CB Radio re SWR question...ANSWERED (update)

hershey wrote:

Ah. Got it. So it is transmitting. A significant point - SWR has almost nothing to do with transmit or receive range. The reason we care about SWR is to keep the radio happy. So if you are perusing range, SWR is the wrong rabbit to chance. The efficiency of the antenna is where to look.

So, with a good SWR, you won't damage the radio. But to get good range, the cable and antenna need to be doing a good job of getting the signal in the wire into the air. The best way to test this is by measuring field strength - which can be coarsely done with just another receiver - like your handheld radio.

So using your theory, we can just stick a coat hanger in the back of the cb radio and we're as good as we can get when it comes to transmissions???? Maybe move it to the roof for a better view?
I'm being sarcastic I know but, I don't think your theory is accurate.

The principle is accurate. There are thousands of radios and antennas in use right now that are demonstrating this principle. A longer antenna is better than a shorter one, but let's stick to your coathanger idea.

If you were to just stick a coathanger wire out the back (but make sure we have a connection to ground too), the SWR would likely be very high and the radio would be "unhappy". Since we are stuck with the coathanger, let's add an antenna tuner. This is a inductor and/or capacitor network that changes the impedance that the radio sees and thus can keep the radio "happy". So now our SWR is 1:1, the radio is happy, and the antenna is no better or worse that it was before. Changing the SWR had no effect on the energy leaving the antenna.

The conclusion - get a better antenna or better location if you want better signal strength. SWR is the wrong rabbit to chase.

SWR of 1:1 on mid band is the MAX that can be achived
larger numbers are bad

SWR is term it means Standing Wave Ratio

or 'reflected power', power reflected back to the transmitter, power NOT going out

the 'capactance' and 'reactance' of the antenna circuit determines SWR

adjusting aka tuning the antenna circuit is done to minimize this reflection
and get max efficiency aka watts out the antenna and hence transmit range

all of this is affected by terrain

the best place to 'tune' the antenna is the middle of an open field
not always easy to find, a large empty stadium parking lot can be a good place

Ah. Got it. So it is transmitting. A significant point - SWR has almost nothing to do with transmit or receive range. The reason we care about SWR is to keep the radio happy. So if you are perusing range, SWR is the wrong rabbit to chance. The efficiency of the antenna is where to look.

So, with a good SWR, you won't damage the radio. But to get good range, the cable and antenna need to be doing a good job of getting the signal in the wire into the air. The best way to test this is by measuring field strength - which can be coarsely done with just another receiver - like your handheld radio.

So using your theory, we can just stick a coat hanger in the back of the cb radio and we're as good as we can get when it comes to transmissions???? Maybe move it to the roof for a better view?
I'm being sarcastic I know but, I don't think your theory is accurate.

OK, I'm back.

At one point I was ready to purchase a Firestick antenna, fiberglass roof mount model. It comes with a dedicated/mandatory 17 ft cable (do NOT modify). I gave up on this idea after I found out where and how Newmar ran the original coax cable (it was trapped, does not budge, can't access it).
Went back and reviewed everything I had read and learned (kinda) from y'all and from all the googling, plus from the Cobra manual.
I ran into an explanation about why there's no need to tune the antenna further, after you achieve 1.5 SWR on channels 1 and 40. It sounded good, so I went back and reviewed Squelch, DynaMike, RF Gain, etc. After playing with the radio adjustments, I started hearing truckers talking on channel 19 (they were on I-10, which is 4 miles away). THAT was good enough for me, so I quit.
I now believe my problem was my own ignorance regarding which way to knobble the knobs. I don't think there was anything wrong with the antenna.
Just another case of "the school of hard knocks".
I thank you again for your patience, and for all your help.

RoyB wrote:
---snip---
Always another project to get things like you want them. I used to get to listen to all of the local POLICE/RESCUE SQUAD frequencies but most of them in VIRGINIA now has gone to the digital mode... All I hear now is a loud BRRRRR when they transmit... geesch... Those scanners cost $400-$500 so I guess I won't be doing that anymore...

Roy Ken

If you ever do decide to dive in and buy an APCO25 scanner, make sure that the comms you want to listen to are not encrypted. If that's the case you'll be right back where you started and -$500 poorer..

I apologize!
I composed a long explaination, and got in a big hurry checking spelling and screwed up and deleted my draft. I'll try later 'cause right now I gotta go do something else. Sorry

I run the ICOM 706MKII with a TARHEEL HF screwdriver LIL-TARHEEL and two Comet SBB-7 top rear door mount 2M/440 on each side of the F150 truck for the ICOM VHF/UHF portion and another Kenwood 2m/440 rig in my console. I use two of those Kenwood KES-5 mobile speakers mounted in my drivers door side pocket. All sounds great right next to my knees... My LIL TARHEEL screwdriver didn't work all that well mounted to the top of the bed rail up close to the rear window. I added a pretty good flat braided ground strap to it its connector and grounded down at the frame which helped alot.

My remote ICOM head and the other 2m/440 remote head are mounted at a angle in on of the BLACK DESIGNER SPECIALTY three gang switch plates (LOWES). Got it velcroed at an angle down where the bottom of the upright truck console meets the console between the two captain seats in the truck. Perfect spot for my radio control heads.. My two remote microphones are hanging on the console between the two captain seats next to my right leg... Must be a good install as no complaints for mommabear yet. Also no holes in the roof on this install hehe...

I am tore plum up however from radio RFI coming from the trucks electronics on some of my favorite bands... Never have attemped to solve that noise yet... The FUEL TANK sender will be the first RFI mod I will do...

I have a nice small console mounted FWD/REVERSE RF power meter for the ICOM and my screwdriver tunes up great on the HF bands from indoor remote tuning switch...

Always another project to get things like you want them. I used to get to listen to all of the local POLICE/RESCUE SQUAD frequencies but most of them in VIRGINIA now has gone to the digital mode... All I hear now is a loud BRRRRR when they transmit... geesch... Those scanners cost $400-$500 so I guess I won't be doing that anymore...

Roy Ken

By the way.... Not a CB but a ham rig (kenwood TS-2000) I occasionally have transmit issues due to a broken wire on the mic plug.

I just replaced the entiere plug with a much improved model.. (NOTE this plug likely won't fit your CB, I mean it's 8 pin, most CB use 4 pin but broken wires happen on 4 pin as well).

Then I went to work on the dash radio in the RV.. I'm 99% sure I got it's problem too.. Will know for sure in a couple of months after running over many bumps and rail road tracks and the like.

Just keep in mind what you are working with..

With the 11-meter band it really doesn't matter much what you do to your antennas for tweaking this and tweaking that as you will still only be able to get two or three miles down the road. It is just the nature of the frequency being used.. When the skip is in on those frequencies then the 3-4 WATTS RF output may reach around the world but won't go more than two to three miles down the road.

Have dual antennas on the RV motorhome side mirrors works great like the truckers do. Finding a good groundplane spot on the roof is almost impossible. Their is no metal on most of the RV roofs...

Since the CELLPHONE ERA has come out now full force most all communications now between family members is using cellphone or amateur radio going through the repeater systems...

Just my take on the subject...
Roy Ken

I'm encountering obstacles such as this one:

This is a quote from the Firestik.com website.

"TESTING CONTINUITY

Checking your CB antenna system for continuity, shorts and opens is a MUST process and should always precede SWR checks and settings. Exception: Cable supplied with 'No Ground Plane' antenna kits will have continuity between the center lead and ground."

Surely they're not saying that the signal wire in the center is grounded? What am I missing?
On mine, the center wire in the coax ONLY has continuity to itself.