396XT on External Antenna (VHF-AIR)

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SCPD

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Can others respond to their VHF-AIR performance using an external antenna? My 396XT is absolutely terrible! It's shocking that's it's so bad. I am using the latest firmware. I've also tried with AGC on and off.

Test scenario:

Hook up my R/S Discone antenna to Icom A6 transceiver. Punch in BFI ATIS at 127.75 mhz. It comes in loud and clear - full quieting - not an ounce of white noise. (This airport is less than 10 miles from me and I'm located on top of a hill.)

I hook up my 396XT and nothing. If I go to squelch setting 0 then it's barely audible with some sort of white noise covering up the signal. It sounds almost as if I'm getting some kind of overload or interference in the XT.

UPDATE: After tinkering with various antennas and setups, I've discovered that I'm getting extremely bad overload on VHF-AIR (AM mode.) I *must* use the ATT when listening to a channel. When using ATT on this channel, the "white noise" disappears and the signal sounds much better. (The audio quality still doesn't sound great, but it's acceptable.)

When scanning this conventional group (VHF AIR), the scanner seems to be fine; however, it still won't stop on the ATIS channel.

Is this normal for others when using an external antenna?
 

SCPD

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Yeah sorry I didn't mean to double-post that other response. I created it but I thought I had gone back to re-post in a new thread.

Kind of a bummer. It seems to be fine on the stock rubber duck... it just gets bad on the external.

Does the BCT-15 series share this problem too? VHF-AIR seems to be okay in the car...
 

DCMon

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I too posted on the other thread but my XT & T works great on VHF, VHF Air. So I am thinking there is more to this than just the radio. I hear planes 150+ miles away on a rubber ducky (not stock) antenna with the squelch set on 2.
 

SCPD

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Well, the reason I created the seperate thread is because I'm using an external antenna. My rubber duck works fine (if I'm outside for example.) Inside a building, it's okay but I wouldn't say it's very sensitive - but not "deaf" either.

The Icom A6 is way better in terms of sensitivity in all cases.

My guess is that the Uniden is just getting overloaded. I'm sure the Icom A6 likely has filtering elements for just VHF-AIR, so that could help with it's sensitivity and overall reception/performance.
 

gus88

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My guess is that's the way the radios are made. I have a GRE PSR-400 & a Yaesu VR5000, and both go deaf on hi-VHF with an outdoor antenna.
 

KD4UXQ

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Front End Saturation

You are experiencing front end overload. The first RF amplifier in the scanner is being overloaded with strong signals and it is effectively causing the front end RF amplifier to be saturated which essentially shuts it down.

The front end amplifier section is broad band. It receives all signals that the scanner can tune to so it is any frequency in the range or several strong signals combined in the entire range that is saturating the front end RF amp. This is why the attenuator works at solving the problem. Actual selection or tuning of any specific frequency is done in the IF stages of the scanner.
 

JASII

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My guess is that's the way the radios are made. I have a GRE PSR-400 & a Yaesu VR5000, and both go deaf on hi-VHF with an outdoor antenna.
Well, the reason I created the separate thread is because I'm using an external antenna. My rubber duck works fine (if I'm outside for example.) Inside a building, it's okay but I wouldn't say it's very sensitive - but not "deaf" either.

The Icom A6 is way better in terms of sensitivity in all cases.

My guess is that the Uniden is just getting overloaded. I'm sure the Icom A6 likely has filtering elements for just VHF-AIR, so that could help with it's sensitivity and overall reception/performance.
You are both correct. When you look at scanners, they cover a very wide range of frequencies, and they aren't as sensitive as a transceiver that is made for a specific band. Over the years that I have enjoyed this hobby, I have used:

-scanners

-amateur radios

-commercial land mobile

-communications receivers

All have some pros and cons. Generally I listen to narrow band FM, but the same thing applies. The scanners are reasonable priced, generally scan fairly fast, and often have a high channel capacity. They sometimes aren't as sensitive as we would like, however.

The amateur radios I have used, currently Yaesu FT-8800s, are generally slower scan speed, often have a pretty good channel capacity, and can have good sensitivity. Usually they don't have quite the wide range of scanners though. My FT-8800s cover VHF high band, UHF, and 800, but it simply doesn't have VHF low band. I suppose an FT-8900 adds VHF low band, but then you lost the ability to configure banks of frequencies.

I have a couple of Bendix King portables, one VHF and one UHF. They are certainly no Motorolas, but they work pretty well. They simply won't scan more than 14 channels at a time, however.

The absolutely most sensitive communications receive that I have ever owned was the AOR AR-5000. It was very sensitive and very selective all over the bands that it covers. I had the optional CTCSS decoder, but it doesn't do digital PL, or APCO P-25, or trunking.

That is one of the interesting things about electronics, to me. We want an all-in-one device. We want the iPod of radios, so to speak. I don't think we are there yet, and may never be.

I see the same concerns with the GPS, MP3, and cell phone markets. Again, the iPhone, iPod Touch, Blackberries are very popular. So are Garmin, Tom Tom, Magellan, and other stand alone GPS devices. I use GPS every day for work, I also use cell phone and radio every day for work. I actually prefer them to be separate. I don't want to stop navigating because a phone call comes in. Nor do I want to have to ignore a call because I am navigating.

In my personal life for entertainment and navigating, I well may end up with two devices. In the spirit of a true typical tight-wad ham radio operator, I don't like paying recurring monthly fees. Thus a pre-pay cell phone in my personal life. I also don't like buying MP3s, thus slacker radio. I also don't like paying for a data plan, thus a stand alone GPS phone. I simply can't get all of that in one device. The best I can do is two devices. A used Blackberry 8350i may be in my future. Blackberry is currently the only cell phone that will cache Slacker Radio (others stream Slacker Radio). I have a Pharos GPS Phone 600 that is bought used. It is unlocked GSM and will work with T-Mobile pre-pay. I have installed Garmin Mobile XT on a micro SD card on this and it is an excellent GPS navigator. I will eventually get a used Garmin Nuvifone.

Anyway, I apologize for the length of this post, but the point is you very well may want to continue using more than one device for monitoring. As we speak, I have a Motorola 800 mHZ XTS 5000 portable near me. It is no Uniden Bearcat BCD996XT. I also have a BCD996XT near me and it is no XTS 5000. Both are great, but neither replaces the other.
 

pdfdems286

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I have a couple of Bendix King portables, one VHF and one UHF. They are certainly no Motorolas, but they work pretty well. They simply won't scan more than 14 channels at a time, however.

while i agree with what you said for the most part, and you are entitled to your opinion.i believe that the b-k line of portables do about the same as a motorola & cost a little less. also, there is a software modification that allow's your radio to "group scan". you have to have it enabled, and press a series of command's via the keypad. now keep in mind,it's a little bit of a pain because you have to lockout/unlock what you do & don't want. i wish i had never sold my v/u kings.

i currently have a yaesu vx-6 that does real well as a scanner.
 
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jdm911

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Not to reopen such an old thread but shocking is the correct word. I love my bcd996xt, it is a great radio for what I use it for...but, after spending all day on doing things right and installing a RS Sputnik on the eve of my roof I was very disappointed with the radio's performance. I have an ICOM 2000H that is now hooked up to the radio and I cannot believe the distances that I am hearing. The uniden was receiving 800 pretty very well on the antenna but VHF from a county over was nill. I was sure that I did something wrong, glad that I had the 2000H to hear how well things were actually working.
 

SkipSanders

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The very first thing you must do on putting any outside antenna on any scanner, most especially if you in any kind of urban area, is put an FM Broadcast Band trap on that antenna!

FM stations are regularly a major cause of front end overload/desense on scanners, which in general aren't designed for outside antennas, as the manufacturers expect almost all users will only use a back-of-set antenna.
 

UPMan

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In the interim, see if turning on attenuation improves reception.
 

jdm911

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Would it be safe to say that it is the FM broadcast band (as previously mentioned by Skip) that is causing the problem rather than paging frequencies? I only suggest this because, even though the ICOM would be susceptible to some pager inter. (as the radio covers this freq. range), I have not heard any such problems. Is it then the safe assumption that, because the ICOM does not receive the FM Band, that it is not being overloaded by that range of frequencies and that because of this, the FM Band is what is causing the problem on the 996xt? I will be doing some testing when I get home, I am just thinking out loud about determining which filter I really do need.
 

pyteen

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Well known that Uniden scanners have poor front end. Best way to solve that issue use band pass filter. In my area so many strong signals that i use narrow (3-5 MHz) helical or cavity filters on VHF. If you use ARC software try bandscop to see noise level.
 

kayi4cle

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For what it's worth, I have a Uniden BCD996T and Radio Shack Pro-197 side by side in the house, and each hooked to a separate magmount with identical antennas. I get better VHF reception on the 996T.
 

UPMan

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Well known that Uniden scanners have poor front end.
Should probably edit that to say:
Well known that all scanners have a wide front end.
Unlike transceivers which operate in a very narrow band of frequencies, Scanners must have a pretty wide open front end in order to be able to operate on 29-1300 MHz. Industry-wise, Uniden is more known for having a tighter front-end (which can also come across as "less sensitivity") so that it generally operates better than the competition in high RF environments but needs more antenna if you are out in the boonies. There is a limit to how much signal can be coming in before desense occurs (on any rig). Scanners are more prone to it due to their wide frequency coverage.
 
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