Any real amps out there?

powrby4d · EVDO Fledgling Joined: 24 Dec 2007 Posts: 20

Does anyone know if there is an amplifier that will actually transmit the amount of RF power advertised? I just found out that the 1-watt amp I spent a couple hundred bucks for actually is a puny .5 watts, and the popular competing amp advertised as 2 watts at 1900 MHz is actually less than 1 watt in real life. The advertised numbers commonly seem to be bogus combinations of using the figures for only one band, or total of both bands, or using EIRP or ERP based on an assumption of the recommended antenna gain (e.g. 3dB gain = 2X actual watts) instead of just honestly listing the actual RF transmit power. If you go to https://fjallfoss.fcc.gov/oetcf/eas/reports/GenericSearch.cfm
and look up the amps by the FCC ID for the device the advertised claims don't hold up.

Does anyone make an amp that actually transmits at the actual legal maximum of 2 watts at 1900 MHz at unity before applying any higher antenna gain or other cleverness to the numbers?

n6gn · Posted: Mon Jul 21, 2008 8:07 pm Post subject: Re: Any real amps out there?

powrby4d · EVDO Fledgling Joined: 24 Dec 2007 Posts: 20

Thanks for the reply. I'm counting on exactly the behavior you describe when adding a high gain antenna such that the outcome of the combination of sufficient antenna gain and sufficient transmission power capability results in exactly the correct amount of negotiated power under less-than-optimal conditions -- no more but no less. In my case the conditions are minimum 7 miles (closest tower) right at the horizon through dense foliage. The problem at this point is mostly on the uplink, and what I noticed is that with the advent of Spring foliage the uplink performance on EVDO Rev A went from sometimes bad to always awful, and replacing the somewhat poorly-positioned 3dB booster antenna with a slightly better 7dBi antenna and the amplifier did not overcome the performance degradation. The need for a better (and better-positioned) antenna was obvious, but the lack of improvement with the added amp considering that downlink performance was OK led me to research why I did not see more improvement on the uplink with both a better antenna and an amp - thus the discovery that the amp was only operating at 500mW, and that other amplifiers I looked into were using some interesting interpretations of the actual transmission power. What I am hoping to ensure is that if the negotiated power levels require the card to raise transmit power that the combination of a better antenna and more capable amplifier will be sufficient to get a consistent signal to the tower without the major latency fluctuations I have observed.

n6gn · Posted: Mon Jul 21, 2008 9:04 pm Post subject:

Well, my point about the negotiations is essentially that once the path between cell and device- inclusive of antennas and cable- is good enough on the downlink, the system design won't let the handset run significantly more power and additional capability in the transmitter, whether in the card or external, won't even get used.
Did you actually *measure* the RF output of the external amplifier to have max'd out at 500 mW and thus to be entering distortion?) or are you just reading the package? As a an alternative to measuring the RF power, you might look at the DC input current with a fast responding device like as oscilloscope.

n6gn

powrby4d · EVDO Fledgling Joined: 24 Dec 2007 Posts: 20

Now to find an amplifier that actually does what it say it does such that the required transmit power for the uplink is there if called upon.

I think that the fact that many people report improvements with their amplifier of preference supports your statement that the amplifiers rarely approach their advertised power levels - otherwise creative advertising of maximum power levels, particularly as it applies to actual discrepancies between amplifiers, would be more apparent to end users.

powrby4d · EVDO Fledgling Joined: 24 Dec 2007 Posts: 20

I was going by the difference between the advertised 1W RF power output @1900 MHz versus the FCC tested power rating for the amplifier which was RF transmit power to the antenna of 500mW @1900 MHz with a manufacturer recommended antenna gain of 3dBi for 1W EIRP.

Having my own test equipment would be far better - in absence of same I have to take the word of the FCC grant for the device.

powrby4d · EVDO Fledgling Joined: 24 Dec 2007 Posts: 20

It is true that I am making a big assumption that when uplink performance goes in the toilet and throughput fluctuates wildly that the tower is probably calling upon the card adjust transmit to a level that it is incapable of pushing through 7-16 miles (depending on which tower) of trees, and I am hoping that either or both of a better antenna and additional power if needed will allow the card to do what the tower is requesting.