800 Mhz Preamp ( In house signal amp )

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andrewccm

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The replacement came in today and it seems to be working. I haven't tested the distance, but I am getting the benefit of my Yagi "wirelessly" now. I am using a DuraCom 13.6v power supply right now. Need to pick up a 24v probably...
 

HOLEBILLY

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what kind of connectors do you need for these to hook up your coax and rubber duck to?
 

andrewccm

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SMA to BNC adapters.

For me, I am using LMR400 from my Yagi using N-Type connectors. I then convert the N-type to BNC for a short run of RG6 to the preamp that has a BNC to SMA adapter. The preamp has female SMA connectors on both sides so you'll need whatever adapter to your type of cabling to a SMA-Male. I have my stock 396T SMA antenna screwed in directly to the output of the preamp.

Hope this helps.
 

andrewccm

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Funny... My first was DOA, and I sent it back. So they sent me a replacement... but accidentally sent me 2 separate replacements. So I have a spare. They told me not to worry about sending it back.

Odd thing...I am having a hard time determining if they are working correctly. I definitely get better 800 when my scanner is directly connected to my Yagi 800 than when the Yagi is run through this amp. I am beginning to think I need to get a 24v to really make a determination. I am a bit confused though.
 

mancow

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I ran mine right off of a 12 v wall wart. It has a 15 v regulator inside so I don't think 24 will help any.

The only thing I can think of is that it is overloading your receiver. Is the system you are monitoring fairly strong in your area to begin with? Do you have much of a congestion of 800 stuff in your area?

I am 30 miles from any hi power 800 transmitters other than nextel/cellular stuff. Perhaps for me it was a combination of a relatively low noise floor and moderately low level target signals that helped my situation.
 

andrewccm

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There are a lot of 800 systems around here. However, the ones I am monitoring with my Yagi are 30-40mils away. When I plug straight into my Yagi, I may get 1 or 2 bars... When using the amp, I get "Finding CTRL Channel" ie, zero bars. I even moved out of my room across the house to insure I wasn't overloading by being too close.

I am confused. I know I am getting power to the unit and I have tried both SMA antenna for the output and a BNC to sma adapter for the output antenna. Perhaps I should switch back to my 12v Duracomm... I was pretty sure it was working when I was using it to power. This 13.6v wallwart is putting out power. I do know that...but it's an old PS. I have tried both amps too...

Scratching head. Thanks for your help. I appreciate it.
 

chris480

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That website doesnt show the box for sell, how much was it? And what is it called so I can try and find one to buy?
Thanks
 

N1SQB

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Just a thought here guys but could the limited range be due to all those adapters being used in line? Is there a way to limit the amount used? Just a thought. With every adapter you get more and more loss. For example, you can mount an SMA duckie antenna directly to the output and just put the darn thing verticaly to save having to use right angle adapters. Second, just use 1 adapter to go from whatever is at the end of your coax (from the antenna) to an SMA male since the connectors are SMA female. I bet you would get more than 20 ft.

Manny
 
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mancow

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Personally, I think the whole adapter loss issue is over hyped. If it's a decent connection the loss should be negligible.
 

chris480

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What is the box called, and where can I get one? I want to try it here in Phoenix and see if I can get the choppy and digital cut in and out fixed. I want to put an ant in my attic and then connect to this with my hand held so I can be all over my house and not hooked to the ant in the attic.
Thanks
 

N1SQB

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There IS a difference,like it or not.

Personally, I think the whole adapter loss issue is over hyped. If it's a decent connection the loss should be negligible.

Have it your way, I'm just trying to help out. It's YOUR set up. Me, I've been there done that so I know better. I get SWRs of 1:5 with an adapter on my transmit lines, 1:3 without it. Maybe not enough of a difference for you but I prefer to keep mine as low as possible. There is a difference, no matter how small, like it or not.

Have fun!

Manny
 

chris480

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Hey guys still wondering where to buy one of these, and how much the are? Does Radio Shack carry something like this I can use?
 

mancow

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No need to get worked up about it. I'm just saying that I haven't noticed a difference but maybe I got lucky. Now, I wouldn't want a whole train of the things on there either but I was referring to the setup discussed in this thread. (The hi power preamp). I'm saying that I think that the box pushes enough power that an adapter or two probably won't be noticeable if you are using just to re-transmit stuff to a nearby receiver.

If it's being used as a regular preamp near an antenna then I would try to stay away from any and all adapters as well. I seem to have more problems with them physically failing, as in breaking apart. The RadioShack mini uhf to PL-259s are the worst. They will shear off with the slightest pressure.
 

N1SQB

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Not worked up at all Mancow!
Just pointing out that it is YOUR set up and that I dont want you thinking that I was trying to tell you what to do, thats all brother.... Yeah, I do see the unit does push some good power. I was just thinkin that with less adapters, you might be able to squeeze a few more feet out of the range. If 20 ft is enough for what you're doing, cool...I am lucky in the sense that I get good enough reception on my digital 800 systems that I just neeed a good back of the set antenna. Of course, being on a high point, 475ft above sea level, near the coast helps a lot too...LOL Good luck with it......

73

Manny / N1SQB
 

andrewccm

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I now have 2 of these preamps.. Thinking about selling one... I haven't had the best luck with my own setup (still trying various methods of powering and antenna combinations), but I do know that the amps work. If anyone wants to fiddle with one, I'll be happy to sell it for $30 + shipping.

I realize this should be in buy and sell, but since it's such a specialized product and within the only thread discussing such a device, I thought it might be appropriate here.
 

Signal3and2

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Do you suppose that it would have any negative effect on any other bands like VHF and UHF? I'm struggling to pull in an 800mhz system on my 2096 and this could be the key. However, my VHF systems I listen to are great and need no boost. I guess I'm just wondering if using one of these permanently inline between the antenna and scanner would mess up the VHF receive?
 

LarryMax

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If 20 feet isn't enough for you, you can always use wireless headphones. Of course when something good comes over the radio I find myself running to the scanner to see the display/who it is.
 
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