SDS200 Front end overload again

BruceMN

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Joined
Oct 25, 2004
Messages
14
Location
Duluth, Minnesota
#21
I had signal desense problems with my GRE PSR-600 while using an outside antenna. I could not receive very much of anything with or without the attenuator activated until I tried an old radio shack FM broadcast filter (88-108 MHz). After I installed that filter everything came to life on the scanner including the 800 MHz P25 in MN and VHF P25 system in WI.
 

sparklehorse

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May 15, 2003
Messages
921
Location
Portland, Oregon
#22
SDR chips do not have the best RF performance needed to let them be used in a high end scanner without problems popping up in a thougher RF enviroment. Upman ones stated that if you do not suffer from simulcast issues you're probably better off with a BCD436 than a SDS100. Probably the same will apply to BCD536/SDS200.

/Ubbe
You know, I absolutely agree. Every SDR radio I’ve tried has had overload issues. Until I got the Anytone 868. That radio is the best analog VHF/UHF receiver I’ve ever owned. It’s not great as a scanner as it will only scan 50 channels at a time, and scans them at a painfully slow pace. But man it can pull things out of the mud my other radios just can’t. And it does so hooked up directly to my rooftop ST2 antenna. Most of my other radios, including the 536, need a whole string of inline Par filters (FM, TV, Pager) to function properly at VHF-Hi, as I’ve got a huge FM broadcast tower with 9 stations a mile away, a pager tower a mile away, and also three cell towers a half mile away. So the 868 has proven to me that a receiver doesn’t have to be superhet to perform well in a challenging RF environment. I’m hoping the SDS200 will prove to be just as good. Will know tomorrow when mine arrives.

.
 

epilab

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Joined
Jul 29, 2007
Messages
59
Location
Mass
#23
OK guys... got a question concerning this overload issue. there is offered a ATT-20 Variable Attenuator with BNC connections. any thought on this as a solution. And the specs include the following Or am I just dumbing down the reception and the sensitivity will suffer

useable frequency range: 0,1 - 1000 MHz
attenuation: 0 to 20dB continuously variable
control: 3 turns of the knob for the range 0 to -20dB
insertion loss at 0dB stop: less than 0,2dB
no intermodulation - passive
input connector: BNC/f
output connector: BNC/m
input/output impedance: 75 Ohms
 
Joined
Dec 28, 2003
Messages
450
Location
Laurel Springs, NJ
#28
Well I brought the SDS200 into my lab at work and hooked it up. It is working like a champ on the New Jersey State Police 800 MHz Motorola trunk system that I can't receive at home. The closest Cell tower is about 1 mile away and a cell phone repeater about 1/4 mile away. The remainder of the close services are US Government VHF FM services with the closest repeater about 3/4 miles away. So the problem is the 2 close cell phone tower about 1500' from my location at home.

I guess I'll keep the SDS-200 because it works fine on my county's 700 MHz P.25 Phase II system. I also like all of the info that is in the display.
 

sparklehorse

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May 15, 2003
Messages
921
Location
Portland, Oregon
#29
Well I brought the SDS200 into my lab at work and hooked it up. It is working like a champ on the New Jersey State Police 800 MHz Motorola trunk system that I can't receive at home. The closest Cell tower is about 1 mile away and a cell phone repeater about 1/4 mile away. The remainder of the close services are US Government VHF FM services with the closest repeater about 3/4 miles away. So the problem is the 2 close cell phone tower about 1500' from my location at home.

I guess I'll keep the SDS-200 because it works fine on my county's 700 MHz P.25 Phase II system. I also like all of the info that is in the display.
Try that Yagi I linked to in post #20. Might be the best $16 you ever spent. I have three of those now and use them in different places for different things. Using one lets me monitor a small 800 MHz Smartzone system 45 miles away I couldn't previously receive even with a rooftop ST-2.

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