Announcement

Collapse
No announcement yet.

best antenna

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • Originally posted by 1090 MHz View Post
    I believe it's RG174. Also the outer shield is dipped in solder to make it ridged solid.
    Originally posted by charan View Post
    Yes it was shorted at the top
    and i'm thinking to order RG402 cable. will there be any improvement with coco antenna or is the same? and also i don't know the VF of my current coaxial and i jus used 11cm.. and i dont have the cable now to make it so i have to buy it. so which would be the better ? RG402 or RG6?
    RG402 & RG174 both have 50 ohm impedance. FR24 receiver, I believe, but not sure, is also 50 ohms. A perfect match. The DVB-T USB Dongle's input impedance is 75 ohms. Although there will be a mismatch 50 ohms to 75 ohms, the SWR will be only 1.5, a respecable and aceptable figure.
    Last edited by abcd567; 2014-04-28, 21:22.

    Comment


    • Originally posted by 1090 MHz View Post
      I believe it's RG174. Also the outer shield is dipped in solder to make it ridged solid.
      It is definitely RG402, mine arrived today and I have begun to build my 1st coco, it should go on the analyser tomorrow lunchtime, but final results will have to wait till next week as I need to get the plastic pipe that it will go in before I can do the final tuning.
      If all goes well then I will build a second one with step by step photos and accurate (to 0.01mm) measurements for others to try.
      Ben.

      NB yes the FR24 receiver is 50-ohms, also the analyser is set up for 50-ohms.

      Also you would have problems trying to use RG174 as it is polyethylene cored and would melt at soldering temperatures, RG402 is PTFE cored which makes assembly a real joy as it does not melt or sag.
      Last edited by F-EGLF1; 2014-04-28, 21:40. Reason: Cable core info
      FR24 F-EGLF1, Blitzortung station 878, OGN Aldersht2, PilotAware PWAldersht, PlanePlotter M7.

      Comment


      • Originally posted by F-EGLF1 View Post
        .....NB yes the FR24 receiver is 50-ohms, also the analyser is set up for 50-ohms.
        With 50 Ohm connected to 75 Ohm:

        Reflection Coefficient Γ = (Z1 - Z2) / (Z1 + Z2) = (75-50)/(75+50) = 0.2
        VSWR = (1+Γ)/(1-Γ) = (1+0.2)/(1-0.2) = 1.5 : 1

        Don't get terrified by 1.5:1 VSWR ...
        The Mismatch Loss in dB = -10 log(1 - Γ2) = -10 log (1-0.2 2) = -10 x -0.01773 = 0.1773 dB .... peanuts

        Comment


        • A very easy formula to calculate SWR when soure and load impedances Z1 & Z2 are known:

          SWR = Z1/Z2 where Z1 is larger of two impedances.

          Example 1:
          Antenna (source) 50 ohms, receiver (load) 75 ohms SWR = 75/50 = 1.5

          Example 2:
          Folded dipole Antenna (source) 300 ohms, receiver (load) 75 ohms, SWR = 300/75 = 4

          Simple & easy maths!
          Last edited by abcd567; 2014-04-28, 23:00.

          Comment


          • Yes looking at the RG402 specs it definitely is it... but it does look like some 174 that's been tinned.

            Originally posted by F-EGLF1 View Post
            It is definitely RG402, mine arrived today and I have begun to build my 1st coco, it should go on the analyser tomorrow lunchtime, but final results will have to wait till next week as I need to get the plastic pipe that it will go in before I can do the final tuning.
            If all goes well then I will build a second one with step by step photos and accurate (to 0.01mm) measurements for others to try.
            Ben.

            NB yes the FR24 receiver is 50-ohms, also the analyser is set up for 50-ohms.

            Also you would have problems trying to use RG174 as it is polyethylene cored and would melt at soldering temperatures, RG402 is PTFE cored which makes assembly a real joy as it does not melt or sag.
            www.ADS-B.ca

            Comment


            • Here's a tip when using PVC pipe. Place a piece in a Microwave and give it 60 seconds. If the pipe gets hot, then there is lead or some other type of metal in it and it's NOT suitable for use as a radome
              www.ADS-B.ca

              Comment


              • Originally posted by 1090 MHz View Post
                Here's a tip when using PVC pipe. Place a piece in a Microwave and give it 60 seconds. If the pipe gets hot, then there is lead or some other type of metal in it and it's NOT suitable for use as a radome
                Brilliant idea. A very handy way to test. Thanks "1090 MHz".

                Comment


                • http://chej.org/2013/09/pvc-pipes-br...rinking-water/

                  Lead is used in:

                  95 percent of PVC pipe in India
                  91 percent in China
                  86 percent in the Middle East and Africa
                  61 percent in South America
                  29 percent in Europe
                  1 percent in North America which uses tin as a stabilizer.

                  So North America PVC is safer for drinking water, but it still had Tin in it...

                  I think this is why professional manufactured antennas use Fiberglass for the radome.
                  www.ADS-B.ca

                  Comment


                  • Something like this would be nice!

                    http://www.ebay.com/itm/Fiberglass-R...-/151287851164
                    www.ADS-B.ca

                    Comment


                    • Originally posted by 1090 MHz View Post
                      http://chej.org/2013/09/pvc-pipes-br...rinking-water/

                      Lead is used in:

                      95 percent of PVC pipe in India
                      91 percent in China
                      86 percent in the Middle East and Africa
                      61 percent in South America
                      29 percent in Europe
                      1 percent in North America which uses tin as a stabilizer.

                      So North America PVC is safer for drinking water, but it still had Tin in it...

                      I think this is why professional manufactured antennas use Fiberglass for the radome.
                      OMG now i should stop drinking water
                      RTL SDR : T-VEVZ1

                      Comment


                      • Originally posted by charan View Post
                        OMG now i should stop drinking water
                        We are lucky. Some time ago when upgrading work was done in our kitchen, I asked the supervisor "why dont you use pvc pipe instead of copper pipe? It is cheaper", he said "Ontario building regulations do not allow pvc pipes for water in residences"

                        Sent from my N762 using Tapatalk 2

                        Comment


                        • Originally posted by abcd567 View Post
                          We are lucky. Some time ago when upgrading work was done in our kitchen, I asked the supervisor "why dont you use pvc pipe instead of copper pipe? It is cheaper", he said "Ontario building regulations do not allow pvc pipes for water in residences"

                          Sent from my N762 using Tapatalk 2
                          Yeah seriously ! and i should say that your regulations are AWESOME. here in India there is lot of corruption. they dont maintain standards..
                          The problems facing by us now are :-
                          Powercuts - 4 and half hour a day, i'm living in city
                          the contractors and also some fellow members take bribe and maintain worst standards in roads, etc
                          vegetables rates are going high,
                          we have to sell our vehicles to buy petrol,
                          no stability in government, they fight each other instead of working together,
                          and many more i cant explain here all but in this stupid state .. they divided our state into two making situation even worse.
                          i'm like waiting to go out of india and get job somewhere else in the world where the humanity is still alive i dont want much money but just to be safe and peaceful. which is not possible in INDIA
                          RTL SDR : T-VEVZ1

                          Comment


                          • Originally posted by 1090 MHz View Post
                            http://chej.org/2013/09/pvc-pipes-br...rinking-water/

                            Lead is used in:

                            95 percent of PVC pipe in India
                            91 percent in China
                            86 percent in the Middle East and Africa
                            61 percent in South America
                            29 percent in Europe
                            1 percent in North America which uses tin as a stabilizer.

                            So North America PVC is safer for drinking water, but it still had Tin in it...

                            I think this is why professional manufactured antennas use Fiberglass for the radome.
                            Here in the UK there are different grades for drinking water, waste water and central heating, you can only use approved pipe for 'potable' water and it is marked as such, some I have seen have a 2 part construction with a white liner and a stiffer outer.
                            However the drinking water grade would not be suitable for antennae work as it is quite soft and usually blue in colour.
                            Ben.

                            NB we also banned the use of lead solder for copper pipes many years back.

                            CORRECTION, in the UK we don't use PVC for water (other than waste), the water pipes are PU (Polyethylene) with or without a liner.
                            Last edited by F-EGLF1; 2014-04-29, 05:54. Reason: Correction
                            FR24 F-EGLF1, Blitzortung station 878, OGN Aldersht2, PilotAware PWAldersht, PlanePlotter M7.

                            Comment


                            • Originally posted by 1090 MHz View Post
                              Here's a tip when using PVC pipe. Place a piece in a Microwave and give it 60 seconds. If the pipe gets hot, then there is lead or some other type of metal in it and it's NOT suitable for use as a radome
                              Fantastic idea, however a word of caution..
                              Microwave ovens dislike being run empty, that energy has to go somewhere and if it reflects back into the magnetron it can damage it, it is always good practice to put a cup of water in the oven when you do something like this just as a 'dummy load' I will be testing the pipe I am getting for my first coco build this way before I use it (or discard it)
                              Ben.
                              FR24 F-EGLF1, Blitzortung station 878, OGN Aldersht2, PilotAware PWAldersht, PlanePlotter M7.

                              Comment


                              • Originally posted by abcd567 View Post
                                We are lucky. Some time ago when upgrading work was done in our kitchen, I asked the supervisor "why dont you use pvc pipe instead of copper pipe? It is cheaper", he said "Ontario building regulations do not allow pvc pipes for water in residences"

                                Sent from my N762 using Tapatalk 2
                                In Singapore, only copper or stainless steel pipes are used for drinking water.

                                For copper pipes, NO soldering of joints but only use couplings to joing th epipes.
                                F-WSSS1 - Cats refused to Pee & Pooh on RadarBox - Running a FR24 Receiver & DVB-T Dongle 24/7 to piss off The Chief Thief.

                                Comment

                                Working...
                                X