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 Subject :Amplifier Question.. 2012-06-07- 15:24:11 
kc9mnl
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Joined: 2012-05-24- 23:37:34
Posts: 5
Location: 

Hello all,

I finally installed my 15 db antenna and a 4w amp. I'm not getting the type of signal that I expected even in line of sight. When I tested everything before the install I was getting a Signal of 10 to 14 on my wardriving app. Now after the install I have a signal of 68 to 78 only 40ft away LOS. The power light is on the amp and the TX light flickers. When I tested on the ground I didnt have the lighting arrester yet.  I have a wrt54gl pigtail to the dc injector, 30ft of lmr400 to the amp, 2ft lmr400 to lightning arrester, 2ft lmr400 to antenna. The antenna is here http://www.amazon.com/gp/product/B0046CBR3W/ref=oh_details_o02_s00_i00 . The amp is http://www.amazon.com/gp/product/B003B09GBU/ref=oh_details_o03_s00_i00 .

Lost,

Steve

KC9MNL
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 Subject :Re:Amplifier Question.. 2012-06-09- 19:40:21 
kb9mwr
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Joined: 2010-10-06- 23:04:25
Posts: 54
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Any chance you can pop the cover and take a picture?
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 Subject :Re:Amplifier Question.. 2012-06-09- 20:16:27 
kc9mnl
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Joined: 2012-05-24- 23:37:34
Posts: 5
Location: 

I think the amp is dead. I ordered 2 complete sets of all the above equipment. I was trying to setup a link between two points. The TX light on the inverter and amp on the mast do not flash nearly as often as the one I haven't installed as of yet. So I got an RMA for the defective one. I just have to crawl my butt back up on the roof to replace one with the other. I'd open it up if I couldn't send it back. Sorry
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Last Edited On: 2012-06-09- 20:16:49 By kc9mnl for the Reason
 Subject :Re:Amplifier Question.. 2012-08-02- 15:51:40 
KD4E
Member
Joined: 2012-07-29- 13:39:05
Posts: 55
Location: Nevils in SE-Georgia, USA
 
We plan a trip that could take us through as many as 10 Mesh-equipped cities. The amp you listed is no longer available via Amazon (I'd actually prefer a different source). I spotted this b/g (not n) 2w model (half the power) for $99. http://www.amazon.com/Alfa-Outdoor-802-11b-Booster-Amplifier/dp/B002R1FXU2/ref=pd_sim_misc_1/177-6404116-6697846 Is that price about what one should expect? What are the minimum specs I should search for, please? Perhaps MCMelectronics or Electronic Goldmine or one of the other surplus houses might have something suitable? Thanks!
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 Subject :Re:Amplifier Question.. 2012-08-02- 16:08:17 
KD4E
Member
Joined: 2012-07-29- 13:39:05
Posts: 55
Location: Nevils in SE-Georgia, USA
 
Would you recommend this antenna w/ mag mount for mobile use? http://www.amazon.com/Booster-OMNI-Directional-High-Gain-Screw-On-magnetic/dp/B0039ORBLK/ref=pd_cp_e_3 I did not see another one that came with a mag mount. I do have a mag mount with an N-connector, so I could use something with more gain that is larger and uses that type of connector. It will be on top of a rented van for the trip so it needs to be a tilt-over, or somewhat short, to avoid being damaged by hotel overhangs, branches, etc. Thanks!
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 Subject :Re:Amplifier Question.. 2012-08-03- 15:02:29 
KY9K
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Joined: 2012-07-07- 23:39:07
Posts: 23
Location: Roy, WA
I can't tell for sure, but the pictures seem to show an RG-58 sized cable on that antenna. The loss of the cable may well nullify the gain of the antenna. While an amp would improve your transmit power, it won't improve the power of the mesh nodes transmitting back to you. If I'm deploying amps, I've always put amps on both sides of a link. -Brian/KY9K
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 Subject :Re:Amplifier Question.. 2012-08-06- 23:57:06 
kc9mnl
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Joined: 2012-05-24- 23:37:34
Posts: 5
Location: 
I'm sort of new to this whole thing so I don't know what to recommend at this point. I know that l-com.com has amps there too although they seem more expensive. I'm not sure that higher prices translates to better products though. As far as the rg-58 cable I would be curious to find out what the length of it was. You might be able to extrapolate the DB loss if you knew the type and length of cable. 12 ft of cable might not be too bad. Also some of these amp have a pre-amp on them...might help a bit.
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 Subject :Re:Amplifier Question.. 2012-09-03- 08:17:35 
KD4E
Member
Joined: 2012-07-29- 13:39:05
Posts: 55
Location: Nevils in SE-Georgia, USA
 

These seem a little pricey at $154. but would they be appropriate for mobile use? http://www.rflinx.com/products/amplifiers/2400/ca/


Or maybe this 1w bi-directional amp for $89.95?

http://www.radiolabs.com/products/wireless/wre1000mw.php
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Last Edited On: 2012-09-03- 09:11:03 By KD4E for the Reason
 Subject :Re:Amplifier Question.. 2012-09-03- 12:25:39 
KY9K
Member
Joined: 2012-07-07- 23:39:07
Posts: 23
Location: Roy, WA
Per the Times Microwave calculator at: http://www.timesmicrowave.com/cgi-bin/calculate.pl 12ft of RG-58 has 3dB of loss at 2400MHz. For receive, no amplifier can provide more S/N than is present on the input. It will simply amplify both signal and noise to a higher level. While you will get a higher signal level, the S/N won't improve. Unless all the mesh nodes are equipped with amplifiers, you'll end up with plenty of transmit power, but won't be able to hear the other mesh nodes talking back to you. Better to put the gain into the antenna and locate the node as close to the antenna as possible. Something like this: http://www.fab-corp.com/product.php?productid=3093&cat=250&page=1 will give you 7.4dBi of gain in a compact (19inch) package. If you go with the spring mount, you'll have a good solid mobile antenna. If you want it movable between vehicles, perhaps mount a waterproof box with the node inside and the antenna on top with one of the 3-4 large magnet mounts intended for mobile HF antennas. You'll then just need to bring in power and Ethernet (possibly via a single cable). That will minimize your lossy coax run and likely give the best performance. KY9K/Brian
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