antenna options for Uniden UBCD396T. Will UHF CB arial work?

**cr500** · 10-30-2007, 04:12 AM

If I get a Uniden UBCD digital hand held scanner, will I be able to connect it to the UHF CB antenna cable in my work car? Will the CB UHF antenna which work around 470-480 Hz work over a wide range with my digital scanner to get more range than the standard whip arial? Can I use the same cable, but screw in a different antenna?

**o2bad455** · 10-30-2007, 07:50 AM

Originally Posted by cr500

If I get a Uniden UBCD digital hand held scanner, will I be able to connect it to the UHF CB antenna cable in my work car? Will the CB UHF antenna which work around 470-480 Hz work over a wide range with my digital scanner to get more range than the standard whip arial? Can I use the same cable, but screw in a different antenna?

Are you in the States or elsewhere? In the States, CB is a very narrow range at 27 MHz. A UHF antenna is designed to work in the 450 MHz range. I think I've heard of a UHF CB band in Australia. At any rate, a single band wire whip antenna is only going to work well at it's tuned band (bascially determined by whip length plus ballast). Although it is difficult to tell by looking where any given antenna will operate, it is safe to say that shorter antennas operate at higher frequencies than longer ones, in general. As long as nothing is transmitting on the same antenna, your best bet may be trial and error to determine if an antenna works well enough for you over the frequency range in your area.

As far as mounting a more suitable antenna to the existing base, that would probably work fine if you have standard 50-ohm coax between the base and the scanner. The main issue is the different connector types at the antenna and at the scanner. While some are much better than others, connector adapters always introduce some signal degradation. Thus, even if you could find a 3/8-24 to SMO adapter, for example, to mount a scanner antenna to a CB base with a different thread, remember that the antenna will not work quite as well as if it had a matching base to start with.

All that said, I enjoy plugging my BCD directly into a stock AM/FM shorty antenna on the roof of my car. It works well enough for my purposes from about 100 Mhz to 800 Mhz. An AM/FM/Cel antenna might extend the upper range a bit, but would not extend the lower range. A US (27 MHz) CB antenna would probably give good low frequency coverage, but I doubt very much if it would pull any useful signal in the 800-1000 Mhz range.

WARNING/Caveat Emptor: If you do use your CB antenna for scanning, NEVER connect a CB transmitter and the scanner receiver at the same time, or you'll destroy your scanner by transmitting directly into it.

**cr500** · 10-31-2007, 04:10 AM

Thanks for this info. CB in Australia is about 477hz. Since I will mainly be using the scanner in my car, I was hoping to connect it to the arial cable which normaly plugs into my CB. I wouldnt run them both at once though. I was hoping to tune into 70-78hz and @468Hz analog and digital. Will a CB arial tuned for 468-477 hz work well with a scanner? Will it work with digital and analog?
What sort of range will it get with a good 3 or 6db gain UHF arial connected by good coax cable?

**o2bad455** · 10-31-2007, 09:52 PM

This is just a guess, but a simple whip antenna tuned for 477MHz would probably work fine for receive-only on 468MHz. I doubt whether it would work well at 70-78MHz, particularly since 477 is not an exact multiple of 74, but it wouldn't hurt to try.

**cr500** · 11-01-2007, 04:30 AM

So what range do you think I will be able to hear clearly with a 12" long whip antenna on my motorcycle, or with a large full size antenna on my work car.

**cr500** · 11-01-2007, 04:31 AM

So what range do you think I will be able to hear clearly (on 468Hz digital)with a 12" long whip antenna on my motorcycle, or with a large full size antenna on my work car.

**o2bad455** · 11-04-2007, 04:35 PM

It's one of those things that could be figured out if one had enough details about the particular antennas (particularly whether loaded, etc.), but it's just going to be easier plus more accurate to try it and see (experiment).

**o2bad455** · 11-10-2007, 05:01 PM

I'm answering your IM here so others might benefit and/or critique my answers. I'm not posting your actual questions since they were only received by IM.

My guess is that 468 MHz is close enough to such an antenna's design frequency of 477 MHz that you should get good reception on 468 MHz. Digital or analog mode doesn't matter to the antenna.

A big antenna (e.g., 1/4 wavelength) should have excellent reception at its design frequency. While the antenna may be designed for high-power transmit as well as receive, that fact would not hurt it if used only for receive.

I think 78 MHz is just too far from 477 MHz. The wavelength at 477 MHz is about 0.63 meters, but the wavelength at 78 is about 3.84 meters -- that's a huge difference. You could try it, but I suspect you might get poor reception.

**DeadReb245** · 11-10-2007, 10:20 PM

Originally Posted by o2bad455

I'm answering your IM here so others might benefit and/or critique my answers. I'm not posting your actual questions since they were only received by IM.

My guess is that 468 MHz is close enough to such an antenna's design frequency of 477 MHz that you should get good reception on 468 MHz. Digital or analog mode doesn't matter to the antenna.

A big antenna (e.g., 1/4 wavelength) should have excellent reception at its design frequency. While the antenna may be designed for high-power transmit as well as receive, that fact would not hurt it if used only for receive.

I think 78 MHz is just too far from 477 MHz. The wavelength at 477 MHz is about 0.63 meters, but the wavelength at 78 is about 3.84 meters -- that's a huge difference. You could try it, but I suspect you might get poor reception.

I'm with you on this one...78 is too far for a 477 antenna to get decent range. As always, it's worth a shot, but I don't have much faith in it. Let us know.