BC780XLT better Low VHF Band sensitivity than BCT15X?

[MattSF]

After adding Cali Hwy Patrol into my new BCT15X I noticed I wasn't hearing anything. The CHP operates in the low 40 MHz range, FM modulation with CTCSS (see Department of the Highway Patrol (CHP) Scanner Frequencies and Radio Frequency Reference). Getting the CHP on my 780XLT has always been a bit low in terms of S/N quality from my house but definitely good enough that the speech was understandable. It doesn't seem to be a selectivity issue per se, since I get "clean" static with the squelch down on either radio.

I thought I had mis-programmed the BCT15X at first (see my previous thread ) but it just seems like its sensitivity in this band is not as good as my 780XLT. I have them sitting about a foot apart on the same table, set to a custom search and then held on 42.4400 MHz (with FM modulation set); the 780XLT can clearly pull in the transmission and speech quality is fair. Meanwhile, the 15X is just mired down in static, speech barely intelligible.

I tried switching their antennas so that now the BCT15X is using the stock supplied antenna and now it's doing slightly better than the common Radio Shack sourced center-loaded telescoping antenna, but still not able to pick out a clear signal on the same frequency. It will at least break squelch with the value set at "01" so that's a good sign, I guess.

Please note this isn't a complaint, just an observation. Fwiw, I plan on dusting off the Diamond D130J antenna I bought years ago but never installed on the roof (yeah I know!) so I hope that will improve things. Otherwise, I guess this is why people keep their older radios around eh? I have heard that the 780XLT is known for its receive quality for the aircraft bands, this might be another example of where it shines.

I'd like to hear others' stories of two radios, one shack...where one radio definitely is the better of the two at receiving a particular band.

 

[gewecke]

After adding Cali Hwy Patrol into my new BCT15X I noticed I wasn't hearing anything. The CHP operates in the low 40 MHz range, FM modulation with CTCSS (see Department of the Highway Patrol (CHP) Scanner Frequencies and Radio Frequency Reference). Getting the CHP on my 780XLT has always been a bit low in terms of S/N quality from my house but definitely good enough that the speech was understandable. It doesn't seem to be a selectivity issue per se, since I get "clean" static with the squelch down on either radio.

I thought I had mis-programmed the BCT15X at first (see my previous thread ) but it just seems like its sensitivity in this band is not as good as my 780XLT. I have them sitting about a foot apart on the same table, set to a custom search and then held on 42.4400 MHz (with FM modulation set); the 780XLT can clearly pull in the transmission and speech quality is fair. Meanwhile, the 15X is just mired down in static, speech barely intelligible.

I tried switching their antennas so that now the BCT15X is using the stock supplied antenna and now it's doing slightly better than the common Radio Shack sourced center-loaded telescoping antenna, but still not able to pick out a clear signal on the same frequency. It will at least break squelch with the value set at "01" so that's a good sign, I guess.

Please note this isn't a complaint, just an observation. Fwiw, I plan on dusting off the Diamond D130J antenna I bought years ago but never installed on the roof (yeah I know!) so I hope that will improve things. Otherwise, I guess this is why people keep their older radios around eh? I have heard that the 780XLT is known for its receive quality for the aircraft bands, this might be another example of where it shines.

I'd like to hear others' stories of two radios, one shack...where one radio definitely is the better of the two at receiving a particular band.

I have never had or played with the BCT15X but I have had my 780 for the past 9 years or so, and there is a neat trick you may already be aware of.
Set all of your FM memories to NFM. Reason being is that it makes a marked improvement in S/N ratio as well as sensitivity. You are right about the 780 being a excellent performer where aircraft is concerned. If mine died tomorrow, I'd either repair it or have a small funeral and jump right online and buy another.

73,
n9zas

 

[Boatanchor]

The discone will certainly help, however I know for a fact that the D130J works about as efficiently as a 'house brick' at 40Mhz.. (not very well at all in other words). It should still outperform your stock scanner antenna on your desk though simply because of the extra height and additional isolation from all the RF pollution inside your house.

I have one and I know that the D130J only works as a discone down to about 100Mhz. There is a 50Mhz resonator but that is very narrow in bandwidth and only marginally works on 52Mhz.

The main issue aside from the poor efficiency of most scanner antennas at 40Mhz, is that the band is very susceptible to RF Interference. Just about everything in the house and nearby houses generates noise on this band. Nearby computers and LCD monitors, TV's and anything with a switch mode power supply or computer in it will probably generate hash and noise at 40Mhz. Moving any antenna away from this noise will improve the S/n ratio considerably.

If you really want an efficient base antenna at 40Mhz, you're probably better off making a simple 1/4 wave ground plane antenna or even simpler, a half wave wire dipole, it would only be 12ft long and could be anchored diagonally from an elevated point on your house like a chimney (remember though the dipole needs to be as close to vertical as possible). Better still, a vertically polarized delta loop as this would provide bi-directional gain and possibly additional noise rejection off the sides of the antenna. Got any convenient trees in your yard?

It's not hard or expensive to experiment with simple, but effective wire antennas at 40Mhz

 

[Boatanchor]

You might even find that the stock AC adapter supplied with your scanner/s generates noise on 40Mhz lol.
I wouldn't be surprised if the adapter is a cheap switch mode supply.

 

[MattSF]

ahh thanks for the info, guys. Yeah I figured that with all kinds of junk in the 40 Mhz range flying around, it's a bit of a challenge (a scan I did at home recently picked up an open baby monitor nearby). I figure you're right about the EMI/RFI that's going on. I was just amazed at the 780XLTs particular ability to do a much better S/N delivery in this particular instance.

Boatanchor: heh I think you're right. My roof only has 1 antenna now (HD TV) ... and we all know a few more wouldn't hurt

gewecke: yeah I read something to that effect about the audio rolloff being different in those modes on the 780XLT, and how you can also use that to your advantage to make signals more intelligible. nice little radio.

 

[GB1952]

YES I HAVE TWO 780s JUST SITTING HERE NOW EVERYTHING IS DIGITAL DONT USE THEM MUCH AT ALL BUT THEY DO PULL IN WHAT LEFT OF LOW BAND (PRISONS) MILITARY ECT.

 

[MattSF]

heh kinda sad a 'vintage' radio dates from the early 2000s

it really wasn't its being analog that made me upgrade, it was the rebanding of the local police/fire/public safety. But yeah like you guys, I'm hanging onto the 780!

 

[Skypilot007]

Yep..I like my 780's, I have two of them and they ain't going anywhere. I too noticed the lack of performance on low band, air band, UHF air band as compared to my 996XT's. The 780's are superior receivers in these areas of the bands. It is funny how Uniden will add all these new fancy features to the newer scanners but come up short on what really makes a scanner good!

 

[737mech]

Better airband 15x

Yep..I like my 780's, I have two of them and they ain't going anywhere. I too noticed the lack of performance on low band, air band, UHF air band as compared to my 996XT's. The 780's are superior receivers in these areas of the bands. It is funny how Uniden will add all these new fancy features to the newer scanners but come up short on what really makes a scanner good!

I still think the 15x and 15 are great on UHF/VHF airband, only problem is I have to use an FM trap inline with the antenna.

 

[MattSF]

It is funny how Uniden will add all these new fancy features to the newer scanners but come up short on what really makes a scanner good!

well it can't be easy trying to make a receiver that has a ton of features, and is also a superior performer across the spectrum... all in a consumer-grade package. I give them a bit of a pass on this one, although yes I was a bit disappointed in this particular case.

Meanwhile I really needed a new receiver due to rebanding in my area, and in the 800 MHz range, the BCT15X sounds nice and clear. Now if I can just get my head around how to properly control the d*mn thing. :-D