Hello peeps ive recently installed a President Teddy CB with twin Astatic ALL3KB twigs which are mounted on mirror arms.The problems im having with it is im not picking anyone up only now and again.I was running with one of our drivers he was behind me ,i was picking him up but it wasnt a good signal.He suggested changing channel because someone else was on the same channel and was blowing his windows out but all i was getting was crackling.The twigs i got are supposed to be already SWRd so i dunno what the problem is.Anyone got any ideas 
SWR them anyway would be my advice…
You are better off with a stinger single twig.
Cheers Dave.
The Sarge:
SWR them anyway would be my advice…
^+1. Or swap rigs with your mate if you happen to be on a break together.
BIGRIG:
Hello peeps ive recently installed a President Teddy CB with twin Astatic ALL3KB twigs which are mounted on mirror arms.The problems im having with it is im not picking anyone up only now and again.I was running with one of our drivers he was behind me ,i was picking him up but it wasnt a good signal.He suggested changing channel because someone else was on the same channel and was blowing his windows out but all i was getting was crackling.The twigs i got are supposed to be already SWRd so i dunno what the problem is.Anyone got any ideas
You won’t. Mirror arms are the worst place to mount them. You have no ground worth speaking of and the maximum current of the antenna is inches away from the vertical metal of the cab. With mobile antennas, the most important thing is how much metal is directly under the antenna. RF ground is not the same as DC ground, meaning that just because its electrically connected it doesn’t mean you’ve a good RF ground. The best place to mount a mobile antenna is smack in the middle of the roof.
If you’re trying to co-phase antennas - i.e use two connected at the same time, its a bit more complicated than just getting two antennas, connecting them to a T connector and from the T connector to the radio. The co-ax needs to be very specific lengths. They’ll also need retuning as co-phasing throws pre-tuned SWR out of the window. Also it’ll alter the radiation and reception pattern so you’ll get far less transmit and received signal forwards and backwards but you’ll get increased signal to the sides.
When you fit twin twiggs you use 75 ohm co-ax rather than the standard 50 ohm type wich is more common and used with single antenna set up’s, check for this, the type will be printed on the side of the cable insulation
if the cable is wrong you will never get it to work right!
to swr twins is more hasstle than a single twig as a rule and to get the best results they need to be 8ft+ gap between twiggs and of a centre load type (the coil in the centre of the twigg rather than a base load type such as a stinger or modulator)
base loaded twiggs dont tend to work well as a twin set up!
moose
SWR is a no brainer, but you need decent Co-Ax and a good earth to get a decent signal/reception. With a twin aerial set up the Co-Ax must also be an equal length to both aerials, you’ll also want to keep any wiring away from any other powered wiring 
Thanks for your help peeps. 
Save yourself a lot of grief and just stick to one antenna. By all means leave two mounted if you like the symmetry of it but use a single length of quality 50 ohm coax to just one of them.
newmercman:
SWR is a no brainer, but you need decent Co-Ax and a good earth to get a decent signal/reception. With a twin aerial set up the Co-Ax must also be an equal length to both aerials, you’ll also want to keep any wiring away from any other powered wiring
As far as I know the CB radio wave length is about 11 meters
so if you have 2 dipole aerials they will need to be 11 meters apart
How many miles can you talk to your other driver before you loose him?
Boss & Driver:
newmercman:
SWR is a no brainer, but you need decent Co-Ax and a good earth to get a decent signal/reception. With a twin aerial set up the Co-Ax must also be an equal length to both aerials, you’ll also want to keep any wiring away from any other powered wiringAs far as I know the CB radio wave length is about 11 meters
so if you have 2 dipole aerials they will need to be 11 meters apartHow many miles can you talk to your other driver before you loose him?
Not that far really.If i disconnect one twig would it work or will i have to get new coax
We’re grateful to get out 1 mile with our cbs…
One thing I have not seen in this thread is the noggin of 75 Ohm coax.
Now the boring bit
Each aerial is 50 Ohms (ish) impedance
50 + 50 = 100 Ohms or 2:1 SWR
1.8 metres of RG59 (75 Ohm) will transform the feeder back to 50 Ohm (1:1 SWR near enough)
As was said the coax from the aerials to the “Tee” has to be equal lengths then the 75 Ohm coax then 50 Ohm to the radio.
Check the SWR you may have a bad connection
G8YMW:
As was said the coax from the aerials to the “Tee” has to be equal lengths then the 75 Ohm coax then 50 Ohm to the radio.
Check the SWR you may have a bad connection
Both coax’s act as an antenor them selfs
So they need to be equal to match the radio wave
other wise you may as well have a 10 foot antenna and a 10 inch antenna
But hight quality coax with low resistance and good connection is the way to go
Muckaway:
We’re grateful to get out 1 mile with our cbs…
Grateful should not be the word
Boss & Driver:
Muckaway:
We’re grateful to get out 1 mile with our cbs…
Grateful should not be the word
I know mate, cheap glass fibre antennae and I bet the coax is wrapped up in the headlining 
Mine’s not bad, but I think many drivers have their squelch whacked up high.
Boss & Driver:
G8YMW:
As was said the coax from the aerials to the “Tee” has to be equal lengths then the 75 Ohm coax then 50 Ohm to the radio.
Check the SWR you may have a bad connectionBoth coax’s act as an antenor them selfs
No they don’t. They do if you’ve not installed the antenna properly.
So they need to be equal to match the radio wave
other wise you may as well have a 10 foot antenna and a 10 inch antenna
My antenna is 75ft long. I have no idea how long the co-ax is as I just used the shortest length needed to get from the radio to the antenna.
The antenna is used on 1.8Mhz, 3.5MHz, 5MHz, 7MHz, 10MHz, 14MHz, 18MHz, 21MHz, 24MHz and 28MHz. What is the correct length of co-ax I’m supposed to be using?
But hight quality coax with low resistance and good connection is the way to go
Wrong. High quality co-ax with the correct impedance is the way to go.
Boss & Driver:
newmercman:
As far as I know the CB radio wave length is about 11 meters
so if you have 2 dipole aerials they will need to be 11 meters apart
Rubbish.
Muckaway:
We’re grateful to get out 1 mile with our cbs…
Looking at this thread it comes as no surprise. A friend and I typically work 20+ miles on CB. Thats mobile to mobile with 4W at each end. He has an old Maxon thing and has a Sirio 4000 mounted on a mount drilled into the roof of his van and I have a Maycom EM-27 running into a Sirio 3000 mounted on a mount drilled into the roof of my car.
I should set up a business installing CBs in trucks.
Conor:
Muckaway:
We’re grateful to get out 1 mile with our cbs…Looking at this thread it comes as no surprise. A friend and I typically work 20+ miles on CB. Thats mobile to mobile with 4W at each end. He has an old Maxon thing and has a Sirio 4000 mounted on a mount drilled into the roof of his van and I have a Maycom EM-27 running into a Sirio 3000 mounted on a mount drilled into the roof of my car.
I should set up a business installing CBs in trucks.
The bloody things are too complicated i think two tin cans and a long piece of string would be better