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Author Topic: 6 meter swr  (Read 5430 times)
N0SOY
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Posts: 72




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« on: August 21, 2012, 10:12:19 AM »

I am setting up a 6 meter dipole and I need to check the swr of the system.   My meters are advertised for 1.6 to 30 Mhz and 144 to 220.  Can I use one with reasonable accuracy to test the system or will have have to get another one.  I do have an antenna tuner a Mfj 941e but the specs do not cover 6 meter. 

Any ideas?
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KA4POL
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Posts: 2098




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« Reply #1 on: August 21, 2012, 10:42:22 AM »

It is very hard to say how good your measurements will be. Some meters may deliver fair results, some not at all. Perhaps you could try a dummy load first.
The tuner can't be used, you are over 20 MHz above the spec.
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WB2WIK
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Posts: 20636




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« Reply #2 on: August 21, 2012, 10:55:32 AM »

What, exactly, is your 6m transmitter?
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G0VKT
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Posts: 64




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« Reply #3 on: August 21, 2012, 03:01:27 PM »

What sort of meters do you have?

Cross needle or single/ dual meter where you set forward power with a knob?

If you let me know it will save a long winded reply.
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K2OWK
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« Reply #4 on: August 21, 2012, 04:27:51 PM »

I have a MFJ 815B cross needle SWR/Wattmeter. I use it on 6 meters with no problem. I also have a MFJ-914 Auto Tuner Extender that works OK on 6 meters. I checked with MFJ about this and the tech. told me that it will work on 6 meters as a reference, but the accuracy will be down. I really do not need the accuracy, just the power out vs the VSWR, it does this OK. The MFJ-914 does allow my internal tuner to tune the entire 6 meter band on my inverted "V" which without it will only work on the center of the band where I set it.

Hope this Helps.

73s

K2OWK
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N0SOY
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Posts: 72




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« Reply #5 on: August 25, 2012, 11:04:41 AM »

I have a mfj 9406 12watt ssb transceiver.   The tuner I have is a 941e and the two swr meters are the mfj 2mter and HF meters (the basic ones) the antenna is a rotatable dipole with 2 hamsticks for 6 meter or a vertical mag mount ( that one will not need the tuner just an swr meter)

Hope that information helps.
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N0SOY
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Posts: 72




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« Reply #6 on: August 25, 2012, 11:06:32 AM »

the two swr meters are single needle knob adustment.

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WB6BYU
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Posts: 13488




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« Reply #7 on: August 25, 2012, 11:22:06 AM »

Either meter is probably close enough to get a "low" SWR, even if they aren't precise as to
how low it actually is.  In your case, you'll adjust the length of the antenna for minimum,
and they should be able to show that reasonably well.  When in doubt, put both meters
in series, and if they agree on "low", then you're good.

I use the cheap meters designed for CB use on 80m through 2m.  They are adequate to
show "low" or "high", and that's usually good enough for my purposes.
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G0VKT
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Posts: 64




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« Reply #8 on: August 27, 2012, 04:23:38 AM »

I am also using a cheap dual meter CB SWR meter from 160 to 2m.
Good enough for me and compares well enough to a more expensive one.
I only run a maximum of 100W.
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KM3F
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Posts: 523




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« Reply #9 on: August 27, 2012, 09:52:26 AM »

Dave , here is something to consider when using any SWR meter.
No matter;-----when the reverse indication gets down very low, there is not much reflected power causing the meter to read.
So it does not matter if the meter is accurate or speced for that frequency since the reading is close to zero for a match anyways.
Just don't always depend on the meter for accuracy at higher readings.
It's near zero that counts the most for what your trying to accomplish.
.
There are two major meter designs.
A stripline and a toroid type.
With the  stripline like the old CB types, they are frequency sensitive due to the stripline length vs F.
They work over a wide range such that on 6m the stripline length vs frequency get longer so the sensitivity should increase but still makes them very usefull even though the absolute meter accuracy may not hold.
.
The torrid type which more modern units uses are more broadbanded and compact but can still be frequency sensitive to F when the frequency gets above 6m.

Bottom line is when the reflected reading gets near zero, your match should be good enough on most all meters unless the sensitivity gets so poor it's not usefull.
There is another way for you to use.
A noise bridge will be the ticket to adjust in any antenna and uses no transmitter power at all, just your sensitive receiver.
A noise bridge cost no more than a low end SWR meter and is so usefull for these things when you need it.
They have two setting to use. One is resistive and one the impedence sign.
All you do is adjust the antenna or tuner for Z=0 or very close and R=50 for min noise in the receiver and you have a match better than an SWR can show..
Good luck..
« Last Edit: August 27, 2012, 10:03:29 AM by KM3F » Logged
AD4DQ
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Posts: 11




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« Reply #10 on: October 04, 2012, 07:28:45 PM »

Very interesting post. With my gear I can use my SWR meter that is specked for 160-10 meters on 6 meters and it reads accurate to my MFJ 906. As the previous post states if the match is close or 1-1 there is no reflected power to move the meter and you will show a very low SWR. For a Dipole I cut mine to 52 inches per side, it is 1-1 swr on 50 and 51MHZ I havent checked it on 52 and 53 since I dont do much FM work.
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