Yet another antenna question, this time, involving pre-amps

[Wahoos4Life]

I was browsing around scanner masters website lastnight, and came accross Pre-amplifires for scanners


the one I was looking at in preticulour was : WRP-1300 Pre-Amplifier for Wideband Scanners

WRP-1300 Pre-Amplifier for Wideband Scanners

Has anybody had experience with that?

I was thinking about attaching it to the Diamond RH77CA

and using it on the Radio shack pro 106.

How well would this work for me with increasing my range, and improving clarity(ridding of interfearnce) over the standard stock antenna that comes with the 106.

 

[n5ims]

Antenna pre-amps generally don't work as well as one might expect. Especially ones like these that are designed to be placed near the scanner. While they may indeed provide the advertized gain, 13 db in this case, this gain is added to both the signal and the noise. What you end up with is a weak signal that is made weaker by the loss in the coax that is then amplified along with all available noise.

Think of a microphone in the wind that is amplified so you not only have a louder voice, but also a much louder wind sound. This often will make the voice less readable.

A better location for your pre-amp would be at the antenna site so you end up boosting the signal prior to the coax loss, giving you more overall signal improvement. This pre-amp would need to be a very low noise one (generally more expensive) as well. While I don't know about this specific pre-amp, since the noise figure isn't mentioned, I would tend to believe that it isn't one of the "low noise" type since this would normally be highlighted in the specs.

Often the most cost effective way to increase signal is to use better coax to reduce the loss.

 

[Wahoos4Life]

Antenna pre-amps generally don't work as well as one might expect. Especially ones like these that are designed to be placed near the scanner. While they may indeed provide the advertized gain, 13 db in this case, this gain is added to both the signal and the noise. What you end up with is a weak signal that is made weaker by the loss in the coax that is then amplified along with all available noise.

Think of a microphone in the wind that is amplified so you not only have a louder voice, but also a much louder wind sound. This often will make the voice less readable.

A better location for your pre-amp would be at the antenna site so you end up boosting the signal prior to the coax loss, giving you more overall signal improvement. This pre-amp would need to be a very low noise one (generally more expensive) as well. While I don't know about this specific pre-amp, since the noise figure isn't mentioned, I would tend to believe that it isn't one of the "low noise" type since this would normally be highlighted in the specs.

Often the most cost effective way to increase signal is to use better coax to reduce the loss.

I should clarify,Im not using any cable, 106 is a handheld and I was going to plug the preamp directly into the scanner, and then the antenna directly onto the preamp.

I kinda understand where you are going with this.

IM new to all this, after 7 months of playing with the 106, Im finally getting pretty comfortable with it, Now Im venturing into the antenna world.

I was looking at the preampand the Diamond antenna for the 106 as an alteranative to putting up a 5ft discone.

IM not expecting the same power as a discone on a roof, but was looking for something close to that ballpark , IM getting the Diamond antenna as a replacement for my stock, and was thinking about adding the preamp for some extra power.

...

Sorry if I am rambaling here.

 

[W6KRU]

I should clarify,Im not using any cable, 106 is a handheld and I was going to plug the preamp directly into the scanner, and then the antenna directly onto the preamp.

I kinda understand where you are going with this.

IM new to all this, after 7 months of playing with the 106, Im finally getting pretty comfortable with it, Now Im venturing into the antenna world.

I was looking at the preampand the Diamond antenna for the 106 as an alteranative to putting up a 5ft discone.

IM not expecting the same power as a discone on a roof, but was looking for something close to that ballpark , IM getting the Diamond antenna as a replacement for my stock, and was thinking about adding the preamp for some extra power.

...

Sorry if I am rambaling here.

Don't think preamp, think better antenna. A preamp is no substitute for a proper antenna. Can you at least hang a RS 20-176 in your shack and disguise it as a mobil or something?

 

[Wahoos4Life]

Don't think preamp, think better antenna. A preamp is no substitute for a proper antenna. Can you at least hang a RS 20-176 in your shack and disguise it as a mobil or something?

well the Appearance and other what nots arent that big of a deal, at home. But I was hoping that when I get the Diamond antenna as a replacemnt for my 106 stock, I could also get something for it to add alittle more boost for when Im around the house, and out and about town.IF the Diamond even needs it

I was looking to make my total range from my current destination to 60miles

 

[gewecke]

Getting your antenna outside and as high as you can will be the best way
to get the range you desire. A preamp is no substitute for a good antenna system.
N9ZAS.

 

[kcoleman]

I have the GRE preamp and the PSR-500 radio. Something that is not shown on the Watson unit... is there an adjustable gain? This would be on the opposite side from what is pictured. One thing to keep in mind with the GRE scanners... they are very sensitive on the front end and boosting the signal with a preamp may just make the radio deaf to some degree instead of helping.

I agree with the others, that you will pull in more noise along with the signal. The best success that I've had with my preamp is to keep the adjustment well below the maximum level. With the ability to adjust the amount of amplification, you can better tune the signal to something that isn't too harsh to listen too.

Good Luck & Good Scanning...
Keith

 

[zz0468]

The problem with the preamps marketed toward scanner users is, they usually leave out the single most important specification - noise figure. The bottom line is, unless the noise figure of the preamp is lower than that of the scanner, it's not going to enhance weak signal reception. You may "get more bars" on a signal, but that means absolutely nothing in terms of how well you're actually receiving.
I'd like to see NF listed as a spec for scanners, as well as preamps. Then you could make some half-way informed decisions. And I haven't even addressed overload immunity.

I measured several scanners a few years ago. NF was generally around 6 db. Pretty cruddy. A lot of TV type preamps are around 8 db, so while they make strong signals stronger, they make weak signals disappear into the noise. But they help when you put them in front of an old tv with a 12 db NF.