BCD436HP/BCD536HP: RF Performance Feedback on 436hp

[Ensnared]

Finally RF Sensitivity Measure

The owner's manual for the x36xt radios has the 436 Air Band sensitivity (12dB SINAD) Nominal at 0.3 of a micro volt, which is good as far as I can tell.

It would be helpful if others could check their air band sensitivity out to rule out your unit being bad or to confirm that the 436 has a problem with air band reception.

My 436 seems to do OK in air band but I seldom listen to air band so my evaluation may not be very dependable.

I've been sitting here trying to recall what specification measure used to tell me RF sensitivity. Thank you for mentioning micro volt reading.

Historically, RS has tended to make analog scanners with less sensitive receivers in order to avoid reception issues. For instance, my Uniden 245XLT was a fairly sensitive radio on analog VHF high and UHF. I don't remember if RS made an equivalent of this radio. But, I believe the Pro-90 was another one that was less sensitive than the Bearcats.

But, lately, I haven't seen measures of RF sensitivity on the spec sheets. I might be overlooking these.

When people are discussing the "subjective" account of radio reception, why don't they mention these numbers I wonder?

At present, I am getting ready to take the Uniden plunge. My bucks are going for the 436HP.

 

[Ensnared]

Side by side, Concur

These side by side tests are worthless IMHO.

Everyone knows that moving the antenna 1/2" can make the difference between receiving a signal and not.
For example, I can make youtube videos of the 436HP appearing to be completely deaf compared to an old PSR500 sitting beside it on the desk. Placing one scanner next to another can introduce more variables too such as cpu noise from one scanner degrading reception on the other.

There are just too many variables involved.

Now, if people started posting videos of two scanners connected to the same external antenna, via a good quality splitter and there was an obvious difference, that would be a more valid test.

Better yet, how about some real sensitivity measurements?

Yes, I could not agree with you more. What mystifies me are the ones who sit two scanners side-by-side and then let them scan the same area or system. When the radios key up, it is difficult to discern which one is receiving. Then, they make a You Tube video of such.

The audio sometimes sounds like an echo between the two radios. No, this style of radio review is confusing and quite annoying.

 

[UPMan]

Historically, RS has tended to make analog scanners with less sensitive receivers in order to avoid reception issues. For instance, my Uniden 245XLT was a fairly sensitive radio on analog VHF high and UHF. I don't remember if RS made an equivalent of this radio. But, I believe the Pro-90 was another one that was less sensitive than the Bearcats.

Actually, RS has never made any scanners. Until about 2007, Uniden made about 50% of their scanners and GRE made the other 50%. After 2007, GRE had 100% of RS brand.

 

[Ensnared]

Correction: Branded

Actually, RS has never made any scanners. Until about 2007, Uniden made about 50% of their scanners and GRE made the other 50%. After 2007, GRE had 100% of RS brand.

Thanks. I should have been more specific. However, when they have branded radios, they have generally been less sensitive on certain bands than their Bearcat counterparts. For instance, I believe there were RF sensitivity differences between the Bearcat 235 and Pro-90.

 

[UPMan]

The circuit designs were virtually identical. Uniden did not change specs between RS and Uniden models. Historically, Uniden models have had much higher selectivity and slightly lower sensitivity than GRE-produced models. Selectivity (the ability to reject adjacent or other in-band signals) and sensitivity are design tradeoffs. Increase the sensitivity and you tend to decrease the selectivity.

So, GRE has done better at pulling in weak signals, but on the other hand have horrible performance in high RF environments. Uniden does slightly worse with weak signals, but is much more bullet-proof in high RF situations.

 

[Ensnared]

Learning

The circuit designs were virtually identical. Uniden did not change specs between RS and Uniden models. Historically, Uniden models have had much higher selectivity and slightly lower sensitivity than GRE-produced models. Selectivity (the ability to reject adjacent or other in-band signals) and sensitivity are design tradeoffs. Increase the sensitivity and you tend to decrease the selectivity.

So, GRE has done better at pulling in weak signals, but on the other hand have horrible performance in high RF environments. Uniden does slightly worse with weak signals, but is much more bullet-proof in high RF situations.

The many variables involved in understanding these systems is for others, not me. I do remember selectivity. Wasn't this associated with intermod problems?

Well, as I stated, I am trying to learn the behavior of these animals. How they behave in certain environments is very helpful. I believe that the electronic engineers who design these radios have reasons for making them the way they do and it is not likely any degree of oversight on their end.

Yes, I want optimal performance in a RF dense environment such as a big city. I can contend with the distant signals just fine.

How many people have said to you, "I want you job?"

 

[UPMan]

I cannot disclose that number. I can say, however, that none of them actually knew what I did, else they would not have asked.

 

[Stevenme]

UPMan, since you have jumped into the fray, can you comment on the 436 vs 396 comparison? Does the 436 have a design goal to increase selectivity at the expense of sensitivity, or should the two radios be very close?

It's difficult to compare the stated sensitivity numbers since the 396 uses ranges and the 436 uses specific frequencies. If the 436/536 had multiple frequencies in the 396/996 range, I used the lowest (best). This may be slightly biased since I believe the 396/996 stated sensitivity is the worst in the range. I took the numbers from the 396/496 online Wiki, and the 436/536 manual. Here's a summary:

396XT 996XT 436HP 536HP 436/536 Freq 396/996 Range Mode
0.4μV 0.3μV 0.4 μV 0.4 μV 25 .005 Mhz 25—27.995 MHz AM
0.3μV 0.3μV 0.3 μV 0.2 μV 40 .840 Mhz 28—53.98 MHz NFM
0.5μV 0.5μV 0.7 μV 0.6 μV 54 .050 Mhz 54—71.95 MHz WFM
0.2μV 0.2μV 0.3 μV 0.2 μV 72 .515 Mhz 72—75.995 MHz FM
0.4μV 0.5μV 0.6 μV 0.6 μV 107 .100 Mhz 76—107.9 MHz FMB
0.3μV 0.3μV 0.4 μV 0.3 μV 127 .175 Mhz 108—136.9916 MHz AM
0.3μV 0.2μV 0.3 μV 0.2 μV 161 .985 Mhz 137—173.9875 MHz NFM
0.5μV 0.5μV 0.6 uV 0.6 uV 197 .450 Mhz 174—215.95 MHz WFM
0.3μV 0.3μV 0.3 uV 0.3 uV 216 .020 Mhz 216—224.98 MHz NFM
0.3μV 0.3μV 0.4 μV 0.3 μV 272 .950 Mhz 225—379.975 MHz AM
0.3μV 0.3μV 0.3 μV 0.3 μV 406 .875 Mhz 380—512 MHz NFM
0.3μV 0.3μV 0.3 μV 0.2 μV 857 .150 Mhz 758—960 MHz NFM
0.5μV 0.4μV 0.3 μV 0.3 μV 1299 .925 Mhz 1240—1300 MHz NFM

(Sorry for the formatting, it looks much better in my Excel spreadsheet than the RR post!)

As I have stated in a previous post, I would rather see a more granular attenuator than simply reducing sensitivity to prevent overload. I live in the suburbs but I still have difficulty receiving 800mhz sites with my 396. If the 436 is any less sensitive, it is useless to me even though it offers a lot of other features I'd like to have.

 

[AA6IO]

Just got an ICOM R20 today from someone to make some more comparisons.
Ran the weather stations in my area. 162.450 and 162.550 are loud no matter what I use.
The antenna used was a RS Center-Loaded Telescoping Whip Antenna on my 436HP, 396XT, and R20.
All 3 units of course pick up the loud Wx stations. But the ones that are 60 to 100 miles away, it is a different story. The 436HP won't hear any of the weaker ones in my back yard, the 396XT hears 3 stations faintly to clearly that my 436HP does not, and the R20 hears those 3 stations nice and clear, perhaps S3 to 4.
We have the LA Cities Analog/Digital group of stations (about 300) here in LA. Many of these are on the old VHF frequencies. Some are UHF, and very few are 800 (don't think there are any). When I scan this system with portable units, prefer the 396XT vs 436HP. The 396XT hears much more than the 436HP on high VHF. On UHF, more of a toss up, but even then, 396XT seems more sensitive.
I like the 436HP for digital decoding, but it is not as sensitive as the 396XT, the R20, and my PRO-196 on VHF, and in some cases on UHF.
With the 536HP vs 996XT don't notice much difference, but I am using good outside antennas.
When it comes to portable use and antennas, sad to say, the 436HP is the least sensitive of all on lower frequencies. This did not seem to be the case with the original firmware, but I have repeatedly posted on different threads that with firmware ver 1.03.00, my sensitivity dropped on the 436HP.
When I listen portable for louder traffic while walking, in car, etc. The 436HP does great. But when I want to listen to farther stations in Ventura and San Bernadino counties (probably 50 to 70 miles away), no question that I will go back to the 396XT for portable.
To my postings that the 436HP is least sensitive on VHF vs other units, I sometimes get the response, I must have something set up differently. No folks, my 436HP is less sensitive than other units. Love the many features of x36HPs, but sensitivity of the 436HP is not one of them.
Steve AA6IO

 

[Boatanchor]

We really need someone to put a 436HP scanner on a service monitor/signal generator and compare against a known working 396xt or similar, or at least find out what the 12dB Sinad point is..

We need uV or dBm figures to lay this issue to rest.

From what you are saying, you are seeing magnitudes of 10-20dB or more difference in sensitivity between the 436HP and the 396/R20 using the same antenna - Surely this can't be right..

If what you are saying is right, then the 436HP VHF sensitivity would be around 2uV for 12dB Sinad, compared to ~0.3uV for the 396XT and possibly around 0.25uV for the R20 (which is about what I would expect for the last two models).

No VHF receiver manufactured within that last 50 years has been that deaf

 

[sibbley]

I was listening to testing on the new Berks County, Pennsylvania TRS (Berks County Public Safety Radio System Trunking System, Berks County, Pennsylvania - Scanner Frequencies ) yesterday afternoon on my PSR-800. The 436HP was in the same room although about 6' away from the 800, and It didn't hear a thing. I tried moving the 436 around the room and nothing. The 800 was hearing the system loud and clear full bars no matter where I moved it.

That system is 2 counties away from me. But hell, I have trouble hearing my own county at times with the 436HP. Northampton County, Pennsylvania (PA) Scanner Frequencies and Radio Frequency Reference

The 396xt is much more sensitive than the 436 on VHF and UHF. I would love for someone to use testing equipment to prove or disprove this issue. I've been testing with different firmware versions, and every time I revert back the radio seems to get better, but you lose in other areas.

Firmware version 1.01.00 has the best reception and volume, but the P25 is degraded and the squelch tail is awful at times. But even back at 1.01.00, the 396xt is better.

 

[AuntEnvy]

I love that 800

I really want to like/purchase the new 36 but I can't imagine getting one at this point. I just can't figure out why uniden seem to have so many problems with their product etc., especially considering the technology appears to be there and that other companies have figured out how to make it work.

There must be some kind of patent on the technology...??

I'm telling you, my 800 seems to work the best for everything, overall.

Sure, HP1 has the ease of use for mobile app with the GPS functionality, and I give uniden much credit for that, and the 996xt has an advantage of some sort I suppose. The 197 is a good unit but lacks a few things as far as ease of use or features maybe, but if whistler makes that base/mobile model of the 800 AND a GPS feature it's going to be a big time winner all the way around! (provided it still performs the same of course)

 

[AA6IO]

I would be interested in seeing some test results as well. Don't get me wrong, I still think the 436HP is a decent scanner. Selectivity compared to the wideband R20 is much better, On the R20, hear FM stations that are loud at 400 Khz away from the center frequency. Uniden scanners, including 436HP, just pick them right out on a selectivity basis. But sensitivity, a different story with the 436HP, especially on VHF.
For listening in radio-dense Los Angeles, the 436HP does very nicely. But I am a DXer at heart from back 52 years ago as a teenager who fell in love with amateur radio when I heard people talking from Europe and Africa. Even though I really don't do much of that now, I am always pushing all my radios to see what I can get out of them. So for the scanners, I mess around with Ventura, San Bernardino, and Northern San Diego County from here in LA Basin.
The 396XT hears stuff that the 436HP won't. I don't know if its 2dB or 4dB or 8dB or whatever, but if its at the noise level or a hair above, I'll will hear it. For this sort of scan DXing, I leave the squelch open and manually tune known frequencies.
I really hope this is a firmware issue, because in most other respects, the 436HP is pretty good.
Steve AA6IO

 

[kc5igh]

Mine, too!

Hello ssmhermanmd, et al:

Your experiences with the BCD436HP precisely mirror my own regarding sensitivity.

I wish I could remember how the current firmware version (1.03) in my radio compared to the original firmware in terms of sensitivity. All I remember at this point is that a local EDACS system I was focused on trying to monitor at the time was coming in very weak, and it was getting hung up on the EDACS "scannerbuster" beeps at the end of almost every transmission. The new firmware seemed to cut back on those end-of-transmission beeps somewhat, but they're still there to varying degrees, depending on how close to the transmitter I am (and therefore how strong the signals are).

I would be incredibly relieved to know that the 436's sensitivity issues are related to its firmware. That might mean there's hope for improvement and that I haven't actually spent more than $500 on a nice-looking paperweight.

The 436 is a pretty good performer when it comes to selectivity in strong digital signal environments, but as has been noted by other owners time and again, it's nearly or entirely deaf in weak-signal environments compared to other radios in identical locations with comparable or identical antennas.

"Boatanchor" makes an interesting observation about no recently manufactured receivers being this deaf, but there are too many of us having similar experiences with the 436 to chalk it up to imagination and subjective interpretations of rf performance. As Boatanchor's signature line says "What can go wrong will go wrong," and that seems to be the case with Uniden's latest release.

Speaking of Uniden, is a firmware upgrade for the 436 hung up on the 536's wi-fi dongle issue? It would be nice to know . . .

-Johnnie

 

[AA6IO]

Johnnie et al.
Just saw your posting above a few minutes ago. Meanwhile, for the last couple of hours before I saw it, I again did the testing at VHF frequencies between the 396XT, 436HP, and R20. This time from within my patio, where I normally get pretty good reception. I would say at least 4 to 8 dB difference, depending on the station. The 396XT actually compares favorably with the R20 on sensitivity, and I am satisified with both. The 436HP, much less sensitive.
Then, I went to our Los Angeles Sheriff Department. Ran the 396XT vs 436HP both with Diamond RH77CA antennas. This is a 480 Mhz system. In this comparison, across the board, the 396XT read at least 1 bar higher than 436HP. This went on for about 30 mins.
Then, I went to Vernon PD (LA County) which is on 158.7450 Mhz. This is a relatively weak signal at my location, but perfectly readable (on the 396XT and R20). Left all 3 units on with RS coil loaded antennas (3 at same time). Vernon PD was busy with some thefts, so there was a good amount of chatter (this is analog FM). Heard everything fine, not loud, about 1 bar on 396XT, maybe S1 or 2 on R20, and nothing, I mean absolutely zero (squelch off on all units during test). on the 436HP.

This 436HP problem is really disappointing, and frankly, shocking to me. On the weak weather stations I referred to in #33 in this thread, not only do my 396XT and the R20 I have borrowed hear the weaker ones, I even here it with the same antenna using my FunCubeDongle and SDR-Sharp.
Boatanchor suggests that someone do some formal testing. I don't have that kind of equipment.
I have a better idea: Why not have Uniden run some testing on 436HP with ver. 1.03.00 vs the 396XT at these frequencies in question. Let their engineers deal with this issue.
In all the "Should I buy the 396XT or 436HP comments in the last few months, I have answered the 436HP. But now that I have had the 436HP for several months and am putting it to use on some lower frequencies to hear some weaker stuff, this sensitivity issue is really the pits. Let the Uniden engineers do the comparisons, and fix this issue (if they can).
Unless someone wants to listen to Phase 2, I would now recommend the 396XT until this problem, and the flimsy SDR card holder problem is resolved. I'm lucky that I can afford both the 396XT and 436HP, and several other rigs. But if I had to sell my 396XT and use the money to buy this 436HP, I would really not be a happy camper. In fact, right now with regard to the 436HP, I am not a happy camper.
Steve AA6IO

 

[AA6IO]

One more comment: These comments on this thread pretty much mirror the thread entitled "BCD436HP first-month performance assessment." The last post on that thread was about the end of April. What's different, nothing, and that is exactly the problem. We are now going to be celebrating the 4th of July, almost 8 months since these new Unidens were announced, and about 5 to 6 months since they have been available. Why are we still waiting for these updates. This just does not seem like the Uniden brand that I have known for many years.
Steve AA6IO

 

[kc5igh]

Hi, Steve.

No, this isn't the Uniden company or product line that I'd come to rely on over the years, either.

I launched that first-month performance assessment thread back on March 12, and I've been waiting ever since to conduct a better assessment once Uniden provided the long-promised firmware upgrade.

I would like to update one item I noted in my original assessment regarding the BCD436HP's performance on a nearby P25 trunked system that's being developed from an existing EDACS system. I stated back in March that the 436 was only receiving 40% or 50% of the digital traffic on the new system compared to my other receivers. Well, it turns out that the 436 is so sensitive to the digital signals on this new system that it is undergoing front-end overload. Turning on the 436's attenuator for this system dramatically improved reception and made its digital performance comparable to the other radios.

That, to me, is an interesting turn of events that I'd like to understand better than I do. I've spent a lot of time complaining about the 436's lack of sensitivity to analog signals only to find out that it seems to be extremely sensitive to digital signals. I don't know if, or to what extent, this might be attributable to the radio's firmware, but I for one would appreciate a better balance between the two--something comparable to what I'm currently enjoying in the BCD396T, BCD396XT, PSR-500, PSR-800, and PRO-106.

Uniden accomplished this before with the x96 radios, and hopefully they can achieve it again in the 436!

Thanks for listening.

-Johnnie

 

[FeedForward]

I am in disagreement with the concept that good receiver selectivity implies that front end sensitivity must be compromised. Front end sensitivity is not only a result of good design techniques but also to some extent depends upon on the statistical chances of pulling an excellent part off a reel during the manufacturing process. Also, the design team must occasionally defer to requests from the accounting department to use a less expensive part that will perform almost a well.

The RF front end and specifically the first RF amplifier sets the noise figure of the entire unit. High level signals do create problems for a sensitive front end, but the application of RF AGC will eliminate most of these problems. Dealing with powerful adjacent signals, capture effect and out of band signals are really the job of the IF section, and these adverse effects have very little to do with the sensitivity of the front end.

That is why the big bucks still go to providing an excellent IF passband. Many HF receivers - for example - now employ tunable digital passband filtering, notch filters, impulse noise blankers and so on. A quick look through the HF receiver roster shows that you pay a hundred dollars or more for an improved narrow passband mechanical or digital filter for your $1000.00 receiver. In short, I don't see sensitivity and selectivity as trade-offs. But as usual it isn't that simple.

FF

 

[Boatanchor]

One of the main problems with these scanners is the IMD interference generated in the RF amplifier/mixer stages. RF AGC has a role to play, but only if the desired signal needs to be reduced in level. RF AGC only looks at the signal level of the carrier that you are tuned to, not all of the multiple unwanted signals that are fed through the 100Mhz wide front end band-pass filter and then applied to the poor little RF amplifier and first mixer.

RF AGC for instance, does not register the multiple > -20dBm signals being applied to the RF amplifier from the cell tower just down the road, or the local Taxi transmitter two doors down, or in the GRE/Whistler case, the 10KW FM broadcast tower on the next hill.

No, the main problem with all of these scanners is the wide nature of the front end bandpass filters and the poor IP3 performance of the first active (RF amplifier & mixer) sections.

'Real' (Motorola/ Harris / Tait etc) radios employ actively tuned (varicap tuned) front end bandpass filters that may have a bandwidth of less than 2Mhz followed by high IP3 active stages which reduce the likelihood of IMD interference and blocking from strong in-band signals.

High IP3 active stages like RF amplifiers, consume a lot of power. A high IP3 LNA could consume 1-1.5 watts of power on it's own so, obviously, you can't incorporate a high IP3 front end in a handheld scanner if you want the batteries to last more than an hour or so on standby

But, manufacturers could employ high IP3 amplifiers in their mobile/base scanners at a minimal cost of maybe $1 or $2 extra for the part.

Tracking front ends would really help and would not add significantly to the power consumption, but the scan rate of a modern scanner may be too high to incorporate this feature.

There are things that could be done to improve scanner RF performance. It just needs the manufacturers to recognize that their scanners are not being used in the same RF environments that scanners were used in 20 or 30 years ago. The bands are becoming more congested and signal levels are increasing. Taking the lazy way out and using 100Mhz wide bandpass/window filters followed by poor IP3 performance components in the front end and sub-standard IF filtering needs to be addressed. There is no point investing huge sums of money in software bells and whistles if you don't get the basics right!

Otherwise, you end up in a situation where you promise the earth and deliver..... Umm..

 

[SCPD]

RF

I noticed a significant improvement in the amount of channels as far as weather and more "hits" when I diverted the 436HP back to the older 1.01.00 firmware.Air band and VHF pick up better.How odd.....I even switched back to the new firmware to test it.I dont want to use older firmware but the sensitivity is better or something is different!