer with an "Amalgamating" electrical tape. I wraped the connections clock wise then counter-clock wise twice each ( total of 4 times ) with each pass starting a little further out on the coax and stopping a little past the previous pass if possible.

Those connections have stood up to everyting that has been dumped on them by this spring's weather ( So far! ) and not shown any signs of leakage.

The big storm with the 70-mph winds did not force any water past those connections, it did force water into our Sattelite Dish's LNB. According to the technician that came out and replaced the LNB they are supposed to be water-proof. This was the first time he had seen one ruined by water.

Mark Gosdin

 

[safetyobc]

Thanks for the comments.

Do you think it will dry up on it's own again? I sure hope so. If not, I may just buy another Scantenna, coax and all. This way I can have a spare. I might stick the spare in the attic or something for another scanner?

But I hope the coax does dry out. Last time about 2 days after the hard rain, it worked perfectly again. I am hoping for the same results.

 

[TeRayCodA]

You probably don't need to buy another antenna.I would just replace the coax,and balun.

Get some silicone grease,dab a little on the OUTER threads of the balun.Instead of using the weather boot that comes with the replacement balun,use some self-fusing rubber tape to wrap the balun connection on the coax.Then,wrap a few layers of black electrical tape over it.

It is my exprience from past installs,the boots don't have a perfect fit,allowing moisture intrusion into the connection.

That should take care of your problem.

 

[mgosdin]

Matt,

It's been my experience that the coax will dry out given time. The problem is that the rain water leaves a residue and that residue, along with exposure of the conductor and shield wires to water, will evenutally degrade the coax's performance.

If you are fortunate enough the water will be confined to the connector(s) / balun only and not have gotten into the coax itself. Then it becomes a matter of replacing the connector(s) / balun and sealing them up.

The nice thing about the scantenna is that it uses RG6 and you can get that type of cable fairly easily should you need to replace it.

Mark Gosdin

 

[K8PBX]

Intermittent problems can be a challenge to solve. Being that your issue seems to be weather related, unless you plan to go up on the roof while it's raining to perform diagnosis, I'd recommend re-doing the outdoor connections and replacing some low-cost key components as a first step - when the weather is nice.

To me, it sounds like it's either a water infiltration problem or a loose connection. If you have enough slack in the coax at the antenna end, I'd suggest cutting the coax back a few inches and replacing both the coax connector and the balun. Fairly economical thing to try. Also, check where the 300 ohm side of the balun connects to the Scantenna. From what I recall, it's just a wing-nut type termination that could easily have come loose from vibration or wind movement.

To weatherproof outdoor connections, I prefer Scotch rubber splicing tape. It allows easy re-entry to the connection at a later date whereas coax-seal tends to gum things up. If the above isn't possible, then wrap the connection with electrical tape a few times, streching the tape as you wrap. Cover the connection well and wrap the tape beyond the connection, onto the coax itself, a few inches left and right of the actual connection.

One other thing... if you plan on testing your coax again, be sure to remove the balun from the coax or it could skew your reading.

 

[Al42]

Going from clear to static to clear in a few hours? It could just be static buildup causing the problem. Remember, raindrops carry a pretty good static charge. The antenna's not a grounded type, so if you don't have something bleeding off the charge, it could last for hours - maybe even a day of two.

Water soaked coax takes days to dry out, even on a very dry day. There's not much air flow inside the cable. (If you disconnect the cable from the scanner and water starts dripping out, disregard this post. )

 

[safetyobc]

Going from clear to static to clear in a few hours? It could just be static buildup causing the problem. Remember, raindrops carry a pretty good static charge. The antenna's not a grounded type, so if you don't have something bleeding off the charge, it could last for hours - maybe even a day of two.

Water soaked coax takes days to dry out, even on a very dry day. There's not much air flow inside the cable. (If you disconnect the cable from the scanner and water starts dripping out, disregard this post. )

It went from clear to static in just a few minutes, likely under an hour.

Last time it happened, it went from clear to static and didn't clear up for about 3 days. But it could be static build up I suppose? I have it grounded and have had it grounded since I put it up.

 

[timmer]

I have the same exact thing happening with my discone antenna (diamond d-130j). When we have a big rain, I'll notice a little drop off in reception. (I have a aor3000a and it has a signal strength meter). Then, after it dries up for a day or two, the reception gets better again, usually one or two bars on the meter. I believe it is a connection that didn't get sealed properly and is getting moisture in it.

 

[safetyobc]

Everything is perfect today! It is working better than ever. Listening to an 800 system at 65 miles (not typical) and all VHF-High is coming in as usual.

Weird!

 

[safetyobc]

Well, at 10:00 am around about that time anyway, the reception fell off and has been terrible since. I took the antenna down and inspected everything. Took the cover off the connection and let everything air out while I mowed the lawn.

Connected the antenna and bauln, then wrapped it up with good waterproof tape. Put the antenna back up and still poor reception!

An agency on VHF-High I normally listen to about 15 miles from me was so staticy I couldn't understand them.

I don't know what is going on? I mean, great 800 this morning (probably good ducting) and NOTHING, now.

Airband seems to be coming in decent. But VHF-High reception is horrible. Any suggestions?

matt