I thought of soldering 2 Antennas ( the first one is connected to CHAIN 1 & the Second antenna is connected to chain0 ) but actually its confusing to me when I see 3 aluminum metal connected to the PC Board internally at the circuit and the one which also confuses me more that the antenna is between 2 negative points grounded that can produce 2.5dB of GAIN! or how much gain we can get at each antenna internally ( default antennas ) .
My target is to push CHAIN 0 ( which is by default 2.5dB ) to 10dBi as an external + chain 1 which has already MMCX cnnector but I already have soldered a cable and replaced the MMCX port with SMA MALE to attach the antanna withthe cover of RB571U-2Hn. I want to solder a cable at the positive , negative chain 0 and the end of the cable would be attached as SMA Connector and then we can use 10dBi Antenna which has SMA Female .
Should I email MikroTik Support to get help on this product .
The software shows TX Power as 27dBm which seems to be 500mW so I thought maybe every chain has the half 1 watt TX Power but the website said it has 30dBm. I thought of soldering a very short cable to the chain 0 that has SMA connector attached with the cover just to avoid using MMCX Antenna and this way the customer would pay less if he wants to boost his signal since I have an idea of covering most area “hotspots” but te PC Board has only 3 PIF antenna and each small PIF Antenna has 2 legs connected to the same negative side of the board which we call it ground!.. I also need to find the positive transmit line on the board to have an External Connector of chain 0.
I already saw the 2 lines ( P , N ) of antenna-b . Where is the ANtenna A that has chain0 .
Could you please amos explain to me or if I could send an email to support to get help .
I need to order at least 500 pcs after I complete this job.
Thank you Amos for the link you gaved to me and I have already saw it and I have noticed the one you qoute it to me but still needed your confirmation about what I have attached .
every chain is on ground points .. Is it possible to have an antenna from negative only ?
so you want me to solder the cable of the Omni 10dBi antenna directly on the 2 legs of the chain 0 but I guess it wont work because the cable needs Positive which has the Transmit Power at chain0 (not chain1 which has MMCX Port ) + Negative.
antennas don’t gave positive and negative connectors. by modifying the device this way, you will most likely burn it, because it was calibrated with these specific antennas. if you need external antennas, use RB711 or such devices. or - RB751 has an MMCX connector, use that.
I have already removed the 3 PIF Antennas and replaced them with short cables attached SMA connectors to the case and finally it is working as I expected and for sure as i noticed the small pif antenna’s legs are between groud and positive (tx) . Yes I know it would be burn if i have mistaken with those 2 very small lines on PC Board but I have succeded .
I really like this product . I wanted to use chain 0 with chain 1 to get 300 Mbps.
Does that mean if we have only used chain-1 with external antenna , it would give only 150Mbps rate! but if we are on chain0 + chain1 then it would reach 300Mbps with external antennas such as 3 x 10dBi.
Can you confirm that Amos ?
I have choosed this product because it is cheap for our customers & why the software shows 27dBm but website says 1Watt ?
My attached picture is totally wrong but sorry I couldnt have time to fix it anyway I still do not know what are you planning to using your pictures above ?
I guess you want to extend your coverage but the confusing thing is why you had to solder a jumper cable .. It is not safe because this jumper that you had at the picture is related to “Power Over Ethernet” and also I still dont know why you had to remove the external MMCX port from the board .
Let me explain to you something .. This board has a chip 802,11b/g/n and it has 2 outputs ( dual chains ) connected to 2 x Power Amplifiers named as LX5518(MSC5518) that has Power Gain 30 dB & if you supplied it with 3.3v then youll get tx power 27dBm or if you supplied this PA with 5V then youll get a maximum TX Power 28dBm so since we have 2 x Power Amplifiers which is limited in the software 500mW then each PA connects to a Switch for TX / RX .
If you really want 1watt then use the default PIF antennas . I already planned to remove the PIF antennas which has 2.5dB and put 3 x small pigtails with SMA connectors just to use 1 watt tx power + to have a higher antennas and I am forced to use 3 x 10dBi antennas but this solution is for HOME which means INDOOR not outdoor.I guess you are planning to use it for outdoor! anyway I wouldnt think like you because what you need is RB711X.
Regarding the PIF antennas , I am sure that the first antenna which is next to MMCX Port is the [ ANT.A - chain 1 TX & RX ] you can test it because I have already tested it !! so the remaining 2 PIF antennas would be ANT.A chain 0 TX or RX .
I will test it again to make sure that I am correct so Its working like I expected!.
well, that’s the correct one which i had to test it yesterday but what ihave found is that chain 0 is not like chain 1 ..
chain 1 can see more neighbours with a noise floor at “-108 dBm” but chain 0 can see only very few neighbours with a Noise Floor “-98 to -99 dBm” very strange .. The thing is the chain 0 is far from the chain 0 only less than “2 cm” ummm .
My Question is why MikroTik had to keep chain 0 as 2 antennas TX , RX alone . Whats the purpose of using this one ? anyway s long as it is working at mine ( 3 x 10dBi ) Its okay for me but Hope I can use something that can combine TX + RX antennas into one antennas so this could reduce using 3 antennas to 2 antennas … but still getting annoyed from chain 0 .. when i use chain 1 with one antennas then I can see more neighbour and if i choose chain 0 then 3 to 4 neighbours i can see .. very strange and when I use 2 chains together then chain 0 reduce neighbours but it gets more strength not Double the gain which seems to be if we are using 2 x 500mW … we cant say 1 watt unless someone has to explain it to me ?
This is secret fiture RB751u-2hnd POE SERVER
only soldering in this pic you can use POE SERVER DIY
for instaling much radio may need much UTP cable to tower.
i use this to suplay my radio in my tower
just soldering this.. all port support POE… simple and practice
Well , if you really want to use this product for outdoor use then it is so easy.
Just follow my last attached picture then youll be able to use it for outdoor use ..
For Example .. If you want to use it as “AP BRIDGE” then all you need is to work around on ANT700 , ANT702 .. Using this method , it will allow you to transmit and receive using 2 chains with 2 antennas! .. or if you want to use one antennas then you can solder a cable on ANT702 which has TX & RX and then at the software you need to tick only chains1 and untick chains 0 + keep on using “antenna A” .
If you want to setup this product as “AP Client (station)” using 2 chains , then you need to connect cables to only ANT701 , ANT702 and get rid of removing the MMCX Port because this will yield 1 watt using 2 x 500mW .
I know what you are doing with POE but it is not safe if someone got power from the UTP Cable or Power Jack at the same time though this PC Board is protected very well. The only one thing that i dont like in it is the PC Board is not thick like DLINK , TPLINK and other manufactors maybe it will be cheaper for them to work on since they are selling the license of ROS with it.
All that i can say is this RB751U-2HnD is so nice and I am going to order more than +200 PCS.
By the way , I will take a picture of my RB751U-2HnD that I already finished 2 days ago. It has 3 SMA Connectors at the Plastic Case so you can easily attach 3 antennas like Omni 10dBi . AS i said for now im using it as AP Client so I only need 2 antennas .
I wish if there will be another product with 27dBm chain0 , 27dBm chain1 , 27dBm chain2 .. OMG this will race & burn the rock lol .
i am realy realy comfused with antena system.
4 antena in one radio… how to make optimal…
follow this pic from top..
mmcx dual mode (rx and tx) LX5518(MSC5518)
ant 702 one mode rx or tx
ant 700 dual mode (rx and tx) LX5518(MSC5518)
ant 701 one mode rx or tx
please explain with picture..
sukses with mmcx port with external antena by soldering pigtail tplink
setting in winbox.
chain 0 off
chain 1 on
antena mode b…
what happen…??? antena port mmcx work
chain 0 on
chain 1 on
antena mode b
what happen…???
which one work.. ant 700, ant 701, ant 702
MMCX not work because.. i scan network can not found ssid
may be you can explain about this antena mode.
i am realy realy confused. i read manual. but i still confused.
help me. if i understand. may be i can tell to all my friend in forum about this antena.
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POE server
I have been testing and practicing .. and no problem. do not worry. work normal. (radio bm2hp and rb751)
repeater
RB751 I use as a spread. and catch I use radio bm2hp.
I’ve used this radio (RB751) as a catch was not good .. ccq bad. poor throughput. ping is bad. then I turned to catch me using bm2hp. and to spread my use rb751
There’s no need to confuse yourself ..
Hope this picture helps!
The only thing and the easiest way .. to use 500mW .. remove the CHAIN 1 - ANT A and solder the cable pigtail directly . If you want DUAL 500mW to yield 1 watt then you really need to remove the 3 pif antennas and then apply 3 pigtails with 3 external antennas and I am sure it will be expensive for you since you already said MMCX is so expensive .
In our country MMCX Port costs 3$ so if we need to apply SMA cable with MMCX .. Total cost would be 13$ at cable length 1 meter.
I have 3 x 5dBi antennas and I couldnt take a picture of the other board that has 3 x 10dBi antennas .
SO the Middle Antenna has TX ONLY which transmit the signal anyway if you configured RB751U to use CHAIN 0 then the middle antenna will transmit the signal which means your other product that scans .. It will see the SSID! but you really need 2 antennas ! ( TX , RX to use 500mW ) on CHAIN 0 .
but Hope I can use something that can combine TX + RX antennas into one antennas so this could reduce using 3 antennas to 2 antennas 
