BC125AT: In service search mode for Military Aircraft FM default issue on BC125AT

[Rifleman336]

I'm the proud owner of 3 BC125ATs, and one little annoying fly in the ointment is that in service search mode 7 (Military Aircraft), the scanners firmware has the VHF 130/140s as WFM mode vs AM.

As a active Military aircraft monitor of almost 30 years, most of the military air to air activity is in AM mode. Is their a way the end user can correct this? Or in future like models would it be suggested that this be changed or a firmware update offered.

 

[JoeBearcat]

The Service Search was recently updated. I am hoping those changes port to the older models.

 

[GROL]

The Service Search was recently updated. I am hoping those changes port to the older models.

Could a firmware update of the BC125AT add back the missing 380-400 MHz segment that Uniden mistakenly considered was only for P25 trunked systems? I can assure you that US military aircraft still operate AM mode at 25 KHz channel spacing between 380 and 400 MHz. The BC125AT would become more popular for Mil Air monitoring. I never would buy one for that reason. This has been discussed several times. There are many recently confirmed AM mode transmissions in 380-400 MHz. 380-400 is not dedicated to only trunked systems and probably never will be. 225-400 MHz is not dedicated to any particular mode or service. At least an updated version for US should be considered for sale. The UBC125XLT and UBC126AT have 380-400 MHz and are essentially the same radio except service searches and 25-88 MHz and 225-550 MHz is a different band limit from the BC125AT.
Observe one example. Harrisburg PA Air National Guard Ops is 395.1 MHz. AirNav: KMDT - Harrisburg International Airport

AirNav: KMDT - Harrisburg International Airport

Complete aeronautical information about Harrisburg International Airport (Harrisburg, PA, USA), including location, runways, taxiways, navaids, radio frequencies, FBO information, fuel prices, sunrise and sunset times, aerial photo, airport diagram.

airnav.com

 

[Scan125]

The Service Search was recently updated. I am hoping those changes port to the older models.

Joe, you will also see request for frequency range expansion if possible. This linked table shows you a quick summary of the BC125, UBC125, UBC126 scanners.

Scan125 Control Program User Manual

Internal hardware / filter differences are unknown but I'm sure Uniden must know what they are, if any?

 

[GROL]

Joe, you will also see request for frequency range expansion if possible. This linked table shows you a quick summary of the BC125, UBC125, UBC126 scanners.

Scan125 Control Program User Manual

Internal hardware / filter differences are unknown but I'm sure Uniden must know what they are, if any?

I would believe the RF hardware is exactly the same. If it cannot be changed with a firmware update, then it would probably just be a difference in the CPUs. But it was still a mistake to cripple the BC125AT on an assumption.

 

[Scan125]

I would believe the RF hardware is exactly the same. If it cannot be changed with a firmware update, then it would probably just be a difference in the CPUs. But it was still a mistake to cripple the BC125AT on an assumption.

I have the circuit diagrams for the UBC125XLT but not the BC125AT.

 

[GROL]

I have the circuit diagrams for the UBC125XLT but not the BC125AT.

Would be interesting to see. Darn shame the taxes in the UK and Australia make them cost so much, and then the shipping makes them about $275 total. If not I would by a UBC125XLT or BC126AT.

 

[Scan125]

Would be interesting to see. Darn shame the taxes in the UK and Australia make them cost so much, and then the shipping makes them about $275 total. If not I would by a UBC125XLT or BC126AT.

Index of /scan125/schematics

 

[GROL]

Index of /scan125/schematics

Thanks! Darn shame the BC125AT is crippled. That schematic shows there are switched RF filters on the front end which makes for a good wideband receiver with limited out of band interferences. Usually would not expect to see that in a low cost scanner. I doubt the filters are different between the BC125AT and the others. Wouldnt need to be just to cut out 380-400 MHz. Also see it is double superhet and see the two different first IFs for the IFX. Quite a bit in the design.

 

[Scan125]

Thanks! Darn shame the BC125AT is crippled. That schematic shows there are switched RF filters on the front end which makes for a good wideband receiver with limited out of band interferences. Usually would not expect to see that in a low cost scanner. I doubt the filters are different between the BC125AT and the others. Wouldnt need to be just to cut out 380-400 MHz. Also see it is double superhet and see the two different first IFs for the IFX. Quite a bit in the design.

Well thanks for your "expert RF View" ? . It would make sense for the BC125AT, which was the base for the UBC125XLT versions to be very similar.

What I find frustrating as a UBC125XLT user is that there are no firmware updates (*ever*) available after purchase. Any differences in firmware are are factory ship based. I know for a fact that the UBC125XLT gets the air band 8.33 freqs wrong in some cases and my Scan125 program can correct for this. The UBC75XLT seems to these 8.33 freqs correct.

I've no idea what the BC125AT does with the 8.33 freqs as I don't own this model but Scan125 will correct if asked/directed to.

 

[GROL]

Well thanks for your "expert RF View" ? . It would make sense for the BC125AT, which was the base for the UBC125XLT versions to be very similar.

What I find frustrating as a UBC125XLT user is that there are no firmware updates (*ever*) available after purchase. Any differences in firmware are are factory ship based. I know for a fact that the UBC125XLT gets the air band 8.33 freqs wrong in some cases and my Scan125 program can correct for this. The UBC75XLT seems to these 8.33 freqs correct.

I've no idea what the BC125AT does with the 8.33 freqs as I don't own this model but Scan125 will correct if asked/directed to.

Not a review. An observation of the RF design which is very good for an inexpensive scanner. Understanding that schematic is within my education and experience level. It is a classic design without any oddities.

 

[captainmax1]

The Service Search was recently updated. I am hoping those changes port to the older models.

Let us know if you hear rumor of the older AT125's getting the update or if it's limited by hardware. Not any news on update site yet. Also, I think you're stating that the newer 125's have the update. The AT125 is my go-to scanner for everything analog.

 

[captainmax1]

I asked Scanner Master about the missing 380-400 range added on the new BC125AT's and this was their response:

From the box cover it says it will cover 25-54, 108-174, 225-380, 400-512. But it also says it covers Civilian & Military Aircraft Frequency Bands.
I assume that the range you asked about is not included.

 

[GROL]

I asked Scanner Master about the missing 380-400 range added on the new BC125AT's and this was their response:

From the box cover it says it will cover 25-54, 108-174, 225-380, 400-512. But it also says it covers Civilian & Military Aircraft Frequency Bands.
I assume that the range you asked about is not included.

That's the point. An important segment of Military Air coverage is missing. 380-400 MHz. I haven't visited Shaw AFB in a few years but their CP frequency is still 381.3 MHz. AirNav: KSSC - Shaw Air Force Base.

PA Air National Guard CP in Harrisburg is 395.1 AirNav: KMDT - Harrisburg International Airport

 

[JoeBearcat]

Also, I think you're stating that the newer 125's have the update. The AT125 is my go-to scanner for everything analog.

I did not say new 125s.

But I hope the updates port back to the 125 that will cover existing and new models of the 125 (and others).

 

[JoeBearcat]

That's the point. An important segment of Military Air coverage is missing. 380-400 MHz. I haven't visited Shaw AFB in a few years but their CP frequency is still 381.3 MHz. AirNav: KSSC - Shaw Air Force Base.

PA Air National Guard CP in Harrisburg is 395.1 AirNav: KMDT - Harrisburg International Airport

I did not make that call, but the 380-400 MHz segment was supposed to be reassigned to trunked systems.

 

[GROL]

I did not make that call, but the 380-400 MHz segment was supposed to be reassigned to trunked systems.

I don't believe it was ever supposed to be "reassigned". They assigned frequencies in that range to trunked systems. When they did assign frequencies there to trunked radio, there was an assumption it was reassigned. Since it was not reassigned, it should be included on analog scanners.

 

[JoeBearcat]

How would we be able to search that without running across trunked systems that would hang up the search (largely unheard due to the AM mode). Is there some scheme out there that is able to distinguish between the frequencies used? (such as 25 kHz used for air and 12.5 kHz used for trunked)

 

[GROL]

How would we be able to search that without running across trunked systems that would hang up the search (largely unheard due to the AM mode). Is there some scheme out there that is able to distinguish between the frequencies used? (such as 25 kHz used for air and 12.5 kHz used for trunked)

Searching may be an issue if you are near a trunked system between 380 and 400, but scanning programmed frequencies would not of course be an issue. I am not often near a trunked system even when searching between 380 -400 MHz. You don't have to be near a military base to monitor military aircraft. 12.5 khz trunked spacing is going to include the 25 khz spaced frequencies. All AM air-air and ground -air aviation frequencies are 25 khz channel spacing. You could avoid a lot setting modulation mode to AM and channel spacing to 25 khz, and use the frequency lockout when you come upon a digital frequency. Another annoying thing is that some scanners (cheaper models) are setup for only 12.5 khz channel spacing between 380 and 400 that cannot be changed so it slows down searching for milair. Fortunately the BCD325P2, BCD396XT, BCT15X and BCD996P2 I own can be changed to default to 25 khz spacing between 380 and 400 MHz. The two Radio Shack Pro -164 I own are one of the annoying scanners that can only do 12.5 khz spacing between 380 and 400.

 

[Scan125]

All AM air-air and ground -air aviation frequencies are 25 khz channel spacing. You could avoid a lot setting modulation mode to AM and channel spacing to 25 khz, and use the frequency lockout when you come upon a digital frequency.

In the US and other places but in the EU and other places 25kHz and 8.33kHz are used. Certainly 8.33 and 12.5 don't clash except on 25kHz.