SWR

[Swamp Yankee]

Hello All,
Another question. When tunning an antenna, should there be (can there be) anything else installed in-line between the radio and the antenna other than the SWR meter? If there were any other accessories would this effect the SWR reading? Thanks...

 

[Xracerx13]

(can there be) anything else installed in-line between the radio and the antenna other than the SWR meter? If there were any other accessories would this effect the SWR reading?

The SWR meter should be last in line before the antenna

 

[FlatlandBusa]

Yes, there you can have an antenna matcher (tuner) between the SWR meter and antenna. My current equipment lineup is: radio - grounding switch - linear - SWR/power meter - antenna matcher - lightning arrestor - antenna.

If all equipment in line has a characteristic impedance of 50ohms and the antenna matcher is in bypass the SWR reading shouldn't be affected.

 

[BC Coyote]

If you use an outboard phase-cancelling noise eliminator (such as MFJ-1026), that would also be placed in the coax between the radio and antenna. If an amp is used it would be placed between the amp and antenna. It doesn't really matter if the noise cancelling box is before or after the SWR meter.....

A word of caution.....most of those type of devices are rated at 100 watts max throughput, so if you run a big amp, using one is pretty much out of the question.

I have a nice Daiwa SWR meter, but I don't keep it in-line. I use it after I make any major changes to my antennas, and after that I unhook it and put it away. My antenna tuner has a decent built in SWR/power meter and under normal daily operating conditions that is what I rely on.

My number one setup is a Kenwood TS140S straight into a Kenwood antenna tuner/antenna switcher and then to one of two antennas.
Number two setup has a Cobra 148GTL into a A/B biased Palomar 200 and then into the same Kenwood antenna tuner/switcher from there. I'm a big believer in having as little as possible in between the radio and antenna !

 

[Xracerx13]

When tuning an antenna by raising or lowering or cutting the whip.... the SWR meter has to be last in line period.

 

[BC Coyote]

When tuning an antenna by raising or lowering or cutting the whip.... the SWR meter has to be last in line period.

Nope. In that case you want the SWR meter as close to the radio or amp output as possible. The further away from the amp or radio the meter is, the more inaccurate the reading.......
Best way to do it is to remove ALL extra equipment and just do the measurements while using ONLY a radio and an SWR meter. Once the match is as flat as possible, the other equipment can be hooked back up. If the match changes when you hook up your other equipment, it means you have common mode currents (CMC) on the antenna coax, often caused by the lack of a balun or a proper ground.

 

[Xracerx13]

Nope. In that case you want the SWR meter as close to the radio or amp output as possible.

I wasn't suggesting that the swr meter be in the trunk of the car the way you make it sound so far from the radio or amp.. What I was trying to suggest is that the meter be the last thing before the antenna cable whether or not there is an amp/filter/etc after the antenna is tuned.
It is true that the best way to tune an antenna is just the radio with a 3ft jumper to the SWR meter and then have the antenna hooked up to the meter output.
We don't know what he has so there is no reason to assume and add a hole bunch of stuff to confuse him.

To answer the OP's first question. The answer is NO. The swr meter(only) has to be between the radio and antenna

 

[Swamp Yankee]

Thank You Gentlemen....What a great place to get help/information!