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DS1192
join:2010-07-16
La Crosse, WI

1 edit

DS1192

Member

Grid Antenna Issue - Maybe?

So when I first bought the 2.4Ghz grid from L-com and used it I could get about -77dbm to -83dbm with it just connected to my modem. Now I can't even get below -100dbm. I tested it today because I was using a revision 6 cyfre amp, and was only able to achieve -83dbm. Which doesn't make sense, considering I was able to beat that without it once. I have had the grid for over 2 years I would say. So can these things lose power? Is is possible that the revision 6 amp killed it considering it doesn't output 2.4Ghz? It seems like I have a bad antenna.
DS1192

2 edits

DS1192

Member

So I tried my new 598U and plugged it in, it's a back up, no difference in signal. I tried my old Cyfre amp w/Splitter and signal was -91dbm, with the revision 6 amp it's -83dbm. I used the Cyfre amp w/Splitter for a long time without any issues. When I first purchased the revision 6 amp I was able to get into the low -67dbm level. But since then I have been losing signal slowly. I think the most logical and likely reason is that since the new revision 6 amp didn't require a splitter the grid was getting fed an amped 1900mhz signal which is not 2.4Ghz which has damaged the antenna. I only wish I would have known before hand, to prevent this. Considering this, my next antenna will be a 12dbi 1.9Ghz panel antenna. If anyone has an Andrew PCS grid I would be willing to maybe use that instead and purchase it.

I would also like to know if the revision 6 amp was damaged by this, I am now using the splitter on the revision 6 amp because of fear of it getting damaged. I am now at -85dbm. It seems I keep going 1 step forward and 2 steps back.

I am not worried about the grid antenna being damaged, but I really just want to know if the revision 6 cyfre amp was un-affected. I am guessing that it has not been considering it was okay by many forum members. And it's still making my connection go from -100+dbm to -83-85dbm. If the antenna was new and I was back at -83dbm with just the antenna, the amp would surley be getting me back down into the low -70dbm or below. So I think the amp is fine. Also, my speeds don't seem to be any worse but I am a perfectionist and want the setup to be as good as possible.
Max Signal
Premium Member
join:2008-03-07
Buffalo, NY

Max Signal

Premium Member

You do not need the splitter . But you should be using a frequency correct antenna not a 2.4 antenna . Close only counts in Horsehoes and hand grenades !

dib22
join:2002-01-27
Kansas City, MO

dib22

Member

said by Max Signal:

You do not need the splitter . But you should be using a frequency correct antenna not a 2.4 antenna . Close only counts in Horsehoes and hand grenades !

quote:
Many people have purchased a 2.4 GHz version to use on a 1.9 GHz (1900 MHz) EVDO network. Mainly due to the lower cost. The 2.4 version will work, the loss is less than one dB with the minor mis-match. Minimal indeed.

»evdotips.blogspot.com/20 ··· nna.html

A spacer will change it from a 2.4 to a 1.9 if your really worried about the one db!
Max Signal
Premium Member
join:2008-03-07
Buffalo, NY

Max Signal

Premium Member

For someone that is such a perfectionist a mismatched antenna does not seem like perfection to me . Could your antenna be misaligned ?( happens over time ) also they might have re-aimed the panels on the antenna tower . Carriers tend to do that from time to time to try and improve their coverage.

xrayman
join:2008-12-09
Kansas City

xrayman to DS1192

Member

to DS1192
Dexter1992, I know you are testing and the signal has changed.
But I want to tell you the L-com antenna is not a complex active electronic device, with many IC chips and other electronics in it. I have take that antenna apart and adjusted the dipole length to better match the Clear/Sprint WiMax frequency. Inside is only the dipole element (two solid copper ribbons) and the cable, very simple solid construction.
If the signal drops off on the antenna I would be looking for a bad cable connector or moisture that has made it into the cable at the connector.
When tracking down signal loss, many time I have found the bad connection to be in the connection for the antenna patch cable inside the modem device.
Just my 2ยข worth of info.
DS1192
join:2010-07-16
La Crosse, WI

2 edits

DS1192 to dib22

Member

to dib22
said by dib22:

said by Max Signal:

You do not need the splitter . But you should be using a frequency correct antenna not a 2.4 antenna . Close only counts in Horsehoes and hand grenades !

quote:
Many people have purchased a 2.4 GHz version to use on a 1.9 GHz (1900 MHz) EVDO network. Mainly due to the lower cost. The 2.4 version will work, the loss is less than one dB with the minor mis-match. Minimal indeed.

»evdotips.blogspot.com/20 ··· nna.html

A spacer will change it from a 2.4 to a 1.9 if your really worried about the one db!

I am using the 1/2 inch spacer. If I recall I started having issues after using the revision 6 amp. Occasionally, I would log into the MBR-1000 to find the signal jumping all over from -80dbm to -100dbm, ec/io being around -10. I figured it was the amp, and if I turned it off and back on, the signal would be back to normal. I am not sure how the new amp determines if you need 800mhz or 1900mhz, but it seems it was amping 800mhz into my grid at times, which probably damaged it. My grid is not out of place, it's locked in and will not be moving. I will be ordering a new feed-horn from l-com, I will report my findings.

Edit - The HG2424G-NF has been discontinued, but a different version has took its place.
Max Signal
Premium Member
join:2008-03-07
Buffalo, NY

Max Signal

Premium Member

Your device tells the amplifier what frequency it needs to amplify . Amplifier cannot determine that and in no way can damage anything !!!
DS1192
join:2010-07-16
La Crosse, WI

1 edit

DS1192

Member

said by Max Signal:

Your device tells the amplifier what frequency it needs to amplify . Amplifier cannot determine that and in no way can damage anything !!!

Well in that case, I have no clue why performance of just the antenna has degraded so much. I guess it's possible the tower was changed or having issues but I would doubt it.
also, L-com said that they don't sell just fee-horns so I will have to buy the whole antenna.

Also, how can we trust that the communication between the amp and modem is accurate?
Max Signal
Premium Member
join:2008-03-07
Buffalo, NY

1 edit

Max Signal

Premium Member

Because that is how it is designed . Any number of issues can cause your loss of signal . But one thing I have learned in my years of selling and doing support on these amplifiers . They either work or they don't work . No degradation or part way or intermittent performance issues . When They are dead they are dead . No part way . These amplifiers were designed in conjunction with Motorola and Cellular carrier network engineers . They were the only direct connect amplifier that were carrier approved . And when the carriers test your stuff they are a lot tougher than any FCC testing. As Xrayman suggested you should check all your connections . Any compromised connection could be causing the problems you are describing. Even your RF port on your data device could be wearing out and causing loss. At times it seems you are just looking for problems and something to blame even if your overall performance is still good . Also I hope you are getting your RSSI readings with your device inserted directly in a computer utilizing the carriers software . As router RSSI readings are not even close to accurate.

If you want send in the amplifier I will connect it to my HP-Agilent spectrum analyzer to make sure it is amplifying properly on 800 and 1900.
DS1192
join:2010-07-16
La Crosse, WI

DS1192

Member

said by Max Signal:

Because that is how it is designed . Any number of issues can cause your loss of signal . But one thing I have learned in my years of selling and doing support on these amplifiers . They either work or they don't work . No degradation or part way or intermittent performance issues . When They are dead they are dead . No part way . These amplifiers were designed in conjunction with Motorola and Cellular carrier network engineers . They were the only direct connect amplifier that were carrier approved . And when the carriers test your stuff they are a lot tougher than any FCC testing. As Xrayman suggested you should check all your connections . Any compromised connection could be causing the problems you are describing. Even your RF port on your data device could be wearing out and causing loss. At times it seems you are just looking for problems and something to blame even if your overall performance is still good . Also I hope you are getting your RSSI readings with your device inserted directly in a computer utilizing the carriers software . As router RSSI readings are not even close to accurate.

If you want send in the amplifier I will connect it to my HP-Agilent spectrum analyzer to make sure it is amplifying properly on 800 and 1900.

How is -100dbm with a grid good performance? I understand the history of my setup and if the change was at the tower I would not be able to still get 1-bar of cell service on my phone with a change that drastic. At this same time I could pull almost 100% signal with my grid 2 years ago. It's just obvious that something caused the antenna to be damaged. The newest edition to my setup was the revision 6 amp, so that was my first guess. You say they either work or they don't, no intermediate issues, well that's not my findings, and I can re-call may others having similar issues with the amps. At times it seems like you are just trying to make sure your amps are not getting negative feedback, which I can understand. I am just reporting my findings and speculating, and asking for forum advice. I don't need someone analyzing me from the internet, thanks. Also, you say router readings are not close at all? I find them to be 100% identical with the MBR-1000 and Sprint Smartview, because the MBR-1000 gets it's readings from the modem the same way Smartview does.

Now that I know the modem determines the frequency, I will just use the splitter as I don't trust the communication. All connections are fine. Again, just saying my findings.
Max Signal
Premium Member
join:2008-03-07
Buffalo, NY

2 edits

Max Signal

Premium Member

An amplifier cannot hurt an antenna . There is no power to the antenna !! . The amplifier just amplifies the signal given to it from the antenna .RF does not have any power to destroy electronics in the way you are speculating. Sorry but you have no idea what you are talking about !! Over 100,000 of this model amplifier have been sold to date . And nothing like this has ever been reported . It is against all the rules of physics and RF what you are trying to imply . You need to look elsewhere the amplifier is not the issue . I still wonder if the panels on your tower a have been reconfigured to facilitate better coverage by the carrier , They often do this . But think what ever you want .

You should take your panel antenna out of the whole scenario . Test the amplifier with Just the mag mount antenna that came with it ( just make sure the antenna is on a proper ground plane ) . See what that does also see if you can get another sprint device to test with your set up. Like I said before the RF port on these devices can also get compromised and adversely effect your results . You have not tried to eliminate any variables before drawing your conclusions . At least be thorough before drawing any conclusions. A cable or connection somewhere could be compromised without it being apparent to the naked eye.
I will say it again , send in the amplifier if you dare and we run thru a battery of testing on the HP- Agilent spectrum analyzer.
DS1192
join:2010-07-16
La Crosse, WI

3 edits

DS1192

Member

If they moved I could not get any signal from in my house with a cell phone(VM) if that was the case. It was my understanding that incorrect amperage into an antenna would damage it. Anyway, I will continue to look.

Edit - I did test a second 598U, the modem is not bad. I used the mag mount antenna on top of my car and got -78dbm, I used it on a separate made ground plane which is galvanized steel 12 inch by 12 inch on a pole above my roof, signal was -97 to -100dbm. Which I was surprised because I thought that should have been a lot!!! better than that. I figured the ground plane was just not big enough compared to the top of my car. Now if you rule out the ground plane, then I could maybe see faulty cables, but since I haven't touched them in forever, and all the connectors are fine, I don't see that being the issue. How about this, I will test the amp and just the mag mount antenna bypassing my current LMR-400 cable to rule it out. I will test the mag mount on my car, and on my separate ground plane. If I can get into the low numbers then that will say something.
Max Signal
Premium Member
join:2008-03-07
Buffalo, NY

Max Signal

Premium Member

You could still get signal to a phone !!! the antennas on phones are not directional and do not have to be pointed directly at a tower ! Remember panel antennas are directional . Movement of a panel on a cell tower will directly effect the performance of them. And your understanding of RF and amperage sent to an antenna is just not true, whoever told you that was feeding you misinformation.
DS1192
join:2010-07-16
La Crosse, WI

1 edit

DS1192

Member

Sorry, check my edit. But I will have disagree with the phone statement considering my findings with the mag mount. Trust me, my grid was pointed correctly.

Will test tomorrow.
Max Signal
Premium Member
join:2008-03-07
Buffalo, NY

Max Signal

Premium Member

You used the amplifier and mag mount in your car and got a -78 . Yet you used on your roof with the LMR400 in between and got a -100 . The amplifier is working fine . Simple deduction says your LMR400 is compromised . Sometimes everything looks fine with a cable and it is compromised .

jsme304
join:2009-10-16
Lampasas, TX

1 edit

jsme304 to DS1192

Member

to DS1192
Dexter...
When I left my wireless and 2.4 Ghz grid antenna,
my modem was showing a 100% signal and readings of from -65dbm to -70dbm and Ec/Io 0f -1 to -4dBm... this with no modification w/ a spacer and 6 miles from cell tower.
And on top of that, a direct lightening strike, where the charge came out of the 30 ft. worth of RG 58 cable, in the house, while the disconnected cable end layed loose from the cyfre amp.. I witness this. the sys had surge supressor inline. After this lightening issue... we finally changed to Exede, to get away from the high mounted antenna, to the dish that is 5ft off the ground.

So I really doubt it is the antenna..
Jim_in_VA (banned)
join:2004-07-11
Cobbs Creek, VA

Jim_in_VA (banned) to DS1192

Member

to DS1192
Looks clear to me it is not an amp issue. Check the connectors on the LMR400 for water/moisture intrusion. You do have those sealed yes?
DS1192
join:2010-07-16
La Crosse, WI

DS1192

Member

Sorry guys, I was swamped today so I could not test. Max, the ground plane I made is not as big as the top of my car so that's why it was so low I believe. I could actually bring the amp up to the grid and test it. But note when I tested it on my car that was months ago.
DS1192

2 edits

DS1192

Member

Okay, sorry I am late, but here are the findings.

Using the 598U, connected to the amp, then the 2.4Ghz grid antenna with 1/2 spacer mod connected to the amp, with LMR-400 cable in-between I could only achieve a low of -88dbm. Garbage to say the least.

I then took everything on my roof to eliminate the LMR-400 cable. I was able to get -78dbm. Note: -78dbm was what I was able to achieve without the amp 2 years ago, with LMR-400 cable and the grid directly connected to 598U.

I also, tested the mag mount which was terrible, -95dbm, ec/io fluctuating to -9. At this point unless I want the to put a ground plane the same size as the top of my car on my roof, the mag mount does not help at all. Should not even be included in the kit unless you are traveling in my opinion. It just doesn't perform well in low signal areas at all.

So removing the LMR-400 out of the equation I gained 10dbm, which I think just shows the loss added by the cable. I got rid of the amp, and connected the grid directly to the modem, to get about -91 dbm.

It's clear to me that either, the tower panels did move, the grid antenna is dead, or an issue with my 598U's antenna adapter cable.

At this point, I will maybe buy a panel antenna and amp it.

Here are my antenna options:

- »www.ebay.com/itm/24-Rect ··· 66wt_248

- »www.l-com.com/item.aspx?id=20253

That 1800-1900Mhz grid looks a lot better than the one I currently have.
Max Signal
Premium Member
join:2008-03-07
Buffalo, NY

Max Signal

Premium Member

you are so wrong about that Mag Mount . Everyone raves about that antenna It outperforms everything on the market Here is an independent review.
»www.jackdanmayer.com/Fil ··· Test.pdf
This guy is the top tech guy in the RV community. I have no idea about your testing methods but you must be doing something wrong
DS1192
join:2010-07-16
La Crosse, WI

DS1192

Member

Well it performed amazing when using my car as the ground plane, using my 12x12 inch square galvanized steel ground plane it didn't even barely make a difference.
Max Signal
Premium Member
join:2008-03-07
Buffalo, NY

Max Signal

Premium Member

Well was your ground plane aluminum or stainless ? Aluminum and stainless steel do not work . because it works great on 8 x 8 metal ferrous surfaces , 1000's of users love it , also must of been something wrong with your LMR400 as 10 db loss was far too high.
said by DS1192:

Well it performed amazing when using my car as the ground plane, using my 12x12 inch square galvanized steel ground plane it didn't even barely make a difference.

DS1192
join:2010-07-16
La Crosse, WI

DS1192

Member

Yeah, it truly confuses me. I believe it's steel, the only difference is the size and it's about roof level. Also, I figured that was a bit much for cable loss. Maybe it's a combined issue, the grid antenna and the cable are just getting bad. At this point, I will try some things. If I find anything I will add it in.

The amp connected directly to the grid should have been below -79dbm, based on past results when using it. So that leads me to believe the antenna isn't functioning properly. Also, I have a new 598U and that showed no difference. The only things I can think of is the adapter cable for the 598U, or the tower actually did change here in the last few months. I am buying a new antenna to test.