Aviat radios don't bond + or - to the chassis. You can run them at -48VDC or +48VDC.
On Mon, Sep 21, 2020 at 10:45 AM Steve Jones <thatoneguyst...@gmail.com> wrote: > So, like on these aviats, my contractor says they're -48v, but the > connector in the radio bonds to ground. Does that mean my whole site has to > have -48v or just radios powered by that particular psu? > > On Mon, Sep 21, 2020, 8:59 AM Ken Hohhof <af...@kwisp.com> wrote: > >> Now if we could get the manufacturers to be less secretive about their >> POE schemes. They mostly want you to use their POE device and don’t want >> to document the pinouts or explain if it matters which side is referenced >> to ground. >> >> >> >> Mostly I find that using a Cat6-POE-APC with the jumpers as set at the >> factory and + and – hooked up per the markings works. Which is basically >> 802.3at. It works with the – side grounded, I suspect it would also work >> with the + side grounded, or neither. I was hesitant to use this on a >> PTP820 but it works fine. I don’t know why they make their POE scheme >> sound so mysterious. >> >> >> >> >> >> *From:* AF <af-boun...@af.afmug.com> *On Behalf Of *Josh Baird >> *Sent:* Monday, September 21, 2020 8:44 AM >> *To:* AnimalFarm Microwave Users Group <af@af.afmug.com> >> *Subject:* Re: [AFMUG] -48 noob questions (mikrotik) >> >> >> >> Yep - great explanation! >> >> >> >> On Sun, Sep 20, 2020 at 4:55 PM Chuck McCown <ch...@wbmfg.com> wrote: >> >> You have a power supply, say a 6 volt car battery. You connect a pair of >> headlights to it with two wires. All is well. >> >> >> >> Now you start building cars. And you are going to wire up the >> headlights. Someone points out that you can save some money on wiring by >> using the car chassis instead if one of the wires. >> >> >> >> You decide to run the positive connection from the battery to the >> headlights with wire and return the current via the car’s chassis. >> >> >> >> Now you have turned a 6 volt electrical system into a +6 volt system. If >> you reverse the battery and connect the + side to the chassis and run the >> wire from the negative post to the headlights , it will still work fine. >> The headlights don’t care. Now you have a -6 volt electrical system. >> >> >> >> The headlights don’t care but the radio does. Most radios expect the >> chassis to be negative and their power wire to be positive. You can >> “float” the radio by mounting it on an insulator and connecting its power >> wire to the car’s chases and the chassis of the radio to the negative wire >> going to the battery. A bit dangerous but I have had to do this at times. >> >> >> >> Oh, and the car is an early VW. >> >> Sent from my iPhone >> >> >> >> On Sep 20, 2020, at 2:19 PM, Steve Jones <thatoneguyst...@gmail.com> >> wrote: >> >> >> >> I still cant comprehend any of this. I'm just dumb when it comes to it >> >> >> >> On Sat, Sep 19, 2020, 2:51 PM <ch...@wbmfg.com> wrote: >> >> Yes. >> >> >> >> *From:* TJ Trout >> >> *Sent:* Saturday, September 19, 2020 1:48 PM >> >> *To:* AnimalFarm Microwave Users Group >> >> *Subject:* Re: [AFMUG] -48 noob questions (mikrotik) >> >> >> >> It's just a simple 48 to 12v converter to feed the mikrotik. I tested >> with a ict +48 supply and the 12v comes out fine, I'm 99% sure it will work >> on the wood bench, and about 90% sure it will work in a rack. >> >> >> >> If it was true -48 I would assume the + terminal would be bonded with >> chassis ground? >> >> >> >> On Sat, Sep 19, 2020, 12:45 PM TJ Trout <t...@voltbb.com> wrote: >> >> I think some of my devices have the chassis ground bonded with the >> negative input terminals, I discovered this >> because I am running a telecom rectifier shelf designed for -48 on a +48 >> system because it's floating, but this >> causes the + output to not be fused, so I practiced arc welding once. >> >> Strange, didn't know the 1100 had dc input, but it looks floating though >> (per specs -48, 12-57 V) >> >> >> >> >> On Sat, Sep 19, 2020 at 12:40 PM <ch...@wbmfg.com> wrote: >> >> I don’t think I have ever seen a true +48 load. >> >> >> >> *From:* Ken Hohhof >> >> *Sent:* Saturday, September 19, 2020 1:29 PM >> >> *To:* 'AnimalFarm Microwave Users Group' >> >> *Subject:* Re: [AFMUG] -48 noob questions (mikrotik) >> >> >> >> Different situation, but I have several sites with 1100ahx4 powered with >> +48, even though Mikrotik says they take -48. I suspect you will find the >> same to be true on the CCR. >> >> >> >> Connect the – terminal to ground and the + terminal to +48, obviously you >> don’t want to apply reverse polarity by trying to connect +48 to the -48 >> terminal. >> >> >> >> I have some ccr1009 and ccr1036 but they are all AC powered, and I have >> no ccr1072, so I can’t answer your exact question. >> >> >> >> >> >> *From:* AF <af-boun...@af.afmug.com> *On Behalf Of *TJ Trout >> *Sent:* Saturday, September 19, 2020 2:19 PM >> *To:* AnimalFarm Microwave Users Group <af@af.afmug.com> >> *Subject:* [AFMUG] -48 noob questions (mikrotik) >> >> >> >> So I have a handful of ccr1072's that I want to run on our +48v plant, >> mikrotik sells a '-48v telecom' power supply and they insist it's not >> compatible with +48v. I ordered one for testing and both +/- input >> terminals have no reference to chassis ground. I went ahead and applied >> +48v and the power supply fired up (no smoke) and when measuring from >> chassis ground to the input terminals I see no difference in potential. >> >> >> >> Before I shove this into a $3,000 router I wanted to see what I may be >> missing here? >> ------------------------------ >> >> -- >> AF mailing list >> AF@af.afmug.com >> http://af.afmug.com/mailman/listinfo/af_af.afmug.com >> >> -- >> AF mailing list >> AF@af.afmug.com >> http://af.afmug.com/mailman/listinfo/af_af.afmug.com >> >> ------------------------------ >> >> -- >> AF mailing list >> AF@af.afmug.com >> http://af.afmug.com/mailman/listinfo/af_af.afmug.com >> >> -- >> AF mailing list >> AF@af.afmug.com >> http://af.afmug.com/mailman/listinfo/af_af.afmug.com >> >> -- >> AF mailing list >> AF@af.afmug.com >> http://af.afmug.com/mailman/listinfo/af_af.afmug.com >> >> -- >> AF mailing list >> AF@af.afmug.com >> http://af.afmug.com/mailman/listinfo/af_af.afmug.com >> >> -- >> AF mailing list >> AF@af.afmug.com >> http://af.afmug.com/mailman/listinfo/af_af.afmug.com >> > -- > AF mailing list > AF@af.afmug.com > http://af.afmug.com/mailman/listinfo/af_af.afmug.com >
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