BCD396XT/BCD996XT: Bring your 3/996XT into the 21st century :)

[JamesO]

Swapped the filter out in my HP1E yesterday.

Have not had a chance to really make a determination about performance, but I doubt it actually degraded anything. Expect that it should offer some improvements overall.

 

[molay]

After work up the courage to take the soldering iron finished installing the new filter in my BCT15.
I have not had much time to check for changes, but does not seem to have any detrimental effect. Reception in air band seems to have improved. Thanks to Boatanchor , sodjan et all. Is nice to see the mods and DIY scene remains alive.

 

[Boatanchor]

After work up the courage and take the soldering iron finished installing the new filter in my BCT15.
I have not had much time to check for changes, but does not seem to have any detrimental effect. Reception in air band seems to have improved. Thanks to Boatanchor , sodjan et all. Is nice to see the mods and DIY scene remains alive.

Nice work there molay

NFM and AM performance should definitely improve.
I have noticed the occasional very minor distortion on certain weak and 'loud' (deviating over +-5Khz) FM signals after replacing the filter, but it is not really an issue since these are few and far between and most of the activity here is NFM or P25 anyway.

How do you find the squelch setting now?
Did you need to turn it up to 7-10, instead of 2-3?

B

 

[mrkelso]

Anyone have an extra to sell me ? I have a friend that will mod my machine if i can find a 50G

 

[minasha]

Murata 50G filter

Hello,
If anyone has an extra 50G Murata filter please let me know if I can buy it from you.
I would like to use it in my bcd396xt.
I would also do a barter with anyone who needs a filter installed, I will install it for you in exchange for
one in return. I am a bench technician with over 40 years experience on circuit boards.

 

[kellykeeton]

I have responded to all PM for my extras, all spoken for now

 

[XTS3000]

Performed the filter mod on my HP-1 (Extreme upgrade). I am both happy and shocked at the improvement on ALL bands.

VHF / UHF conventional frequencies with PL. Less 'hiss' on all narrowband freqs. This just by itself is worth the filter upgrade. It got rid of the super annoying hiss. Sensitivity has seemed to improve as well. Weather band audio seems to be a bit 'pinched' up, but perfectly audible with no distortion. I still need to do some SAME decoding tests later to make sure it will still decode weather alerts 1050Hz and FIPS. I suspect it will pass.

Airband seems to work just fine as well. I don't normally listen to airband, but spent 6 hours testing it on airband. I can not see any negative side effects. Purchased the ACARS app for iPhone and it decoded the data fine.

EDACS Standard (wideband) works perfect on the one system local here. My RF signal on this EDACS system is weak (0-2 bars on the signal meter). Went to advanced extreme features and analyzed this system. With the weak signal of one sliver of a red bar for signal strength, the quality is 75-100%. Listening with a 436HP and the HP-1, I hear no "holes" in decoding the wideband system with the new filter installed.

P25 (3600 TRS mixed mode) simulcast system. I'm right between two towers. One is 4 miles north, other tower is 5 miles south. Decoding appears to have improved as well. It certainly did not get worse.

In conclusion, this filter mod makes the HP-1 worth owing now. Before I disliked it mainly for its 'hissy' audio. I looked and had not updated it for close to 2 years. Now it will be part of my normal scanner setup. Cheers to the OP for discovering and sharing this awesome mod. Thank you.

 

[JamesO]

Also got around to updating my HP1E last week as well.

Might have made a mistake on doing the filter install and latest firmware update at the same time, so not 100% what overall improvement the narrower filter may have had.

But I see no negative side effects since putting the narrow filter in my HP1E.

HP1E RF board is a bit harder to reach than the 396XT, on the far bottom of the board stack, but not too bad overall to access. Need to remove antenna connector nut and a few more screws to pull RF board.

For anyone that is interested, attached picture of RF board before I swapped in the narrow IF filter.

 

[tumegpc]

Filter mod for 536HP ?

Does the 536HP use the 50E filter ? If so, I wonder if doing 50G filter mod would help on the analog side ?

 

[ka3nxn]

From what I have heard the new 436 & 536 scanners are fine and don't need the mod.

 

[ka3nxn]

I have a few available

Gang,

I have I believe 4 spares available for sale, or I can do the mod for you.

Send me an email to ka3nxn(at)comcast.net

Jaime

 

[Boatanchor]

From what I have heard the new 436 & 536 scanners are fine and don't need the mod.

The x36HP scanners already have this filter and a standard FM (50E) filter installed.
What is not known (yet), is whether P25 is actually fed through the narrow filter or if it is fed through the wider FM filter.

It has been reported in the past that even though the GRE PSR-5/600 scanners had the narrow filter, when the P25 mode was selected, the IF was routed through the wider FM filter regardless of the NFM/FM setting.

 

[WD4CQ]

I have (1) BC996XT, (1) BC396XT, (2) HomePatrol-1 Scanners....

I would like to know if anyone has (4) or more filters for sale??

I'd take (6) filters, so I would have 2 as spares.

-------------------------

Danny KJ4FH
BC536HP, HomePatrol-1, BCD996XT, BCD396XT, BC785D, Many Others....

 

[wx5uif]

I've had mine installed for nearly two weeks now.

I have bct15, bcd996t and bcd996xt. All 3 sound better and no issues with squelch settings as mentioned earlier.

 

[WD4CQ]

Will this Filter help on a True P25 Phase-1 System such as:

New Bern Public Safety (Project 25) System Trunking System, New Bern, North Carolina - Scanner Frequencies

I've contacted both Mouser & Digikey but no stock, and orders must be 200 (Qty) or more...

Anyone have a few to spare? I would like to try this Mod.

 

[Mike_G_D]

The x36HP scanners already have this filter and a standard FM (50E) filter installed.
What is not known (yet), is whether P25 is actually fed through the narrow filter or if it is fed through the wider FM filter.

It has been reported in the past that even though the GRE PSR-5/600 scanners had the narrow filter, when the P25 mode was selected, the IF was routed through the wider FM filter regardless of the NFM/FM setting.

Boatanchor,

If someone has a 436 or 536 and is ok with opening it up and gaining access to the inside and can get access to either IF filter, a simple test might be worthwhile. Using ideally a spectrum analyzer but, at 450KHz, even an oscilloscope looking at the time domain signal could work, one could look at the output of each filter while monitoring a P25 signal and see which one is "switched in" assuming the "switch" is before the input to the filters. If you can select the bandwidth even in P25 mode, then one could make that change operationally on the scanner and see if it changes also in the circuit. This should be tested in both conventional and trunked modes the later of which might be more problematic, of course.

If a signal is seen at the output of both filters at all times of nearly equal level, then it is unfortunately likely that the switching follows the output of the filters and must be found further down the line (though I would think this unlikely, it is still a possibility).

-Mike

 

[Boatanchor]

Boatanchor,

If someone has a 436 or 536 and is ok with opening it up and gaining access to the inside and can get access to either IF filter, a simple test might be worthwhile. Using ideally a spectrum analyzer but, at 450KHz, even an oscilloscope looking at the time domain signal could work, one could look at the output of each filter while monitoring a P25 signal and see which one is "switched in" assuming the "switch" is before the input to the filters. If you can select the bandwidth even in P25 mode, then one could make that change operationally on the scanner and see if it changes also in the circuit. This should be tested in both conventional and trunked modes the later of which might be more problematic, of course.

If a signal is seen at the output of both filters at all times of nearly equal level, then it is unfortunately likely that the switching follows the output of the filters and must be found further down the line (though I would think this unlikely, it is still a possibility).

-Mike

Hi Mike,

Yes, it wouldn't be hard to check with a Spectrum Analyser.
If it is found that P25 is fed through the wider filter, it would theoretically have a negative impact on adjacent channel rejection when in the digital mode.

I'd be surprised if Uniden would have gone down this track for one simple reason though.

Early on, when there was discussion about unreliable digital decoding on some systems, UPMAN suggested that users change from the default NFM to FM mode and then report back here whether digital decode had improved or not. Some users reported improvement, while others reported a degradation.
If the FM/NFM mode made no difference to the IF path in digital mode, presumably, there would be no point in suggesting this course of action and there would be no difference in decoding performance??

Of course I could be wrong, it is possible that an error (decision?) was made to default the routing of digital modes through the wider filter regardless of the NFM/FM mode.

The placebo effect of changing modes cannot be ruled out either

 

[Mike_G_D]

Hi Mike,

Yes, it wouldn't be hard to check with a Spectrum Analyser.
If it is found that P25 is fed through the wider filter, it would theoretically have a negative impact on adjacent channel rejection when in the digital mode.

I'd be surprised if Uniden would have gone down this track for one simple reason though.

Early on, when there was discussion about unreliable digital decoding on some systems, UPMAN suggested that users change from the default NFM to FM mode and then report back here whether digital decode had improved or not. Some users reported improvement, while others reported a degradation.
If the FM/NFM mode made no difference to the IF path in digital mode, presumably, there would be no point in suggesting this course of action and there would be no difference in decoding performance??

Of course I could be wrong, it is possible that an error (decision?) was made to default the routing of digital modes through the wider filter regardless of the NFM/FM mode.

The placebo effect of changing modes cannot be ruled out either

No, I don't think it was a "placebo effect". I am pretty sure they are using that narrow filter as selected by the user (in the new x36 models). But it would be relatively simple to confirm as I suggested. An o'scope is really all you need at that frequency. The only other way the NFM setting would have any effect is through the audio compensation as was done on the older x96 and 15 models. But, given the dramatic nature of the effects, I really think they are using a real switchable filter selection. Given what I was seeing as folks were describing what kind of problems they were having and a few scattered posts describing changes as the database was upgraded as well as the firmware it led me to the conclusion that it was likely that Uniden did finally include a real filter change in the new models and that may have an effect as described. The database and firmware are really problematic in this. Unfortunately, the RR database hasn't really fully caught on concerning the selection of "NFM" (+/-2.5KHz deviation) versus "FM" (+/-5KHz deviation) for both conventional and trunked systems and the "Auto" selections are still based on flawed data and a poor or incomplete understanding of the US FM LMR deviation requirements relative to frequency (for example, +/-5KHz deviation allowed on 30MHz to 50MHz and above 512MHz except for some stuff in the 900MHz LMR band but +/-2.5KHz required for Part 90 services only between 138MHz and 512MHz therefor excluding things like Marine, GMRS, Ham, Remote Broadcast services, etc., though FRS and three of the five MURS frequencies have been required to use +/-2.5KHz deviation for some time now). For software/firmware developers that may not be native to the US these requirements can seem confusing and it does not surprise me that they have some difficulty getting the defaults in the firmware set correctly every time they make changes; that plus the RR database "FM" versus "NFM" records being "inconsistent" at best makes for the type of situation we have seen. This is why I made my initial suggestion to make that change manually early on (it was a guess on my part but I had already been curious if Uniden had added a real narrow filter selection and, if they had, given the issues with the firmware and database the results would be expected to be something like what I was reading about). Given Upman's subsequent request of users to make these manual filter selections (not to mention the many users reporting moderate to major changes in noted reception as a result of making said changes), it seems pretty likely that the P25 signals are indeed being routed through either filter as selected by the user either through software or manually unlike GRE's hampered approach.

Still, a real probe as a confirmation would "put the cap" on the idea.

-Mike

 

[Bote]

The only other way the NFM setting would have any effect is through the audio compensation as was done on the older x96 and 15 models.

Has this been confirmed?

I noted earlier in the thread how selecting NFM on my 996XT gives me "Heathkit" squelch, that is, very choppy squelch action with apparently no hysteresis. If the scanner is just increasing the audio gain then I wonder why the squelch behavior differs between NFM and FM? Ideas?

Also, please locate and use your Enter/Carriage Return key liberally. Our eyes will appreciate it greatly.

 

[Boatanchor]

Also, please locate and use your Enter/Carriage Return key liberally. Our eyes will appreciate it greatly.

Lol