HP-1: Question about using Powered signal amplifier

I just received a Home Patrol 2 and was wondering if using a pre amp for it will be
beneficial or possibly harmful. I have a M-75 from JIM.
It is and I quote a "Low Noise Wide Band GaAs FET preamp" . I am not new to scanning but new to owning a digital scanner. Help please. I am using a Radio Shack multi freq. crap antenna.

waterdog1955 said:

I just received a Home Patrol 2 and was wondering if using a pre amp for it will be
beneficial or possibly harmful. I have a M-75 from JIM.
It is and I quote a "Low Noise Wide Band GaAs FET preamp" . I am not new to scanning but new to owning a digital scanner. Help please. I am using a Radio Shack multi freq. crap antenna.

Click to expand...

Unless you have an external antenna with a very long run of cheap coax (more than 30 feet or so), it would do more harm then good. And the amp would have to be mounted directly at the antenna.

And in that case it would be cheaper to get some LMR400 low loss coax. If you're using the stock antenna all you will do is overload the front end with an amp.

You will not harm the scanner by using a preamp with it. The scanner's performance might suffer if the preamp overloads the scanner but its performance will return to normal when you remove the preamp. No preamp is going to able to put out enough power to harm a scanner.

Your question about helping your scanner's performance is harder to answer. Without know anything about your individual scanner, about all I could say is that it probably won't help. Unless your scanner is defective it won't need additional RF amplification. All modern-day scanners have about all the sensitivity they can use and adding more won't really do anything to help the scanner. There might be special circumstances where a preamp MIGHT help but they would be few and far between.

Your money would be better spent in improving your antenna system - better antenna, lower loss feedline, etc.

The pre-amp will not harm your scanner and it *may* improve reception. There are a lot of variables at play, so the only way to tell for sure in your situation it to try it out.

I own both the Uniden HP-1 and HP-2 and exclusively use them to monitor activities on the local sites of a large, regional 700/800mhz trunked system. Sometimes I want to monitor activity that is not carried on my local sites, so I need to monitor remote sites which introduces the need to use an outside antenna. I also needed the antenna to be above the roof, since the remote sites are not line of site to ground level and I have tech-shield roofing to compound the issue.

I live in an antenna restricted neighborhood, so I have to use a compromise antenna for this purpose, I chose to place a center fed 1/2 dipole vertically inside a vent pipe. This meant a long coax run, but the remaining space I had drilled through the wall stud would not allow another LMR400 cable. Faced with an extremely difficult drilling situation vs. using smaller coax (which I already had), I decided to source a low noise, narrow bandwidth pre-amp to be mounted up by the antenna.

Using the RF Power Plot function in the Homepatrol Extreme option set to the remote site's control channel, I bench tested the effectiveness of the system. I made a short, Youtube video to demonstrate the effectiveness of this configuration. I turned on the amp about halfway into the video. You can see and hear the night & day difference. Link: https://www.youtube.com/watch?v=ZwdLujWR6L8

Below is a picture of my antenna garden (it’s hardly a “farm&#8221. Not a peep from the HOA in the years it has been there.

waterdog1955 said:

... I am not new to scanning but new to owning a digital scanner. ...

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A digital scanner is just like any other scanner, except for the type of modulation. It's roughly like the difference between AM and FM.

I do have a outside antenna with over 75 feet of Radio Shack wire so I'm guessing that it would not help. Thanks for answering my question.

Thanks to all of you guys for answering my question.

waterdog1955 said:

I do have a outside antenna with over 75 feet of Radio Shack wire so I'm guessing that it would not help. Thanks for answering my question.

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I think you read me wrong... with 75 feet of crap Radio Shack wire, an amp will make a HUGE difference, especially at 800 mHz, as long as it's located at the base of the antenna. If you put it at the scanner end, all you will be doing is amplifying noise.

With that long of a run of cheap coax at 800 mhz you are losing 10 db or 90% of your signal!!! At 450 mhz, you are losing 80%.

You are probably better off with a telescopic whip on the back of the scanner unless you are in a basement or something. Even with LMR-400, you will be losing 50% of your received signal at 800 mHz... this may be acceptable depending on how far out you are trying to listen.

Try putting the antenna closer to the scanner using a minimum amount of coax, just getting it outside even if it's not elevated much should give you a huge improvement over what you have going on now.

waterdog1955 said:

I do have a outside antenna with over 75 feet of Radio Shack wire so I'm guessing that it would not help. Thanks for answering my question.

Click to expand...

You definitely read my post wrong. Watch the video I posted.

I have a roof-mounted discone antenna with very low-loss Belden coax that feeds into an ICOM R-7100 in the attic. But when I got an HP-1, I wanted to use it on the 1st floor of the house. Since I already had a run of cheap RG-58 coax going down thru the wall from the attic to the 1st floor, I put a JIM M-75 preamp between the Belden coax and the cheap coax. This solution works pretty well, the preamp overcomes the loss suffered thru the cheap coax. However, I don't use the preamp at full gain because it causes intermod in the HP-1. I use about 75% gain. I power the preamp with an external 12 volt DC power supply because the JIM M-75 eats up 9-volt batteries like candy.

Again thanks to all of you for you replies. I have ordered a ST 2 and will relocate the Antenna to around a 25 foot run. You guys are great for taking time to help us technology and electronics challenged folks!.