SDS 200 Crackling Transmissions in the 450-485 mhz

[Nascar18]

I have a brand new SDS 200 and having really bad crackling after transmissions in the 450-485 mhz band. The scanner is connected to a Stridsberg multicoupler. I tried using the ATT on the UHF channels and finding some difference. Do I need to return the scanner to Uniden?

 

[MStep]

I have a brand new SDS 200 and having really bad crackling after transmissions in the 450-485 mhz band. The scanner is connected to a Stridsberg multicoupler. I tried using the ATT on the UHF channels and finding some difference. Do I need to return the scanner to Uniden?

Before considering any cold solder joint (or other technical) issue, I would disconnect the Stridsberg multicoupler and try the unit with just the included telescopic or connected directly to its own outdoor antenna, preferably with different cables.

If the unit still proves to be problematic, I would return it to the dealer from which it was purchased for a refund. It's a brand-new unit and should not have to go back to Uniden right out of the box.

 

[tvengr]

Are these conventional frequencies or trunked frequencies in a site? Are they analog or digital. Are some frequencies in that range working OK? Please let us know what you are trying to monitor.

 

[fxdscon]

I have a brand new SDS 200 and having really bad crackling

.
Can you post a recording of what you are hearing?

 

[Ubbe]

I have a brand new SDS 200 and having really bad crackling after transmissions in the 450-485 mhz band.

If it is a digital frequency then send it in to Uniden. If it's analog then there are different filter settings to try that will change a whole department of frequencies. You also have the IFX setting. If it changes when the attenuator are on then it's probably some sort of radiofrequency interference. If you monitor the same frequency with your 996 with open squelch, then you can't hear anything in the background that could interfere? Listen with the SDS200 with open squelch to hear the background noise and compare to 996. If all the filter and IFX are tested without making any difference then it can be some components failure, otherwise it's the RF environment that are too problematic for the SDS200 and could need some external filters, maybe a stop filter for a strong transmitter frequency.

/Ubbe

 

[Nascar18]

They are all conventional frequencies and analog. Anything trunked or digital is fine. I sent a new file without the ATT on and took the Stridsberg multicoupler off and it is better. I have the filters off. I did notice with my 996 some noise after transmissions on a few channels. Could the Stridsberg be overloading the SDS 200 in the UHF band?? I do have power going to the Stridsberg. Am I better off unplugging it?
It's my first experience with a Stridsberg multicoupler.

 

[Ubbe]

I have a Stridsberg but doesn't use it any more as it overloads too easily and its specification isn't that great compared to a $20 amp and $10 CATV splitter,, and then I live in a valley surrounded by hills and more or less only receive reflected radio signals.

Try at least the filter in SDS200 set to Normal and then Invert. Then stop scan on the problematic frequency and do Function+7 to toggle IFX on.

/Ubbe

 

[Whiskey3JMC]

I have a brand new SDS 200 and having really bad crackling after transmissions in the 450-485 mhz band. The scanner is connected to a Stridsberg multicoupler.

What do you have as an antenna at the other end of the multicoupler? No other bands aside from UHF affected?

 

[Nascar18]

Have been in contact with Joe Bearcat. He said it is a known issue with the SDS 200 will have a update out soon.

 

[RFI-EMI-GUY]

Are you nearby any TV stations that use the UHF 470 to 512 MHz band?

 

[Nascar18]

None.

 

[Nascar18]

I finally put a splitter before the Stridsberg multicoupler and the crackling problem is gone. Is the Stridsberg multicoupler overloading the SDS-200 in the 450- 485mhz band?

 

[Ubbe]

Bypass the Stridsberg by connecting the antenna coax directly to the scanner. Stridsberg have some 3dB gain on its outputs so it could be overloading the SDS200, or it could also be the Stridsberg in itself that overloads as it's performance specification isn't that great.

I always recommend a variable 0-20dB attenuator to be used and tried before and after the Stridsberg to see where it does most good when the signal are slightly attenuated. It works after the Stridsberg then it is only the scanner that overloads. There are $20 CATV attenuators with F connectors that you use with F-BNC adapters or pigtail coaxes with the different connectors at each end.

/Ubbe

 

[wtp]

try the stock antenna on the 200.

 

[ShawnInPaso]

I discovered this thread during a search because my brand new SD200 has the same issue as the OP describes. I also use a Stridsberg multicoupler which feeds three scanners, the SD200 and a pair of BCT15X radios. The 15X scanners have perfect audio on the same frequencies that the SD200 has serious crackling noises for strong signals (VHF/UHF NFM).

So I removed the multicoupler and connected the SD200 directly the the single coax coming from the antenna and seems the crackling has gone away, at least on one frequency. As per the Stridsberg specs, the coupler I have produces 2db gain. So, for example, if I receive a signal 2db stronger than the frequency I am listening to, it would seem logical that the crackling would manifest again?

Likewise, it would also be logical that I will not receive signals that my trusty 15X's will receive which would have a 2db advantage.

 

[ShawnInPaso]

Tried to edit this into my above post but ran out of time.

Edited to add:

Oops, so with further testing I still have the crackling without the multicoupler in line.

 

[Ubbe]

SDS scanner are extremely prone to receive interference from other frequencies, even down to -80dBm signal strengths can interfere. Try to change filter settings between Normal, Invert and if you see the frequency that crackle then enter that by Channel+frequency+Channel and if that didn't help then do Function+7 to toggle IFX on that channel and see if that helps and then also try to test the different filters again.

/Ubbe

 

[jtwalker]

I have two 200’s connected to a multi coupler and don’t have any issues with P25 trunked reception in 450mhz area. I don’t have a 15x on another port to make an even comparison.

 

[ShawnInPaso]

SDS scanner are extremely prone to receive interference from other frequencies, even down to -80dBm signal strengths can interfere. Try to change filter settings between Normal, Invert and if you see the frequency that crackle then enter that by Channel+frequency+Channel and if that didn't help then do Function+7 to toggle IFX on that channel and see if that helps and then also try to test the different filters again.

/Ubbe

Thanks for the recommendation. I just tried all of those various settings and still no joy.

 

[Nascar18]

Shawn,
I have been thinking of sending my SDS 200 in for service but will wait for the new update to see if it helps.