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

[tumegpc]

Those of you who have done the HP-1's, how do you find the squelch setting after the mod?

After modding my 396XT and 996XT's, I find I need to turn the squelch up to around 10 or even a little higher, whereas pre-mod, the setting was typically 2 or 3.

Its not a problem, just an interesting side effect of reducing the filter bandwidth.

Hey Boatanchor,
I've been running my modded HP-1 squelch @ 2 for all bands. You are correct ,the 996XT does require a higher squelch setting. 7 seems to the sweet spot for all bands , if I'm just monitoring P25 I can take it down to 3.

 

[sodjan]

Hm, I wished I had another reel of these, would have been easy to sell...
I just checked and there are currently 24 shipments that has not got any
feedback yet, so they are on there way, I guess. Now, I do not know about
those who *have* got the filters but not left feedback, of course...

 

[Boatanchor]

Hm, I wished I had another reel of these, would have been easy to sell...
I just checked and there are currently 24 shipments that has not got any
feedback yet, so they are on there way, I guess. Now, I do not know about
those who *have* got the filters but not left feedback, of course...

Murphies Law

It's just Supply and demand..

I'm sure that Murata would be happy to sell a 1000pc reel of these filters for a buck each and then some enterprising ebay'er will cut them up and try and make a few bucks.

Then again, I really don't expect hundreds of scanner owners to suddenly want to modify their scanners overnight. It's just the oddballs (me include) who frequent these forums that would even consider taking the cover off their toy/s and tinkering with the innards

It would be a very game person to drop $1000 on a reel of filters when there is every likelihood that he/she will get stuck with $800 worth of product that he/she can't sell.

 

[awattam]

I want one....please..

If anybody has a spare one, I will gladly take one. Heck, I will even supply a return envelope with a stamp on it.

 

[Skypilot007]

I just did the mod to one of my 996XT scanners. I'm experiencing an adverse side effect as others have mention with the squelch. When I scan multiple systems the scanner will hang on conventional systems for about 4-5 seconds when the hold time set at 1 second. Increasing the squelch setting to max has no effect. When I park it on a conventional channel in csq mode the squelch will open at 2 or 3. Not sure why the scan issue is occuring. I know from past experience with these scanners that this same symptom would occur if the squelch was turned down to zero.

On a positive note I have noticed some weak signal stations are coming in a bit better than before the mod. Testing on the 2 meter and 440 ham bands, some distant NWS channels for starters. A weak conventional P25 repeater is also monitorable now.

 

[Boatanchor]

I just did the mod to one of my 996XT scanners. I'm experiencing an adverse side effect as others have mention with the squelch. When I scan multiple systems the scanner will hang on conventional systems for about 4-5 seconds when the hold time set at 1 second. Increasing the squelch setting to max has no effect. When I park it on a conventional channel in csq mode the squelch will open at 2 or 3. Not sure why the scan issue is occuring. I know from past experience with these scanners that this same symptom would occur if the squelch was turned down to zero.

On a positive note I have noticed some weak signal stations are coming in a bit better than before the mod. Testing on the 2 meter and 440 ham bands, some distant NWS channels for starters. A weak conventional P25 repeater is also monitorable now.

Are you running a pre-amp or 'active' splitter?

Reason I ask is that the Uniden scan system does appear to monitor RSSI as well as the squelch condition. If you have a moderately high noise floor, the conventional scan speed can slow down considerably even though the mute is not opening.

You can test this by disconnecting the antenna from the scanner and then note the conventional scan speed increase.

This may well turn out to be an undesirable side effect of the filter change mod and if so, it highlights the importance of users retaining the original filter in case they need to go back to stock.

There may well be hidden menu/software alignment points that can be accessed to counter this issue.
I have seen some alignment settings highlighted somewhere, so will go hunting...

 

[Skypilot007]

Are you running a pre-amp or 'active' splitter?

Reason I ask is that the Uniden scan system does appear to monitor RSSI as well as the squelch condition. If you have a moderately high noise floor, the conventional scan speed can slow down considerably even though the mute is not opening.

You can test this by disconnecting the antenna from the scanner and then note the conventional scan speed increase.

This may well turn out to be an undesirable side effect of the filter change mod and if so, it highlights the importance of users retaining the original filter in case they need to go back to stock.

There may well be hidden menu/software alignment points that can be accessed to counter this issue.
I have seen some alignment settings highlighted somewhere, so will go hunting...

Thanks for the fast reply.

I am using an active antenna multicoupler and as you suggested that seems to be the issue. I removed it and put the stock telescoping antenna on it and the scanner behaves normally. Next I will test the outdoor antenna without the multicouple but I have to do some shuffling of cables. I will test this tomorrow and check back in.

 

[PiccoIntegra]

There may well be hidden menu/software alignment points that can be accessed to counter this issue.
I have seen some alignment settings highlighted somewhere, so will go hunting...

There is only one setting(voltage adjustment) that I'm aware of that can be tuned. It's a hidden setting in one of the test modes. It also involves a four digit pass code to access. I will not post the procedure in these forums however. This is something that does not need to be common knowledge. The issue has more to do with not knowing what exactly this affects, and I don't know if modifying this setting can hurt the radio. I do know it's some sort of signal voltage reference. I've only accessed it once, and backed out of it soon after.

I wish I had ordered a set of these filters though, I didn't think they'd disappear so fast. I was waiting for more feedback before pulling the trigger. :roll:

 

[Boatanchor]

Scan speed and noise floor

Interesting.

I've got three x96XT scanners. Two of which have been modified and one is stock standard.

I live in a relatively RF noisy neighborhood, with the usual candidates such as nearby plasma TV's, computers and even noisy power lines all generating their fair share of crud on the VHF bands.

I also run a discone base antenna, LNA and Minicircuits splitter which runs all my scanners.
The VHF noise floor at my home location varies greatly with the time of day, with the highest noise during the day and the quietest at night.

I've just tested all three scanners on the base antenna at my location and today there is no difference in conventional scan speed between the modified and un-modified units. It is relatively slow on all three!

If I disconnect the antenna, the conventional scan speed increases on all three.

Unfortunately, there may not be much that can be done about this. There is obviously some mechanism within the firmware, that slows the scan speed down if the noise floor exceeds a certain level. I suspect that this was done intentionally to improve the reliability of the squelch operation under noisy conditions. But, I may well be barking up the wrong tree.

More testing required..

 

[Boatanchor]

Test results of noise floor impact on scan & search speed

To be updated..

Wish I had a damned circuit diagram

 

[KevinC]

Interesting.

I've got three x96XT scanners. Two of which have been modified and one is stock standard.

I live in a relatively RF noisy neighborhood, with the usual candidates such as nearby plasma TV's, computers and even noisy power lines all generating their fair share of crud on the VHF bands.

I also run a discone base antenna, LNA and Minicircuits splitter which runs all my scanners.
The VHF noise floor at my home location varies greatly with the time of day, with the highest noise during the day and the quietest at night.

I've just tested all three scanners on the base antenna at my location and today there is no difference in conventional scan speed between the modified and un-modified units. It is relatively slow on all three!

If I disconnect the antenna, the conventional scan speed increases on all three.

Unfortunately, there may not be much that can be done about this. There is obviously some mechanism within the firmware, that slows the scan speed down if the noise floor exceeds a certain level. I suspect that this was done intentionally to improve the reliability of the squelch operation under noisy conditions. But, I may well be barking up the wrong tree.

More testing required..

I found what killed my Unidens was VHF TV stations, once I filtered out channels 8, 11 and 13 (all transmiting from the same general area and about 7 miles from me) my VHF hi-band came alive.

Likewise when I filtered the FM broadcast band my GRE-based radios came alive.

I'm a filteraholic!

 

[kruser]

I found what killed my Unidens was VHF TV stations, once I filtered out channels 8, 11 and 13 (all transmiting from the same general area and about 7 miles from me) my VHF hi-band came alive.

Likewise when I filtered the FM broadcast band my GRE-based radios came alive.

I'm a filteraholic!

I'm in the same boat but must also filter the common VHF paging bands.

Curious as to what type or brand notch filters you used for the TV channels?

I built some stubs just to confirm the problem was from the few remaining VHF TV stations still broadcasting here but they are too wide for my likings so I need to get something with a sharp and narrow skirt like the PAR's I use for paging and FM Broadcast bands. I've never tried PAR's TV filters so looking for advice on what you used.

Most of our area TV broadcasts moved up into the UHF band when the digital switch took place and that helped tons with low band. But, a couple moved back to VHF after they shutdown the old analog transmitters and their temp UHF transmitters.

And like you, FM radio broadcast and paging kills the GRE's while TV broadcast desenses the Unidens. Nothing phases my older Icom's though!
I wish scanners had Icom quality front ends and filtering in them but then most could never afford them.

 

[KevinC]

I'm in the same boat but must also filter the common VHF paging bands.

Curious as to what type or brand notch filters you used for the TV channels?

I built some stubs just to confirm the problem was from the few remaining VHF TV stations still broadcasting here but they are too wide for my likings so I need to get something with a sharp and narrow skirt like the PAR's I use for paging and FM Broadcast bands. I've never tried PAR's TV filters so looking for advice on what you used.

Most of our area TV broadcasts moved up into the UHF band when the digital switch took place and that helped tons with low band. But, a couple moved back to VHF after they shutdown the old analog transmitters and their temp UHF transmitters.

And like you, FM radio broadcast and paging kills the GRE's while TV broadcast desenses the Unidens. Nothing phases my older Icom's though!
I wish scanners had Icom quality front ends and filtering in them but then most could never afford them.

I have all PAR filters, one stock FM broadcast and 4 custom (TV channels, 8, 11, 13 and 19). Dale is awesome in my opinion and will make whatever filter you need, as long as physics doesn't get in the way.

And I too tested with open-stubs to confirm the frequencies I needed to notch.

 

[Skypilot007]

I was able to do a little more testing this evening. It seems I have a relatively low noise floor for VHF/UHF in my area. The closest high power transmitter to my location is a UHF TV transmitter about 10 miles away. It has never caused me any problems. I also have and always have had low noise on HF if that is relevant.

I'm able to use a rooftop mounted 2 meter/440 amateur antenna on the modified scanner without the scan issue. With the stridesburg active multicoupler inline using the same dualbander antenna I have the scan issue. So I suppose there is some noise there that the multicoupler is amplifing that is causing my issues? I will have to think of a way to re organize the antennae to keep the 996 happy for now.

Another positive thing I have noticed is that when monitoring 3 local phase I P25 trunk systems I used to get a lot of digital noise before a transmission would start randomly. I have not heard any of that noise since doing the modification. Decode of P25 seems more solid on weaker signals also. I'll continue to update my observations if it seems relevant.

 

[RRR]

Gang,
like I posted earlier. I can do this mod for folks. I have extensive SMD repair experience for the DoD. If you want to send me your scanner just send me an email at ka3nxn(at)comcast.net. I just ordered eight of these filters and I have 4 of my own scanners to do.

Mr. Bernate (KA3NXN) did the filter mod. on a 996XT for me, and I am VERY impressed with not only the workmanship and the quick, seamless transaction, but also how he took the time to explain exactly what was going on, and the cost and turnaround was very reasonable.

I'm so happy with it, I am sending him another one to do.

Thank you, Mr. Bernate!

 

[kellykeeton]

a status update on the squelch problem, I modded two radios one I took time on the other I did quickly, one radio is working fine. the other radio sounds like crap - after about 4 hours of use the radio was deaf. couldn't pick up anything. and sucked, before going back to the factory filter.

I did just pull the filter G and put a new one in - this time taking time to transfer little to no heat to the component (basically doing a good job like I hadn't before)

the scanner is currently working OK again, no squelch problems. I will run it for 24 hours again and see what happens

anyway just a update for those with problems, I do have spare filters that if you PM'd me I will be willing to ship out for $2 I will get them in order received and will ship them out later I am away on work.

 

[maus92]

I'm curious if this mod would work on a really old Uniden scanner - BCD785D?

 

[wx5uif]

Got mine about an hour ago. Already changed my bcd996xt and bcd996t. So far I can tell a pretty big difference in my local P25 system.

 

[scottyhetzel]

I'm curious if this mod would work on a really old Uniden scanner - BCD785D?

Boatanchor: If the 785/6 are anything like the BCD-780XLT, they may even be easier/better to modify than the newer models.

The BCD-780XLT actually had two 450Khz IF filters installed at the factory!
They had a 50D and a 50F installed. Presumably, these were for FM and AM respectively. I can't confirm this, but it is conceivable that FMN was also piped through the 50F filter, along with AM.
If so, there may not be much point in modifying these radios.

 

[wise871]

I received mine today. Only took a week to arrive. I don't know when I plan to upgrade mine.