SDS100/SDS200: Is scanner going bad?

[Ubbe]

I would recommend to always have a variable attenuator that can be put in line with the coax when using external antennas and adjust attenuation to see if reception improves at some attenuation level that then indicate an overload issue in the receiver.

I use antenna amplifiers and I set a scanner to analog mode and listen and adjust attenuation for best signal - noise ratio. It's easier to do when listening to an analog transmitter as a high modulated digital data signal are masking the background noise so it can be hard to hear. The attenuation level needed are often different for different frequency bands and certainly for different scanners.

There are cheap $20 ones to use that are made for sat signals and TV antennas that requires F connector adapters but ScannerMaster has one, more expensive, that does the exact same thing but with BNC connectors. If you use external antennas you'll never be really sure if you are having too much signal or have other issues if not using a variable attenuator. In some cases a FM broadcast filter might help as it is the sum of all interferences that matter. A FM broadcast filter almost always help with VHF Air reception so that filter will also be a good investment.

/Ubbe

 

[officer58]

I hate that, guess there's nothing I can do about that

But you'd think my old antenna wouldn't have worked either.

 

[K9KLC]

No, same location. Same coax.

Ok thanks. I'd stay with the original plan and try the old antenna and see if it changes back.

 

[K9KLC]

But you'd think my old antenna wouldn't have worked either.

Assuming it was working ok, then I'd switch back to that if nothing else for a test to make sure nothing else has changed along the way.

Better antenna = more signal = more interference and/or simulcast issues.

Being this close to a cell tower, this could help to explain it. I'm not familiar with that Tram antenna you have but I know a couple of guys running the Diamond and at least in one case due to interference on his end plus up here we have simulcast on StarCom 21, he actually went back to a smaller antenna and it helped him honesty receive more of what he was wanting to hear.

 

[officer58]

But you'd think my old antenna wouldn't have worked either.

Thank you all for your help, I have some things to work on now, so I'll do that and get back with ya. Have a good day.

 

[tvengr]

If the problem started when you changed the antenna, it doesn't take a rocket scientist to figure out that the problem is associated with the new antenna. If the antenna has higher gain, the cell tower can overload your receiver and cause all kinds of intermod problems. You said that you used thread lock on the antenna elements. Did you use it on the coax connectors also? Loctite is electrically conductive If it gets between the shield and center conductor, that can kill your signal.

 

[K9KLC]

Thank you all for your help, I have some things to work on now, so I'll do that and get back with ya. Have a good day.

Please check back in and let us know what you find out! Good luck and be safe!

 

[kc2asb]

I agree with this, I think the cell tower is possibly causing your issues.

I agree, but it was not causing issues when he was using the old antenna. As suggested above, going back to the old antenna to see if the problem resolves itself is a good strategy.

 

[rbrtklamp2]

They sell filters for that, contact Par filters they are still in business I belive and they make custom filters to spec. Maybe he can whip up a cell freq filter. I have many many par filters for different places I visit where I have IDed interference.

 

[officer58]

Well, I took everything apart, cleaned all the contact areas, and reseated everything. That did make a difference, big difference. I don't get all the static I was getting. But I still don't receive State Police like I did. I think it's something to do with the programming. I use proscan and pull off of radio reference. Also had reset the scanner back to factory, so I feel like I'm missing something in the programming. Must be it.

 

[K9KLC]

Well, I took everything apart, cleaned all the contact areas, and reseated everything. That did make a difference, big difference. I don't get all the static I was getting. But I still don't receive State Police like I did. I think it's something to do with the programming. I use proscan and pull off of radio reference. Also had reset the scanner back to factory, so I feel like I'm missing something in the programming. Must be it.

Ok so now the plot thickens. What site on Starcom are you actually getting or trying to get? Did you add the ISP talk groups you were wanting for your district?

 

[rk911]

Sounds like simple cause and effect especially if the reception tanked right after the new antenna was put into service. EZ way to check...put the old anten a back in service and see what happens. If the problem persists then I'd suspect the coax, connector,or borh.

 

[ofd8001]

I'd suggest taking the scanner to some other location, not near something like a cell tower, use the stock antenna and see what happens.

That may help to differentiate between a scanner problem and an environment problem.

 

[officer58]

Still working on this, so verdict is still out.

 

[officer58]

Well, have an update. I moved the antenna farther away from the cell tower. That did help reception on local channels. And I was picking up from 60 miles away. But still no State Police . I reprogrammed and reprogrammed from Radio Reference several times and still nothing.
Tonight, I decided to scan the whole data base. And guess what, I started picking it up. Only leading to further puzzlement. As I suppose something in the programming. What I'm not sure. So that's where it stands, at least I know it's not the radio.

 

[tvengr]

But still no State Police

As I suppose something in the programming. What I'm not sure.

Please export and attach your favorites list file so we can take a look at it. Go to the File tab in Sentinel and click on Export to hpe file (Favorites List). You will need to zip the file to be able to attach it. Click on Attach files and open the zipped file. You can also attach your ProScan file.

 

[K9KLC]

Well, have an update. I moved the antenna farther away from the cell tower. That did help reception on local channels. And I was picking up from 60 miles away. But still no State Police . I reprogrammed and reprogrammed from Radio Reference several times and still nothing.
Tonight, I decided to scan the whole data base. And guess what, I started picking it up. Only leading to further puzzlement. As I suppose something in the programming. What I'm not sure. So that's where it stands, at least I know it's not the radio.

Sounds like a programming error then, the scanner is working, if it's not coming in when you are on your programmed stuff but on the whole data base, that doesn't leave much else.

 

[officer58]

Well I have an update finally.

 

[officer58]

I went back to a tram antenna, since that is what I was using prior to losing State Police and other freq. Also, I purchased a Whistler TRx 2 radio.
I had had one before and liked it. So I started picking up some of the things I hadn't like amateur radio, airports. But no state police. Last night I was listening and what pops on, State Police ISPERN. Loud and clear. I was very happy about that. But I have yet to hear State Police dispatch or anything from the field. So not sure if I should investigate the setting in ISPERN and see if it matches the others. And not sure if my diamond antenna was bad. So still have some investigating to do. And the other thought , maybe State Police just aren't transmitting like I think they should be. What I love about this hobby.

 

[Ubbe]

Use that variable attenuator, or if you have a 10dB fixed one, to find out if you have interference issues. Check the signal level in a frequency band with less risk of interference, maybe 400-425MHz and a transmitter that often transmit and then insert the attenuator and adjust so you get a 10dB lower signal. Then go to your 700-900MHz band and a steady transmission and check that you get a 10dB difference with and without the attenuator. If you get a 7dB or lower difference or 13dB or more then you have RF interference issues.

A discone have a 10dB attenuation built into its design compared to a standard vertical antenna element so that could be a reason to why you get better reception as any interfering signal are then below the level where it starts to de-sense the receiver.

By slowly changing the attenuation level you can find out how little is needed to stop the receiver from overloading but still have a good sensitivity.

/Ubbe