swr meters frequency specific?

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kb1rbz
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Location: palmer,ma

swr meters frequency specific?

Post by kb1rbz » Tue Aug 26, 2008 9:02 pm

Wanted to clear up a question I have received different answers on. Will a swr meter from c.b. radio work on ham radio or are they designed for certain frequencies only? :?:

marty_wittrock
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Location: Iowa

About SWR Meters....

Post by marty_wittrock » Wed Aug 27, 2008 4:38 am

Most good SWR meters are based on a somewhat wideband directional coupler and diode detector to show forward and reverse power as DC current sent to the meter. If calibrated well, most CB SWR meters will work over a +/-10MHz range (17MHz to 37 MHz) with some error (about 10%) at each end, optimally working at 27 MHz, provided that the meter is of any good design integrity at all (read here: it's not a cheap $10.00 SWR meter). For 10m (28 MHz - 29 MHz) there will be no perceptible error and should be fairly accurate since there isn't a lot of difference (at that frequency range) that the directional coupler would be that far off the mark (less than 2 - 5% error in your measurement FWD/REV power). It's when you start for the 20m band (14.0 MHz) and below that the (as designed) directional coupler will be very inefficient and provide you with a lot of error since the that directional coupler in the meter is not well tuned (designed) for those lower frequencies and the manufacturer wouldn't spec the meter over that wide of a bandwidth. As well, you're fighting the age old CB=4W, versus Ham transceivers could be anything from 1W to 2000W. If the meter was designed for CB use, chances are it's probably useful to read full scale power up to 15W PEP and that's about it. Once you drive anything over that maximum power (15W PEP) input you'll 'fuse' open the directional coupler and render the meter inoperative. So you have to be mindful of that, too. The moral to this story is: If you want to use it on 10m and have a QRP rig to use it on, it's going to work great. Otherwise, contact CheapHam or some other Ham accessory store on the web and get yourself a real HF (2 - 30 MHz) Watt/SWR meter - - your call on how much you want to spend on that....HI HI.

73's de Marty, KN0CK
de Marty (KN0CK)

kb1rbz
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Location: palmer,ma

Post by kb1rbz » Sun Aug 31, 2008 1:08 am

thank you for clearing this up. :D

W4AIN
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Re: swr meters frequency specific?

Post by W4AIN » Tue Nov 04, 2008 1:28 am

kb1rbz wrote:Wanted to clear up a question I have received different answers on. Will a swr meter from c.b. radio work on ham radio or are they designed for certain frequencies only? :?:
I guess it depends on the meter...I contacted an engineer that works on the design team for the DOSY wattmeters (Test Centers) and he tells me that some of their meters (even though they are aimed at CB) have been proven to work accurately from 10m-80m.
Phil - W4AIN
On The Air Communications
www.w4ain.com

WA9WVX
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VSWR meters frequency specific?

Post by WA9WVX » Tue Nov 04, 2008 9:51 pm

Hello Phil - W4AIN.

Perhaps you should contact your buddy engineer at DOSY Products and find out what the Frequency Bandwidth actually is, "especially" the highest frequency that this DOSY meter is capable of measuring any VSWR? I couldn't find anything on DOSY website indicating the Cut-Off Frequency Response.

I know for a fact that KB1RBZ was trying to measure the VSWR on the 144~148 MHz 2 Meter Band. He ended up purchasing a MFJ VHF/UHF VSWR Bridge but he had the same High VSWR 3:1 readings.

You've got to ask yourself, "What are the Odds for a 3:1 mismatch to happen on two completely different VSWR Bridges? And where does the Root Cause problem really exist?"

Let me take this issue one step further, the antenna manufacture sent an identical replacement antenna out to KB1RBZ home and he connected the new antenna up to the same feedline LMR-400, the same IC-V8000 and the same MFJ VHF/UHF VSWR Meter and still hand the same VSWR 3:1 measurement.

Phil, Can you determine where the Root Cause problem originates?? I definitely know what and where KB1RBz antenna mismatch and/or High VSWR measurements exist and it's waving a Flag at everyone else except me.

73,

Dan
WA9WVX

W4AIN
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Location: Louisville, KY

Re: VSWR meters frequency specific?

Post by W4AIN » Wed Nov 05, 2008 12:53 am

WA9WVX wrote:Hello Phil - W4AIN.

I know for a fact that KB1RBZ was trying to measure the VSWR on the 144~148 MHz 2 Meter Band. He ended up purchasing a MFJ VHF/UHF VSWR Bridge but he had the same High VSWR 3:1 readings.
Dan, I was not aware that this was a VHF issue. As I stated, some of the Dosy meters will operate 10m-80m. The question for this topic was asking whether or not 'CB' meters would work with ham radio. The answer to that question is in my previous post. Now if the question had stated that the ham frequencies in question were VHF, then I would have addressed that issue.

he connected the new antenna up to the same feedline LMR-400, the same IC-V8000 and the same MFJ VHF/UHF VSWR Meter and still hand the same VSWR 3:1 measurement.
This was not addressed in the question.
Phil, Can you determine where the Root Cause problem originates?? I definitely know what and where KB1RBz antenna mismatch and/or High VSWR measurements exist and it's waving a Flag at everyone else except me.
The problem is obviously with the feedline. But this could not possibly be determined with the information that was presented here by KB1RBZ. Actually, he NEVER asked in this topic what the cause could be, but rather just wanted to know if 'CB' meters would work on Ham Radio frequencies.
Phil - W4AIN
On The Air Communications
www.w4ain.com

wx1f
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Re: swr meters frequency specific?

Post by wx1f » Wed Nov 05, 2008 9:32 am

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W4AIN
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Location: Louisville, KY

Re: swr meters frequency specific?

Post by W4AIN » Wed Nov 05, 2008 7:40 pm

Good grief....why can't people just answer a simple question in a simple manner!!!
In answer to your question in plain simple English: NO...your CB SWR Meter is for CB. If you need to check SWR on HF, VHF or UHF...buy a meter designed for that frequency.
Ok...How is this for simple, Gordon. YES it will work, depending on the meter you have.

I have the little SWR / Field Strength meters that were marketed for CB use. They were sold under different brand names such as GC Electronics, Regency, Midland, and others. They are designed to operate from 3MHz to 150MHz. I pick them up at hamfest for $5.00 or less.

There you go, a simple answer that is much more accurate than the presupposition that CB meters will not work for amateur radio.

Oh, BTW Rory...I'm not a rocket scientist...just a knowledgeable ham that will give you an honest answer and not hung-up on the 'ham is superior to CB' notion.

73
Phil - W4AIN
On The Air Communications
www.w4ain.com

wx1f
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Re: swr meters frequency specific?

Post by wx1f » Wed Nov 05, 2008 8:36 pm

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W4AIN
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Re: swr meters frequency specific?

Post by W4AIN » Wed Nov 05, 2008 9:05 pm

wx1f wrote:
Phil
I don't want Rory to fry his equipment by using the wrong meter....so...I'm saying NONE of your "dime a dozen" cb meters will have a 3-150Mhz freq printed on their written instructions.....nor will they have an rf output range over 15 watts !! If you can SHOW JUST ONE, WITH 150 WATT SPECS under any of the names you gave off the net.....I will bow to your superior hamness !
I have used the GC Electronics and Midland meters at power levels of 250w HF and 150w VHF with no problems. I am speaking of the older (20yrs+) SWR/FS meters...Not the modern POWER/SWR/FS meters. And yes, they are rated by the manufacturer as HF/VHF meters with ratings in excess of 150w!!
Gordon, this has nothing to do with who is superior. I am just trying to help a fellow ham save some bucks without sacrificing quality. Perhaps money is no object to you when purchasing equipment. If that is the case, then spend away. You don't have to put others down and be so rude just because in your puny little mind you think you are superior to the rest of us. -CLICK-
Phil - W4AIN
On The Air Communications
www.w4ain.com

wx1f
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Re: swr meters frequency specific?

Post by wx1f » Wed Nov 05, 2008 11:41 pm

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WA9WVX
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VSWR Bridges

Post by WA9WVX » Thu Nov 06, 2008 12:43 am

Okay Guys,

Here's one of my biggest problems with these newbies when they are asking for Help on these Forums. They start out asking a question about basic test equipment but don't provide the failure or problem. They receive one or more answers. Then they Open another Post that is directly tied to the original Post but everyone has to sit there and guess what the individual is actually having a problem with on his system configuration. I don't know about you guys but some where I msiplaced my crystal ball or my carnac attire and I've never been that good at reading a person's mind. What is wrong with being supplied the basic information on any Post? And many of these newbies won't supply adequate answers to your questions.

Here's Rory second Post for the same problem which is directly related to his VSWR problem:

http://chat.qth.com/viewtopic.php?t=5121

Phil W4AIN, you're on the right track regarding the Feedline but there's unlying issues that Gordy WX1F (being an Extra Class Licensee) should be able to provide a concelse technical answer for the 3:1 VSWR readings. As I've stated before, "I know what is exactly wrong with Rory's KB1RBZ configuration and test procedures."

Oh BTW, Gordy, the Antenna Designer and Manufactrure people both being Amateur Extra Class Operators contacted me via the PM route explaining their position on the first antenna and the replacement one. They were baffled on Rory's method of measuring the VSWR on his set-up. You're receiving a lot of information and I see that you hate getting this abundance so take as much time as you want while analyzing Rory's test methods and antenna problems. Oh the basic electro-mechanical specifications were not on the manufactrure's website when I started to try and help answer Rory's second Post.

73,

Dan
WA9WVX

kb1rbz
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Location: palmer,ma

vswr meter

Post by kb1rbz » Tue Nov 11, 2008 4:20 am

OK , first off all I wanted to know was if I could use a swr meter from CB radio on 2 meters. The question was appropriately answered. I thank all for this as the problem has been solved with the purchase of a meter designed for 2 meters. Second my post regarding high swr on the j pole was separate and had nothing to do with the first. Third the feed line is obviously not the problem as my vswr is a 1.1:1 on my 1/4 wave vertical using the same feed line. Care to explain this one?And last I would like to know how WA9WVX seems to know so much about my business as it was not publicly posted.
KB1RBZ

K4ICL
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Let there be some light, please...

Post by K4ICL » Tue Nov 11, 2008 1:33 pm

Rory:

Have you tested your feed line? This is easy to do. Just attach a known-good 50 ohm dummy load on the antenna end of the line and check the SWR (VSWR) by loading your transmitter into the dummy load, through the feed line. The SWR should be 1:1 or nearly so.

To test the SWR meter, place a known-good 50 ohm dummy load on the output (antenna) connector of the SWR bridge and transmit. It should ALWAYS be 1:1 SWR ratio if the meter is working properly.

All the rest of the "noise" appearing on this topic has generated much heat and very little light.

Cheers,

AL
K4ICL

KC6NEN
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Re: swr meters frequency specific?

Post by KC6NEN » Thu Feb 16, 2017 6:09 pm

I've found One CB VSWR model to work quite accurately at 2 M. Don't recall the make.
An HF meter I have (80-10 m) works at 70 cm but Not at 2m. (???)

Right, most won't.

Query: Is the difference basically higher frequency diodes? Or, can the stub be shortened so as not to affect the reading above its intended use?

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