Setting SWR on cb radio

So I just installed a new honda cb radio with antenna on my 2012 wing. I was setting the SWR and need a questioned answered. So on ch. 1 I am getting a 2.8 and ch 40 a 1.6,,,, I raised my antenna as much as I could to keep the set screw still on it. My readings are now ch. 1 is 2.5 and ch. 40 is 1.3. Thats all the adjustment in raising the antenna,,,so is this ok??? thanks rj

redjetty said:

So I just installed a new honda cb radio with antenna on my 2012 wing. I was setting the SWR and need a questioned answered. So on ch. 1 I am getting a 2.8 and ch 40 a 1.6,,,, I raised my antenna as much as I could to keep the set screw still on it. My readings are now ch. 1 is 2.5 and ch. 40 is 1.3. Thats all the adjustment in raising the antenna,,,so is this ok??? thanks rj

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It's been a while since I set my SWR so I don't recall what the final outcome was. I moved it up 1/16th of an inch at a time until I was pleased. I do remember setting SWR is really tricky. Your body makes some pretty significant changers in transmission pattern. To be honest. I think it is a waste of time. The GL1800 C/B is and always has been adequate at best. Works OK for communicating in small groups (maybe a mile or so) but otherwise pretty much useless. :xszpv: :xszpv:

In all the years I have installed and tuned the SWR on a multitude of radio and antenna brands + tuned SWR on numerous Gold Wings and Harleys, I have never once had to raise the antenna! I have always had to grind off the end of the antenna to achieve the lowest SWR possible.

Also, I tuned on the channel I would use the most and accepted what the rest turned out to be.

The 2.8 you got on channel 1 is way to high, IMHO

I would suggest you lower the mast again til it bottoms out. Then start grinding about 1/8" at a time off of it, checking the SWR each time.

Make sure the bike is outdoors and not near any buildings, trees or power lines. Each time you check the SWR, knell down beside the bike to remove your bodies influence on the reading.

Properly done, this is a slow process but a very good SWR can be accomplished.

I use channel 2 mostly and my SWR is 1.3 on that channel. On most days I can transmit 3 to 5 miles, depending if it is to a cage, truck or another bike. You will always receive from a much greater distance than you can transmit on a bike. Also, atmospheric conditions have a lot to do with how much static you receive. The more the sun spots are active the higher you have to set you squelch.

Now that you mention it, I did have to shorten my '01 antenna stinger. The '06 and '15 were both fairly good so I didn't make any alterations. :xszpv::xszpv:

There is a lot of unnecessary anxiety over SWR.

You must remember what SWR is and what causes it. It is simply the ratio of the load impedance/source if the load impedance is higher than the source impedance. If the load impedance is lower than the source impedance, it flips to source/load. (SWR can’t be less than 1.0) A CB radio has a source impedance of 50 ohms. When the impedance of your antenna is exactly 50 ohms, your SWR is 1.0.

What if your SWR meter shows 2.0? It means that the antenna impedance is either 100 (100/50=2) ohms or 25 (50/25=2) ohms. You can’t tell which unless you have an expensive antenna analyzer. But it really doesn’t matter.

Your owner’s manual will tell you the maximum SWR to use for your radio. For most it will be 2.0

If you can get your antenna set so that the SWR on every channel is 2.0 or less, you are good to go.

It’s great if you can get the SWR on your favorite channel to 1.5. Trying to tune for less than that is a waste of time.

As a tuning tip:

If the SWR on channel 40 is higher than that on channel 1, your antenna is too long.

If the SWR on channel 1 is higher than that on channel 40, your antenna is too short.

PS: Some folks use terminology like 1:1, 2:1, and 1.5:1. That’s the same as 1.0, 2.0 and 1.5.

And if I remember correctly, pretty big reason the motorcycles don't transmit very well is the lack of a flat metal base under the antenna (pretty sure I read that somewhere).

If the SWR on channel 1 is higher than that on channel 40, your antenna is too short.

PS: Some folks use terminology like 1:1, 2:1, and 1.5:1. That’s the same as 1.0, 2.0 and 1.5.[/QUOTE]

So,,, what do I do if I am raising my antenna and have no more length to raise up? ,,

FuzzyWuzHe said:

And if I remember correctly, pretty big reason the motorcycles don't transmit very well is the lack of a flat metal base under the antenna (pretty sure I read that somewhere).

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That is correct.

The "whip" antenna usually used on motor vehicles is really only half of an antenna and the metal below it (ground plane) acts kind of like a mirror to provide the other half.

Mounting the antenna on a significant metal surface goes a long way. Mounting on a metal luggage rack usually gives good results.

redjetty said:

If the SWR on channel 1 is higher than that on channel 40, your antenna is too short.

PS: Some folks use terminology like 1:1, 2:1, and 1.5:1. That’s the same as 1.0, 2.0 and 1.5

So,,, what do I do if I am raising my antenna and have no more length to raise up? ,,

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Well, if I was in your position I would just let it go at that. It is the best you can do with the antenna you have.

Your OP says you have SWR of 2.5 on channel 1 and 1.3 on channel 40.

That is not so bad.

Very true about the lack of ground plane(metal body) on a motorcycle. That's why, at best, 3 to 5 miles transmit range with a properly, carefully tuned SWR,

Explanation of to long to short on channel 1 vs. channel 40, not so much for me! Might be true but, as I posted earlier, I have been a CB'r since the early 60's. In all those years I have never found a new antenna to short to begin with!

I also stand by the fact any SWR that is above 2 can be vastly improved.

One thing many people overlook is the wattage on a CB radio. I have had several that were lower than the legal limit! Getting hard to find CB shops to tune the radio up anymore. Still several truck stops have CB shops,

I've owned 9 Goldwings, all with CB's and never had to mess with setting anything. Last time I set the SWR on a CB was 1975 when we installed one in my buddy's Ford van.