SDS100/SDS200: Questionable VHF/UHF sensitivity and upgrades

[Ubbe]

I have done service monitor checks and the bottom line is that the SDS100 meets published sensitivity on a bench check....
.... Reducing the gain to the point that overload would not be an issue would probably result in sensitivity specs that Uniden would be afraid to publish...

But Uniden have never published any guaranteed specs? And probably rightfully so with an SDR receiver that can be tuned to any gain settings to adapt to users feedback after the release. A test bench measurement in a controlled RF enviroment, no interfering RF at all, will not give any meaningful results. Only real user experiance will have any bearing or advanced measurements using several RF sources to discover its dynamic range and intermodulation problems that all $5 SDR receiver chips has.

Unidens says they've received less official complaints from SDS100 owners than for their other scanners but as it is a complex scanner most people with problems don't want to take the risk of being seen as fools if their complaints turns out to be user error. So they stick with it and hope that there's a setting they have to learn about or that Uniden at some point makes some magic tricks that transform the SDR chip into a quality receiver far beyond its technical specifications.

In one of Upmans posts he recommends the BCD436HP over the SDS100 if you don't experiance simulcast issues, and he should know what to expect in current and future states from both models.

/Ubbe

 

[coolderb]

My original "first Run" SDS100 had the same VHF/UHF issues, analog or digital. However, after a couple lengthy trips to Uniden Repair, I was given a factory refurbished unit as a replacement to my original. The factory refurb unit exhibits none of the original VHF/UHF issues.The refurb unit is actually better than my x36 scanners.

I do have both DMR and NXDN upgrades and they are flawless on the "New" refurb unit.

"..after a couple of lengthy trips"

Whew, I hope mine is fixed after only 1 lengthy trip. I sent it in for repair a month ago yet the status has not been updated beyond "received".

Uniden's repair facility must be overloaded

 

[mapper65]

I posted a similar question a few weeks ago while entertaining the idea of buying an SDS100. I had heard & read that some people were having issues on UHF. A friend of mine has two 436’s. One of which had to have the capacitor added after the fact and the second was one that was built with the missing capacitor. He is also interested in the SDS100 also but after hearing what I also heard he said he wanted to wait and see how this supposed problem on UHF worked out.

I decided to order an SDS100 from Bearcat Warehouse. When it arrived I did some side by side tests with my BC220XLT and the SDS100 outperformed the BC220XLT in every test. I took the SDS100 over to my firend’s house. Now I realize that this was by no means a scientific test but three is an old UHFrepeater in the fringe coverage area from his location that is still putting out a weak signal. With his original 436 he was not able to hear this repeater. Once the capacitor was installed you could hear ipthe repeater but it was very weak as expected The second 436 that came with the capacitor already installed worked fine but obviously the signal was still weak. My SDS100 picked up this signal maybe just a little stronger than either of his 436’s so we suspect the SDS100 is at least as good as the 436 which works very well on UHF/VHF.

 

[hiegtx]

I posted a similar question a few weeks ago while entertaining the idea of buying an SDS100. I had heard & read that some people were having issues on UHF. A friend of mine has two 436’s. One of which had to have the capacitor added after the fact and the second was one that was built with the missing capacitor. He is also interested in the SDS100 also but after hearing what I also heard he said he wanted to wait and see how this supposed problem on UHF worked out.

I decided to order an SDS100 from Bearcat Warehouse. When it arrived I did some side by side tests with my BC220XLT and the SDS100 outperformed the BC220XLT in every test. I took the SDS100 over to my firend’s house. Now I realize that this was by no means a scientific test but three is an old UHFrepeater in the fringe coverage area from his location that is still putting out a weak signal. With his original 436 he was not able to hear this repeater. Once the capacitor was installed you could hear ipthe repeater but it was very weak as expected The second 436 that came with the capacitor already installed worked fine but obviously the signal was still weak. My SDS100 picked up this signal maybe just a little stronger than either of his 436’s so we suspect the SDS100 is at least as good as the 436 which works very well on UHF/VHF.

Your experience matches what I've said before. While some very credible members here on the forums have reported scattered Vhf/Uhf reception issues, others have noted none, as your test seems to show. I have two 436HPs, a 536HP, and an SDS100. For the systems that I specifically monitor, there is no noticeable lack of sensitivity in the SDS100.

Just looking at the numerous comments, pro and con, by experienced users, it appears, at least by what I've seen, that there may not be a specific problem with the SDS100, but that is more variance in sensitivity and performance between individual units than I would normally expect. That is somewhat verified with units that had been sent for repair, due to sensitivity among other things, and when returned, performance was noted as much improved.

 

[milcom_chaser]

But Uniden have never published any guaranteed specs? And probably rightfully so with an SDR receiver that can be tuned to any gain settings to adapt to users feedback after the release. A test bench measurement in a controlled RF enviroment, no interfering RF at all, will not give any meaningful results. Only real user experiance will have any bearing or advanced measurements using several RF sources to discover its dynamic range and intermodulation problems that all $5 SDR receiver chips has.

Unidens says they've received less official complaints from SDS100 owners than for their other scanners but as it is a complex scanner most people with problems don't want to take the risk of being seen as fools if their complaints turns out to be user error. So they stick with it and hope that there's a setting they have to learn about or that Uniden at some point makes some magic tricks that transform the SDR chip into a quality receiver far beyond its technical specifications.

In one of Upmans posts he recommends the BCD436HP over the SDS100 if you don't experiance simulcast issues, and he should know what to expect in current and future states from both models.

/Ubbe

"But Uniden have never published any guaranteed specs?"

Not guaranteed, but a baseline performance from lab measurement.

 

[GadgetGeek]

VHF & UHF works great on my new sds100.

In fact I noticed last night my sds100 was picking up a low VHF signal that my Home Patrol 1 completely missed.

 

[Markscan]

VHF & UHF works great on my new sds100.

In fact I noticed last night my sds100 was picking up a low VHF signal that my Home Patrol 1 completely missed.

I have a Home Patrol 2 using a rooftop antenna, and my SDS100 was receiving a VHF transmission that the HP2 missed. I think it’s the luck of the draw with these radios.


Sent from my iPad using Tapatalk

 

[bravo14]

I have to say this on the sds100. All this is in search mode. I have alot of interference in the apartment. UHF I notice when EMS pages a unit and talks the SDS100 on the freq should be normal but it has a mirror image on another uhf freq. Now I notice another UHF freq is doing the samething with a cap+ system that freq is not even listed and picks up 1-2 bars. When I'm listening to the 800 analog system the audio will be analog than the audio quits and comes back I don't know what is up with that. They are putting up a new p25 800 system seems same freqs. I do have all audio set as analog.

 

[TailGator911]

I have compared my SDS100 vhf/uhf reception alongside both my TRX-1 and BC125AT and it is spot on. I am picking up clear vhf airport tower transmissions from 25 miles away with the Remtronix duck antenna. Even better when using my rooftop directional yagi and/or Diamond discone. I recently logged a uhf transmission from a security company in Centerville on the SDS100, quite a few miles away from me here in Fairborn. I am inclined to believe that any vhf/uhf reception issues with the SDS100 may not be operator error, but occurring only with some production runs of the radio. I am glad to see more positive results being posted by other SDS100 satisfied owners.

JD
kf4anc

 

[UnidenSupport]

"..after a couple of lengthy trips"

Whew, I hope mine is fixed after only 1 lengthy trip. I sent it in for repair a month ago yet the status has not been updated beyond "received".

Uniden's repair facility must be overloaded

How is your unit's performance after getting it back?

 

[yugps]

SDS100 at 360-380Mhz, the sensitivity is not as good as BCD436