Help with my PRO-405 (antenna upgrade)

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ceo32312

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I am looking to install an ouside antenna and would like to know what i need to run from my pro-405 (wire?) and what type of outside antenna i should purchase.

I plan on installing my antenna to a spot on my roof.

Thanks
 

ka3jjz

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I'd be a bit careful with this; GRE made radios are very prone to overloading. You're in Wisconsin, right?

Be more specific about what you are listening to - most likely a discone will do the job but let's hear back first...best regards..Mike
 

ceo32312

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Pro-405

Yes, im in Wis (Door County) I just listen to local fire/ems, i kind of have a hard time picking up coverage in the northern part of the county. I thought that an antenna would help.

Any help would be great!
 

ka3jjz

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Yes quite probably. My first thoughts with the antenna would be something with reinforced hardware, due to the storms you likely get being near the Great Lakes. A ST2 Scantenna would not stand up to much of that, and cheap discones are likely to fall apart. These 2 are a start - look at the Omni X from DPD;

DPD Productions - Scanner, Aviation, NOAA, Mobile Radio Antennas for Commercial & Hobbyist Applications

Scanner Antennas | PAR Electronics | Filters for the commercial 2 way market, MATV, FM broadcast, laboratory, marine industry, amateur radio, scanner and short wave listening enthusiasts

If you're further away from the transmitters then a beam is called for - Grove Enterprises sells 'em, as does DPD. But let's start with the simpler solution first.

The next thing to consider would be coax - likely as not a RG6 variety would be right up your alley. You would, of course, need the proper connectors to go to the antenna and scanner - I'm not sure, frankly, who you could ask in your neck of the woods about this - I would check in our Wisconsin forum (note that anything blue is a link).

Next would be waterproofing. The coax going to the antenna is going to take a pounding - wrapping it in a double layer of electrical tape that is then sealed with a silicone sealant at the jack where the antenna and coax mate is going to be vital. Failure to do this will lead to eventual water leakage into the coax, causing signal loss.

Another thing to keep in mind, as mentioned earlier, is the fact that GRE radios are prone to overloading particularly in the VHF hi band, where your transmissions are located. If you find after you get everything up and running that your reception is actually worse than when you started, or you are hearing pagers and other junk, a filter is going to be needed. PAR electronics sells them - and while they tend to be a bit pricey, you get what you pay for.

This should start you thinking...best regards...Mike
 

jackj

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An antenna mounted outside and higher than the scanner's location would help it to pick up weak signals. KA3JJZ says that they overload easily but I can't address that problem as I don't own a GRE/Radio Shack scanner of recent vintage. But there are some general information that holds true regardless of the brand scanner you own.

Wide band antennas are a compromise. They cover a much wider frequency range than dipoles but don't have any gain. There are several different designs for wide band antennas but they all work about the same. They make sense if you are trying to receive 2 or more bands and will work better than attempting to match 2 or more antennas to a single coax.

Regardless of how far the antenna is from the scanner, low loss coax will work better than high loss. It also costs more. RG-58 is good for runs up to about 10 feet long. RG-8x is just a little better while RG-8 is better still. The two main characteristics of coax that you need to worry about are loss and impedance. Loss is measured in decibel or db and less is better. Impedance is measured in ohms, your scanner and antenna will be rated at 50 ohms. Your feedline should match that. You can check the Wiki here or Google coax to get the ratings of different cables.

You probably already knew all that.
 

hertzian

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One problem with the 405 and a good antenna is that the 405 is a dual-conversion unit that uses 10.7 mhz as the i.f. frequency - which makes it possible to hear stations that are not on the displayed frequency, but are actually 21.4 mhz away.

Depending on how swamped your location is with RF, a better antenna might make this situation worse. I'd put up an inexpensive outdoor antenna first just to make sure your 405 can handle it.
 
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