mfj 259b

[hotrod]

just got this thursday and been checking all my antennas.my 2016 reads
swr 1.1
R=48 -49
X-=2
way i understand it this is good right???
on my mobile
swr=2.5
R=36?? I THINK
X= 20 if i remember right
the mobile reading were much higher i cant remember if the R ,X numbers exactly
as its been two days but think im pretty close.heres funny part if i use my mfj
swr meter with radio,jumper the meters reads about a 1.5-1.7??????
i tend to wanna believe what the 259 reads maybe im wrong i thinking way
what you guys think?if i have to i,ll recheck the moblie again if it stays nice outside

 

[GnG8d]

i tend to wanna believe what the 259 reads

Because you paid more for it :laugh:

 

[W5LZ]

I would say your '259 is reading correctly. An SWR meter can be fooled because it doesn't recognize reactance (that X number). There are many combinations of R and X that will make an SWR meter read something good when it isn't good. Wanna know why? Then dive into AC electricity and learn about impedance.
- Doc

 

[Marconi]

just got this thursday and been checking all my antennas.my 2016 reads
swr 1.1
R=48 -49
X-=2
way i understand it this is good right???
on my mobile
swr=2.5
R=36?? I THINK
X= 20 if i remember right
the mobile reading were much higher i cant remember if the R ,X numbers exactly
as its been two days but think im pretty close.heres funny part if i use my mfj
swr meter with radio,jumper the meters reads about a 1.5-1.7??????
i tend to wanna believe what the 259 reads maybe im wrong i thinking way
what you guys think?if i have to i,ll recheck the moblie again if it stays nice outside

I'm just guessing at what you tried to say Hotrod, but if you change the feed line length and you see a difference...your antenna is reactive. It is either capacitive(-) or inductive(+)...just like your numbers suggest. To prove it just remove the meters. Try a reading without the meters and with the jumper back in line. You may miss the minimal effects of the meter(s), but you should see the 259B return to a reading closer to the original results...I would think.

The analyzer is affected by the feed line much like an in line meter will be unless your 259B has a feature setting that can calculate and consider the 1/4 frequency length between the 259B and the antenna in its scan of the feed point. How much difference this can make depends on the magnitude of the reactance and the phase. There are hundreds of SWR variables in such a scenario unless the match is at or near perfect.

My Autek meter has such a function, and it is referred to as the F-1/4 Function.

You might look for a similar type of function in your owner's manual.

View attachment Autek VA1.pdf

View attachment Autek VA1 pp2.pdf

 

[hotrod]

I would say your '259 is reading correctly. An SWR meter can be fooled because it doesn't recognize reactance (that X number). There are many combinations of R and X that will make an SWR meter read something good when it isn't good. Wanna know why? Then dive into AC electricity and learn about impedance.
- Doc

thank you. ive heard that before about you could have a bad swr but meters reads otherwise
guess i got some tuning to do on my mobile.

 

[boomer111]

I have found the MFJ 259b to be very sensitive picking up reflect. Antenna location on a mobile is paramount for all around excellence.

I have a 22" bottom shaft on a open coil antenna. I got my best readings by moving the coil up from 12". Also location of said antenna on vehicle plaus a important in achieving best possible match.

The 259B will respond to small antenna changes regarding length and position etc.

I like to use the Reflect Coefficient mode in the advanced section for fine tuning. Higher the minus db value the better. -48 db is the best. I feel good with anything bouncing above -36 db. while running a 4 pill.

Have fun it can become addictive.

I also adapted a 12 volt plug for mine. This meter will drain batteries quickly and the higher constant voltage gives more reliable readings.

 

[cbradiomagazine.com]

The 259B really is a great tool - after using it for a while you'll never get rid of it.