how to swr a cb

[pirate-storm]

The SWR meter needs to be placed in line between the antenna and the CB. Connect the antenna (normally connected to the back of the CB ) to the connector marked "Antenna" or "Ant" on your SWR Meter. Connect one end of the short jumper coax to the "transmit" or "Xmit" on the SWR meter. Connect the other end of your jumper coax to the CB.

Assuming you have a standard SWR meter the switches should read as follows: REF or SWR, FWD, and there should be a slide switch marked "set" or "Adjust". If different consult your meter's owners manual.

With the radio on the lowest channel (1 on CB) and the SWR meters switch in the Forward (FWD) position, depress the transmit switch (key up) located on the microphone. While holding the unit in this transmit mode, adjust the meter needle to the set position using the Set or Adjust knob on the meter. As soon as the needle is in alignment with the corresponding mark on the meter face, flip the switch to the Reference (REF) position. The meter is now showing your SWR on channel one. Note the value and quickly release the microphone switch. Record this reading.

Repeat the previous step on channels 19 and 40.

How to read your results: If SWR on channels 1, 19 & 40 is below 2.0, your radio can be operated safely.

If SWR on all channels is above 2.0 but not in the "red zone" (normally over 3.0), you may be experiencing coaxial cable reaction (bad quality, wrong length, etc.), insufficient ground plane, or have an ungrounded antenna mount.

If SWR is in the "red zone" on all channels, you probably have an electrical short in your coax connectors, or your mounting stud was installed incorrectly and is shorted. Do not operate your radio Do not operate your radio until

If SWR on the lowest channel is higher than it is on the highest channel, your antenna system appears to be electrically short. Your antenna length may need to be increased.

If the SWR on channel 40 is greater than that on channel 1, your antenna is considered to be "LONG" and reduction of physical height and/or conductor length will correct this situation.

[BUSHWHACKER]

Also, I've heard it's advisable to try and keep the co-ax cable as straight as possible, with no sharp bends or kinks, is this correct?

[pirate-storm]

Also, I've heard it's advisable to try and keep the co-ax cable as straight as possible, with no sharp bends or kinks, is this correct?

your going to get some bends anyway m8 but you def dont want any kinks

[plumb bob]

Yup, did that, SWR is slightly higher on ch40, but both still in the red.

I guess I'll have to uninstall the rig tomorrow, and check the connections at the rear of the unit, and make sure my patch lead is ok, and then maybe phone the guy I bought it from on monday.

Trouble nowerdays is you can't get any bits and bobs locally, it,s all via 'tinernet.

[pirate-storm]

Yup, did that, SWR is slightly higher on ch40, but both still in the red.

I guess I'll have to uninstall the rig tomorrow, and check the connections at the rear of the unit, and make sure my patch lead is ok, and then maybe phone the guy I bought it from on monday.

Trouble nowerdays is you can't get any bits and bobs locally, it,s all via 'tinernet.

yeah i was going to say aswell check the connections in the pl259 on both ariel lead n patch lead

[gwh200]

its best to keep any current carrying vessel straight,as there is a magnetic field generated ,which is perpendicular to the electrical flow.

if you introduce an em influence several times at several different planes,
by the B.ds integral you will introduce interference,when generating a seperate sinusoidal wave,

yes im sure ive read somewhere vince the same thing though

[plumb bob]

its best to keep any current carrying vessel straight

Aye, or you'll spill 'em

[mark g8awo]

Its simple i got a box of tricks that tells me the resonant frequency of the antenna without all this faffing around with Voltage Standing Wave Ratio bridges so no swaring is needed....swaring is what you do when you clump your thumb with the hammer. I can measure all sorts of things with this clever box from capacitance to resitance and find out how far down the feeder a short is. So your 102 inch length of wire is nothing but chicken feed to what i deal with from something that can be a quater of a mile long to something thats millimeters. My best conquest was using a 150ft vertical 20 68ft radials for 3.5Mhz and working the whole country with 2watts

[plumb bob]

Just been reading the yotatech site, lots of stuff on cb's there.

There was one mention of a plastic washer between the antenna and the mount, to stop antenna grounding, I don't recall seeing/reading about this in any instructions, so should I have this absent washer??

[Apache]

its best to keep any current carrying vessel straight,as there is a magnetic field generated ,which is perpendicular to the electrical flow.

Oh here comes 'theory boy'.

No, in reality, the lines of force have no bearing on practicality. Keep bends in RF cables large as you dont wanna squash the dielectric in the cable as you'll change the capacitance and ergo the impedance, and end up with reflections, otherwise known as high SWR, and in the levels of RF power I'm dealing with in my current job, fires and exploding amplifiers!

[Apache]

Its simple i got a box of tricks that tells me the resonant frequency of the antenna without all this faffing around with Voltage Standing Wave Ratio bridges so no swaring is needed....swaring is what you do when you clump your thumb with the hammer. I can measure all sorts of things with this clever box from capacitance to resitance and find out how far down the feeder a short is. So your 102 inch length of wire is nothing but chicken feed to what i deal with from something that can be a quater of a mile long to something thats millimeters. My best conquest was using a 150ft vertical 20 68ft radials for 3.5Mhz and working the whole country with 2watts

There's nothing like properly matching your antenna eh Mark?

[plumb bob]

Ok, I changed the patch lead between the cb and the swr meter, no change.
The swr is 2.5 on ch1 and 3 on ch40, so the ariel is electrically long ( from what I've read.

If I switch to euro am channels, the swr is about 1.5 across the range, so the ariel seems better tuned to am.

Do you reckon I need to cut the whip to shorten it, I was trying to avoid cutting it if poss.

[mark g8awo]

Ok, I changed the patch lead between the cb and the swr meter, no change.
The swr is 2.5 on ch1 and 3 on ch40, so the ariel is electrically long ( from what I've read.

If I switch to euro am channels, the swr is about 1.5 across the range, so the ariel seems better tuned to am.

Do you reckon I need to cut the whip to shorten it, I was trying to avoid cutting it if poss.

Yes it is too long

An easy way to check things out before you cut it is use something like a welding rod and trim that to length first then you cut the original whip to length hey presto measured twice cut once theory cos you cant glue it back on afterwards

[plumb bob]

Yes it is too long

An easy way to check things out before you cut it is use something like a welding rod and trim that to length first then you cut the original whip to length hey presto measured twice cut once theory cos you cant glue it back on afterwards

Yes, I thought about that, but can't find anything 5' long.

[pirate-storm]

Yes, I thought about that, but can't find anything 5' long.

hmmmmmmm still sounds like a earth prob to me. also you could try moving the mag mount around abit n see if that helps as when i had the pre-swr ariel i had to move it around then the swr came down. also you could check the earth n live wire on the ariel pl259 also on the patch hold the back of patch lead n move slightly to see if that brings swr down as it could be a connection prob.
i would still expect the swr to be lower than 2.5 n 3 on top personally i cant see cutting it down abit will help if swr up that high but will admit i could be wrong but i would expect channel 1 to be down 1.1.5 - n high on 40 like you have to cut some down abit but mark being a ham will say anyway