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Sunhans 5.8 Ghz Amplifier - Attenuator Question

Discussion in 'Phantom 2 Vision + Discussion' started by LSD4me, Aug 17, 2014.

  1. LSD4me

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    Hi all,

    I am in the process of upgrading my 5.8 Ghz (Control) signal. I have purchased a Sunhans 5.8 Ghz amplifier that accepts an input of 100mW (20dBm).

    My question is from an attenuation point of view. It is my understanding that in FCC mode, the Phantom Controller will pipe out 100mW in power. But my concern is whether there is ever a point where the controller may output even more...I don't want to blow out the amp so I think I need to put an attenuator on the input side of the amp to keep the input power at 100 or below.

    My problem is that I am not an engineer and I barely wrapped my head around what I just typed above ;)

    Can anyone please shed some light and possibly recommend a specific type of attenuator that will suit this purpose....(if required at all)

    Thanks!!!
     
  2. tizzl10

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    I have been running my sunhans 5.8 amp without an attenuator in FCC for a couple of months now and have had no issues.
     
  3. LSD4me

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    Seeing as how the amp will boost the signal at a factor of 10, do you think it would be safer to put the controller in CE mode, since the signal will be boosted anyway? If I do put it in CE mode, will that have an impact on the range when compared with FCC? The amp will boost the signal either way, but just wondering if the input power difference between CE and FCC will directly affect the output from the amp...Hope this makes sense...
     
  4. tizzl10

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    Im not sure, but that amp is phenominal. I will try out the performance in CE mode tomorrow and report back.
     
  5. sidebox

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    I mean... it seems clear that you'll get less out output from the amp if you are inputting less power. I'd expect a hit on distance if using CE mode.
     
  6. LSD4me

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    Ditto...I'm just not sure if the amp will just juice up the input signal (as much as it can based on what it is), or be able to put out a guaranteed 1000 mW no matter what...
     
  7. PVFlyer

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    I haven't used the amp SH58Gi1000. Per the specification, the amp is (1) Output Power: 1000mW (30dBm), (2) Transmit Gain: 16-19 dB. The P2V+ 5.8G transmitter CE mode is 25mW (14dBm) and FCC mode is 100mW (20dBm).

    Based on pure mathematics and the lowest gain assumption, CE mode is good enough to juice up all output power 30dBm of the amp (CE: 14dBm + Transmit Gain: 16dB = 30dBm). In reality, there may have some attenuation (easily 1-2 dB or more) on the pigtail cable, patch cable and RP-SMA jacks depending on how you mod it.
     
  8. LSD4me

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    Response like a champ! Makes complete sense :mrgreen: ...Ill set it to CE as FCC seems a tad much.
     
  9. ToThePoint

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    In human language:
    The booster boost up the signal 16-19db. It doesn't matter what it gets in the input, it will raise it with 16-19db on its output.
    So if the input is 14db ( CE mode ) and the booster provides +16 ( it could be 19 but thats due to the tolerance of used components in the booster ) then you have 30db or 1w power.
    If you set the RC to FCC you begin with 20db+16 = 36db or 4w power. ( Almost doubling the range )
    Then you have the antenna and there they note it in DBi.
    Let say its on CE mode: 14db fron the RC + 16 from the booster and 6 from the antenna gain, 14+16+6= 36db total gain or 4w output.
    That same antenna on a FCC setting provides a additional 6db and it make a 42db or 30w output.
    Its clear that not only the RC output ( CE or FCC ) effects the total range, also the antenna and its specifics.

    Based on this knowledge it clear that the range is effected.
    A lot is due to losses in connectors/cables, and to be sure what the booster sees on the input you have to use a power meter.
    Be warned that with use of the booster, the antenna is playing a really great role into the setup.
    That antenna has to be as close to 100%. If a wise guy uses the coke can mod they end up with smoke-signals like the Indians did. I guess the V+ is to modern to understand that.

    My personal experience as fully licensed HAM radio OM for 20 years now with boosters up to 500 and 1000w.
    The losses ( DB ) till it gets in the booster input makes that you probably aren't getting a 20db.
    So FCC can be used but if you are uncomfortable with that its wise to set it to CE. It saves on power drain also.
    I tested the provided so called 6dbi onmi antenna that came with the booster ( yes i have the sunhans as well ).
    It isn't what its supposed to be.
    If you have a rp-sma connector on you RC test he range of that antenna without the booster.
    It didn't preform better as the stock one from DJI, and that only a dipole antenna ( 2,15db ).
     
  10. LSD4me

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    Another champ response! :mrgreen: Makes perfect sense...

    I am pretty sure I am not getting 20db input into the booster, as i didn't take into account any attenuation based on my cabling / connectors...So based on that rationale, FCC would be an OK input...

    So now I have 2 questions....

    1) If the rating on the amp is 1W/30db output, and we are starting with ~20db input into the amp, the output should be ~36db...How does that extra output play with the amp if the max output is rated at 30db? Will the amp actually put out 36db or 30db?

    2) The other question is about testing the actual values...I have a meter but am unsure which settings I need to put it on to test the DB / mW output from the RC, and the output from the booster. I am assuming the negative is the casing around the RP-SMA and the positive is the pin in the middle. Can you please let me know which settings I need to look for on my meter to test the above.

    TIA!
     
  11. ToThePoint

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    Your a good student. I have to check in the specs to answer.

    Ok the output power is 1000mW ( 30db )
    It could be that there is a power divider ( attenuator ) @ the entrance because most stuff to be boosted gives 20db ( 100mW ).
    The designer has to take in account the max specs of the final booster stage setup. The max is the max.
    Also you have losses into the booster itself.
    To give you a exact answer you have to have the data sheet and or schematics of that booster.
    Anyway the specs say its 1000mw max.

    You need a special meter to measure microwaves. And they cost a lot of money, seen amount of US$ 10.000 but that was for a spectrum analyzer.
    What you need is a power/ SWR ( standing wave ratio or something) meter for 5.8Ghz.
    The most important component is a ..... ( forgot the name, i'll get back on that ).
    One for 2.4Ghz is around US$ 88 and redot is the manufacturer.
    The following link is ment as a reference: http://www.aliexpress.com/snapshot/6176051207.html
     
  12. LSD4me

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    Understood. I don't think I need to go as far as getting spectrum analyzers, as it wouldn't matter anyway...max is 30dbm...

    Ill post some results for range between the regular setup and then with the amp in the mix...

    I should have the amp delivered today so ill try to get it out there and flying and post results shortly.
     
  13. ToThePoint

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    Tested my amp yesterday.
    On CE it uses 0.9 / 0.10 A and on FCC the booster takes 0.14 A.
    I had to know because i am going to use a 7812 for the tension stabilization of 16,6V out of 4x3,7 li-ion batteries.
    I can use the 7812 without cooling.
    That something you ca test with the DIY multi meter and i advice to do so.
    Measure the mA usage so you can determine afterwards if you have issue's and want to know if the booster has blown up.
    Also you can calculate the power output.
    Measure what its consumes when the RC is off. Then measure what it uses when the RC is on.
    Substract the 2 and multiply with the tension provided.
    If you use the stock AC adapter it gives 12v so let calculate.
    I had with RC off 0.05mA and with the RC on 0.14 mA. Thats 0.09mA more when on. 12 x 0.09 = 1.08W
    Do the same with your RC .