Question about MFJ 1750 Base antenna, 2m, 4ft, w/ground plane

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How to installand andadjust swr - MFJ 1750 Base antenna, 2m, 4ft, w/ground plane

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The antenna you purchased has an adjustment to minimze the Standing Wave Ratio (SWR). Yo uwill need a SWR meter to measure the reflected power which is inserted in the coax line to measure the ratio. If the antenna uses 50 ohm coax make sure you use RG-8 instead of RG-58. A good SWR ratio is 1.1 to 1.. When I was on 2 meters after adjusting the antenna to obtain the lowest SWR we would trim the coax to a multiple of the transmit wavelength to get optimize it. A 2 to 1 ratio means you are relecting 1/2 of your transmitting power in the coax., hence a 100 watt transmitter is effectively only radiiating 50 watts from the antenna,. If it measures around 1.1 leave it alone. Adust it for the frequency you will be using the most because when you change frequency the SWR will be different.

Posted on Apr 02, 2015

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Posted on Apr 02, 2015

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Have a new cobra 29lx. Everthing works fine except for the SWR meter. Can't use the meter to adjust SWR. No matter what I do the meter stays the same. Sent to factory but they said nothing was wro


The SWR cannot be changed by rotating this knob. The SWR function allows you to determine the SWR or "match" of the antenna system and transmitter on a specific channel. The entire process must be performed whenever you want to know what the SWR is on a different channel. The SWR/CAL button toggles the meter between the CALIBRATE and SWR modes.
Set the radio to CH1. Press the SWR/CAL button. The radio CAL(ibrate) mode is now selected. Press and hold the mic PTT (or push to talk) button. Rotate the SWR knob as needed to adjust the meter indicator until it is on the SET mark on the dial. The meter is now calibrated for this channel.

While still holding down the mic PTT, press and release the S/RF SWR CAL button to the SWR setting to read the SWR on the meter.



This entire process should be done for Ch 20 and Ch 40. You must go through the CAL procedure for EACH channel before attempting to read the SWR.


Changing the SWR requires that the antenna be lengthened or shortened until such time that the SWR can be reduced no further. Typical SWR across the band may be:


CH1 - 1.5:1, CH20 - 1.1:1, CH40 1.5:1


or


CH1 - 2.2:1, CH20 - 1.7:1, CH40 2.3:1


The "dip" in SWR on CH20 is typical, as the antenna is the perfect length on only one channel - it will be come slightly too long or slightly too short as you tune up or down from CH20. The further away from CH20 you go, the poorer the SWR will be. You can "slide" the dip to any channel you prefer - say CH8. If you tune for lowest SWR on CH8, You might see CH1 with a 1.2:1 SWR, CH8 at 1.1:1 SWR and CH40 at 2.5:1. All are acceptable - sort of. Many manufacturers say up to 2.5:1 or even 3.0:1 matches are ok, There's no reason a quality antenna can't be tuned for optimum SWR in the middle of the band (CH20) to have less than a 2.0:1 SWR on CH1 or CH40, unless there is a ground issues or bad cable / antenna / connection somewhere.


You can view the manual here. I hope this helps & good luck!

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1 Answer

Self adjusting SWR does not work on 959 Galaxy


the swr on the radio is not what you are thinking it is. You have to set the SWR to anything below a 2.0 and the meter will let you know when and if your swr gets to high.

Sep 23, 2012 | Galaxy Radios DX-959 CB Mob Auto Swr...

1 Answer

Swr meter not moving


follow these steps to adjust the
standing wave ratio(SWR).
1. Turn on the CB.
2. Set S/RF/SWR/CAL to CAL.
3. Key the Mic and rotate SWR CAL so the meter points
to CAL.
4. Unkey Mic.
5. Set S/RF/SWR/CAL to SWR.
6. Key Mic again and note the actual measurement on
the SWR scale. Refer to the following table to interpret
the reading.

1:1 - 1.5 Great
1.5 - 2:1 OK
2:1 - 3:1 Not So Good
Higher than 3.1:1 Terrible

Jan 14, 2011 | Cobra 29 LTD CB Radio

2 Answers

Tunning the antenna on radio shack cb trc-447


After installing the antenna, follow these steps to adjust the
standing wave ratio(SWR).
1. Turn on the CB.
2. Set S/RF/SWR/CAL to CAL.
3. Key the Mic and rotate SWR CAL so the meter points
to CAL.
4. Unkey Mic.
5. Set S/RF/SWR/CAL to SWR.
6. Key Mic again and note the actual measurement on
the SWR scale. Refer to the following table to interpret
the reading.

1:1 - 1.5 Great
1.5 - 2:1 OK
2:1 - 3:1 Not So Good
Higher than 3.1:1 Terrible

The ideal standing wave ratio (SWR) is 1:1, or a meter
reading of 1 on the SWR meter's top scale. A SWR ratio
of 1.5:1 to 2:1 is excellent for most mobile CB antenna
applications.

Check the SWR on Channel 1 and Channel 40
If the SWR is higher on 1, make the antenna longer
If the SWR is higher on 40, make the antenna shorter
Most antenna's are adjustable. Make small adjustments at a time.

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2 Answers

When i key up the mike the tx/rx light and the ant


your swr setting are off wack fix your swr

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2 Answers

I need the manual/s for a Cobra CB radio, 29LTD Classic,ser#105129711,manufactured 5/01. Thanks for any help you might have, This radio has a built in SWR meter and I need to know how to tune it or do I...


1) push the button marked S/RF / SWR / CAL to CAL

2) Hold in the button on the mic

3) Turn the SWR CAL knob until the needle is over set to the far right of the meter

4) flick the switch (in step 1) to SWR

Your SWR reading will be displayed. The more to the left the better..

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2 Answers

Swr to hi and can t get it down


I hope this will help you on setting your swr put the radio on channel 1 check your swr.
now go to channel 40 check the swr. If the swr is lower on 1 than it is on 40 the antenna must be shortened buy 1/4 inch.until you reach your desired swr.if the swr is lower on 40 than it is on 1 the antenna must be lenthened by 1/4 inch until desired swr.

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Are you registered in Administrative groups as an administrator for the PC? If not, you can go to Administrator Tools in Control Pannel and change in include youruser name in the Computer Administrator group, that wayit will allow you to installand change confugurations.

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