best antenna

[abcd567]

I believe it's RG174. Also the outer shield is dipped in solder to make it ridged solid.

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.

[F-EGLF1]

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.

[abcd567]

.....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

[abcd567]

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!

[1090 MHz]

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

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.

[1090 MHz]

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

[abcd567]

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".

[1090 MHz]

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.

[1090 MHz]

Something like this would be nice!

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

[charan]

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

[abcd567]

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

[charan]

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

[F-EGLF1]

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.

[F-EGLF1]

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.

[Birdie]

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.