BCD436HP: RF Performance Feedback on 436hp

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Stevenme

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Even though this radio has been out a while, I have seen very few comments on the RF sensitivity of the 436hp. What I have seen seems to be somewhat negative when comparing it to the 396XT. I'm hoping there's someone out there that has both a 486 and 396 and can do a good comparison between the two radios on VHF, UHF, and 800. Find a weak analog signal in each of these bands and either using similar (stock) antennas or a common outdoor antenna (even better) note which one receives the signal with less noise. I'd trust my ear over the S-Meters since they may be calibrated very differently.

I currently have a 396XT and while I'm happy with the RF performance, for what I listen to I wouldn't be able to accept any less sensitivity from the 436. As long as it's at least as good (and hopefully better) I might be interested in pulling the trigger to get the new enhancements.
 
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sibbley

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In my area, I mostly listen to UHF conventional analog. There are some frequencies my county's system that don't come in real well depending on where I am at the time. My 396xt with a UHF 470-512 Laird two-way antenna, receives pretty clear even on the "bad" frequencies no matter where I am (almost as well as my Kenwood 3312). It's no so great with the factory antenna.

The 436, with the same Laird antenna, has a lot of noise. It drives me nuts. Some business frequencies are barely received compared to the 396xt. Our local Med-e-vac frequencies, forget it. I've all but given up on the 436 for conventional analog VHF and UHF in my area.

Now, trunked systems are another story. Analog or digital, are loud and clear. IMHO, the 436 is much better at decoding than the 396xt.

I've found that a good majority of my reception issues are found in my general area, the Lehigh Valley of Pennsylvania. If I'm out of the valley, the 436 performs very well.

It really depends on your area. I don't know exactly what causes the issues for me, cell towers, bad communication systems, or just being in a valley.
 

kb8rvp

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BCD436HP RF Performance Feedback on 436hp

In my area of Michigan listening to 800MHz APCO 25 phase 1 the 436HP is decoding better than my 396XT and it much better on my local simulcast system as well. They are about the same for me on analog.

Mike
 

troymail

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I've seen the 436/536 receive more distant 700 and 800 Mhz trunked activity than my PSR800 with the same RS 800 Mhz antenna. Receiving these distant signals is hit and miss many times and is affected by moving around the house (sometimes consistent reception and other times it comes and goes). However, my GREs are able to pick up a not so distant UHF trunked system fairly well while I had to drive almost on top of the UHF system to get the 436 to receive it - using several different antennas.

No personal experience but I've seen reports that some folks were having VHF reception problems on their x36.
 

airwolfbell222

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My Pro-164s, PSR-310 & AR8200mk3 leave my 436 in the dust when it comes to VHF/UHF airband. I've spent quite a bit of time testing in the airbands and even when I slap a Maldol AL-500H to the top of the 436, the other handhelds will pick up the signal with a stock antenna and the 436 is quiet which is similar to my BC125AT performance. The PSR-800 surprisingly out performed the 436 in the UHF airband.

On the other hand, the 436 seems to smoke my PSR-800 on 800mhz and I think that's probably where Uniden designed it to shine.
 

OregonScanner

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VHF reception is slightly better. With my 396XT I can barely pick up Washington State Patrol Vancouver dispatch which is VHF P25 about 70+ miles away from my location in Albany, Oregon. Transmissions are about 50% garbled on the XT. With the 436HP it comes in great...almost no garbles. Also, the local power company uses a VHF MPT-1327 trunked system. Their transmitter in the 161 MHz band is so powerful that on the XT radio, when I am within a few blocks of the trunked site I pickup MPT control channel data on all sorts of VHF freqs that don't have tones. The 436HP does a better job at fighting the intermod...it only breaks squelch on a few of the freqs that the XT has a problem with.

I noticed that VHF air band reception is less than the XT.

UHF and 700 MHz are the same just without P25 simulcast digital distortion....period...gone!

800MHz is about the same too.

I used to have a HomePatrol-1 and it has way better VHF reception than my XT or my 436HP but I just couldn't stand no keypad and simulcast distortion.
 

t0xPro-197

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i just got my new one wensday so far its out doing the 396 and pro-197 on both theres some noise on the 436 but it does reaily well id say was great buy ive got 2 beams hooked too my scanners can pickup bradly co tenn on good night here in cedartown ga and i got hills around me
 

Boatanchor

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Side by side tests

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?
 

kc5igh

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Sensitivity: 436HP vs. 396T

As has been noted above, sensitivity comparisons between two radios is subject to a lot of variables. It's always better to conduct sensitivity comparisons under controlled test conditions with some accurate (and expensive) test equipment, but most of us don't have the time or money for that.

However, it's been my consistent experience that my BCD436HP is much less sensitive in my listening environment (rural, mountainous) to weak analog signals (conventional and trunked) than are my BCD396T, BCD396XT, PSR-500, PSR-800, or PRO-106.

The 436 seems to be optimized for digital trunked systems in strong-signal environments. My 436 did a fine job recently of monitoring the Colorado digital trunked radio system in downtown Denver and was much less prone to front-end overload and intermod than was my PSR-800, which worked fine once I turned on its attenuator. Even in that environment, there was a marked difference (for the worse) with the 436's performance on analog systems (conventional and digital).

Back home in northern New Mexico, where I'm trying to monitor some relatively weak analog signals much of the time, the 436 can't hold a candle to the other radios mentioned above. The 436 does perform a little better on analog systems here with longer, high-gain flexible antennas, such as the Diamond RH951 or RH77, or hooked up to a decent external antenna, such as the Radio Shack discone, but those aren't always the best solutions, either.

I know these aren't objective, scientific observations, but I've done my best to make all these comparisons reasonably comparable when it comes to locations, antennas, and power sources (see my first-month performance report elsewhere in this section of the Uniden forums).

I'm hoping that some of these performance challenges (particularly for a local 400 MHz EDACS system) are due to firmware-driven decoding issues and that the long-promised firmware upgrade from Uniden may improve things.

Your performance will probably vary somewhat.

Best wishes,
-Johnnie
 

kc5igh

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correction

Apologies.

I meant to say "conventional and trunked" in the last line of the third paragraph in my message above.

Thanks,
-Johnnie
 

Stevenme

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Thanks Johnnie, this is great feedback. I agree it would be nice to get sensitivity numbers from test equipment, but it seems like most scanner users today don't have access to it. I think your weak signal conditions and wide variety of other radios is about the best we can hope for and in my mind is reasonable to be able to raise some concerns. The one question I have is this specific to certain samples, or across the board? That's a much tougher question to answer.

For me this is really a deal breaker. Right now in my area I don't need Phase II but I do need good sensitivity. The State Police sites that I monitor are weak at best and anything less than my 396XT would not be able to receive them (0, 1 or 2 bars of signal on the XT). I'm glad Uniden is working to increase selectivity and reduce strong signal interference, but this shouldn't be at the expense of sensitivity. I suppose firmware could resolve this assuming the RF hardware has the capability but is being limited by the firmware, but I suspect it's a hardware design decision.

To me this approach to the problem doesn't make sense. Why not add a better attenuator with several steps to allow the user to adjust the radio to the RF environment? Something like -10dB to -30dB in increments of 10. Just a thought.
 

SCPD

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Everything is great except

I think its all good except for Aircraft band,its fuzzy compared to a 396xt or a Gre 800when put side by side Not a dealbreaker but needs an up.
 

kc5igh

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Hello again, Stevenme.

That's a nice idea about a multi-step attenuator (provided, of course, that the radio has really good sensitivity to begin with). I'm sure it would add to the cost of the radio, but it might be worth the investment if you're trying to do some serious monitoring in an environment with a wide range of signal strengths.

I'm not sure what you meant when you asked if this was "specific to certain samples, or across the board"? If you meant sensitivity variations in specific frequency ranges, then I would say that my experience so far is that the BCD436HP seems to generally be most sensitive to digital signals in the frequency ranges I monitor (VHF-hi, UHF 400MHz, and UHF 800MHz). It's also been my experience that, when it comes to analog signals, the 436 seems to be most sensitive to 800 MHz signals, less sensitive to 400 MHz signals, and least sensitive to 155 MHz range signals.

Just last night I was using the 436 to monitor a nearby analog 400 MHz federal EDACS system. The signals coming through were strong enough to cause the 436 to stop the ID search and decode the talkgroup number, but the voice signals were weak and just barely discernible above background squelch. The 436 was running on AC power and using a Comet HT-55 flexible antenna at the time.

Frustrated, I turned off the 436 and replaced it with my trusty BCD396XT (also powered by AC and using an identical Comet HT-55 antenna). The difference was, as usual, incredible. The 396 (in exactly the same location where the 436 had been running) picked up the EDACS system "5 by 5" with nearly full-quieting on the audio! The 436 does seem to perform as well as my other radios on a local 800 MHz analog trunked system, but is nearly deaf compared to all my other radios on 400 MHz and 155 MHz analog systems.

If my experience is valid and you need good rf sensitivity in your listening environment, I'd stick with the 396. It doesn't have all the features that are packed into the 436, but rf performance will always trump features in my book.

Hope this helps.

-Johnnie
 

N9NRA

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I also ran some tests with this unit (436HP), and found it nearly deaf on airband, tested it against my `396XT, which has no problem recieving airband even with the stock antenna, the `436HP has problens untill i put a Watson super gainer on it, then things improved somewhat. Kinda technical question here, but i`m really curious to know, is the reciever in the `436HP a hardware one or is it somewhat SD (software defined)? Reason i ask is i got to thinkin` that the fix would be to add something via the firmware to "bump" up the recieve, or am i missing something here? If this is controlled via the firmware then it`s a easy fix, if not then a LOT of folks are gonna be sindin` back a LOT of scanners to have this fixed...can we say "LONG wait to get your (repaired) `436HP back"? I for one hope this sittuation improves, this unit has a lot of potential, it just needs some "spit & polish" that`s all :). N9NRA P.S. Also noticed this unit seems to have problens recieving distant stuff on VHF/UHF too, tested against my `396XT recieving the Lincoln County sheriff system (P25 conventional) and found that regardless of what entenna i had on it (Did see some improvement with the aforementioned Watson super gainer antenna however, just a smidgen better) the scanner was almost deaf, `396XT again had no trouble pulling in the same system. Intresting.
 

N0UDG

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I also ran some tests with this unit (436HP), and found it nearly deaf on airband, tested it against my `396XT, which has no problem recieving airband even with the stock antenna, the `436HP has problens untill i put a Watson super gainer on it, then things improved somewhat. Kinda technical question here, but i`m really curious to know, is the reciever in the `436HP a hardware one or is it somewhat SD (software defined)? Reason i ask is i got to thinkin` that the fix would be to add something via the firmware to "bump" up the recieve, or am i missing something here? If this is controlled via the firmware then it`s a easy fix, if not then a LOT of folks are gonna be sindin` back a LOT of scanners to have this fixed...can we say "LONG wait to get your (repaired) `436HP back"? I for one hope this sittuation improves, this unit has a lot of potential, it just needs some "spit & polish" that`s all :). N9NRA P.S. Also noticed this unit seems to have problens recieving distant stuff on VHF/UHF too, tested against my `396XT recieving the Lincoln County sheriff system (P25 conventional) and found that regardless of what entenna i had on it (Did see some improvement with the aforementioned Watson super gainer antenna however, just a smidgen better) the scanner was almost deaf, `396XT again had no trouble pulling in the same system. Intresting.
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.
 

N9NRA

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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.
It does fine on the close-in (meaning local, like, "in the city" stuff), but has a harder time with stuff that`s distant from where i am, which shouldn`t ve the case totally, as i`m five floors up in an apartment building, so i should be above the most of the avarage terrain, the only issues are two taller buildings across the street from me, and they`re not that big of an issue :). So this is really strange, that`s why i was alking of how the recieve was controlled, if this is partially defined in the firmware, than the fix is realatively easy, if not then get ready to see a TON of scanners goin` back to Uniden, and a LOT of folks rather cheezed off too, as the wait to get yer unit back from repair will be really LOOOONG :(. While terrain could have an effect here (and i`m sure it does, my 396XT has the usual time when listening to some stuff due to the buildings around me, but it`s not a real biggie), i still have a sneaky feeling there`s an issue with the recieve here. I would love to be proven wrong though :). N9NRA
 

Boatanchor

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Internally generated noise ?

We need a x36HP owner to put it on a calibrated signal generator/service monitor and check the sensitivity on various bands.

Personally, I'd be very surprised if there was any significant difference in sensitivity between the x96XT and the x36HP units. Uniden have been building relatively good scanner RF front ends for a long time now and you would think that they would have at least this part of the design pretty well nailed down by now.

The one big concern that I had when I started reading about poor VHF receive, was whether the units themselves are radiating broadband noise and suffering degraded reception from their own CPU/DSP's.
It would appear that most reports of poor, or degraded reception is from 436HP owners using the supplied or aftermarket rubber duck antennas attached directly to the unit. I haven't seen any reports complaining about sensitivity of the 536HP - this post should bring them out of the woodwork if there are :)

Anyway, if the 436HP is not shielded sufficiently, it is possible that broadband noise from the scanner's CPU/DSP may be interfering with received signals (when using an attached rubber duck antenna). This noise could conceivably mask weak Aircraft and other VHF signals by hiding them within the noise floor.
As the 436HP's case is plastic, it would offer no RF shielding and since the rubber duck antenna is only a couple of inches away from potential noise sources, it would not surprise me if this was the actual problem.

Connecting the scanner to a service monitor via shielded coax and testing the actual sensitivity would go a long way towards solving this riddle.
 

N9NRA

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We need a x36HP owner to put it on a calibrated signal generator/service monitor and check the sensitivity on various bands.

Personally, I'd be very surprised if there was any significant difference in sensitivity between the x96XT and the x36HP units. Uniden have been building relatively good scanner RF front ends for a long time now and you would think that they would have at least this part of the design pretty well nailed down by now.

The one big concern that I had when I started reading about poor VHF receive, was whether the units themselves are radiating broadband noise and suffering degraded reception from their own CPU/DSP's.
It would appear that most reports of poor, or degraded reception is from 436HP owners using the supplied or aftermarket rubber duck antennas attached directly to the unit. I haven't seen any reports complaining about sensitivity of the 536HP - this post should bring them out of the woodwork if there are :)

Anyway, if the 436HP is not shielded sufficiently, it is possible that broadband noise from the scanner's CPU/DSP may be interfering with received signals (when using an attached rubber duck antenna). This noise could conceivably mask weak Aircraft and other VHF signals by hiding them within the noise floor.
As the 436HP's case is plastic, it would offer no RF shielding and since the rubber duck antenna is only a couple of inches away from potential noise sources, it would not surprise me if this was the actual problem.

Connecting the scanner to a service monitor via shielded coax and testing the actual sensitivity would go a long way towards solving this riddle.
I can see where you`re comming from, but what of this, the `396XT is also a plastic case, and that one has no problem with weak signals on VHF/UHF and airband, and it has the same configuration for an antenna attached to the unit, it`s also only a couple inches from any potential noise sources, and as such should also cause degraded recieve, but i`ve never had a problem recieving with my `396XT, which makes me wonder just a smidgen. One way to see if the `436HP is putting out any kind of noise (broadband or other type of noise) would be to place a reciever next to the unit and let it scan and see if ya get any "birdies" or interference type signals, crude way to ferret this out, but it`d work in a pinch. I might actually try this once, just to see what happens, we`ll see, might be good for some experimentation and fun. N9NRA
 

Boatanchor

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A simple (better?) test is to do the following:

Place the 436 and the 396 (or any other handheld receiver) side by side on the desk.
Leave the 436 turned off for the time being.

Find a stable but weak aircraft or VHF signal on the 2nd receiver.
Then switch the 436hp on and see if there is any degradation of the weak signal on the 2nd receiver.
If the 436hp is generating RF noise, it should be obvious by an increase in noise on the 2nd receiver.
You could even try moving the 436 around the 2nd scanner antenna while it is receiving a weak signal but make sure you turn the 436 on and off to confirm whether it is cpu noise and not just near field effects on the antenna caused by the two units being in close proximity.

Basically, you are crudely checking for any increase in the noise floor of the 2nd receiver by turning the 436 on and off while the two units are very close together.

It's crude but surprisingly effective :)
 

Boatanchor

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A simple (better?) test is to do the following:

Place the 436 and the 396 (or any other handheld receiver) side by side on the desk.
Leave the 436 turned off for the time being.

Find a stable but weak aircraft or VHF signal on the 2nd receiver.
Then switch the 436hp on and see if there is any degradation of the weak signal on the 2nd receiver.
If the 436hp is generating RF noise, it should be obvious by an increase in noise on the 2nd receiver.
You could even try moving the 436 around the 2nd scanner antenna while it is receiving a weak signal but make sure you turn the 436 on and off to confirm whether it is cpu noise and not just near field effects on the antenna caused by the two units being in close proximity.

Basically, you are crudely checking for any increase in the noise floor of the 2nd receiver by turning the 436 on and off while the two units are very close together.

It's crude but surprisingly effective :)
 
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