8
$\begingroup$

There are SWR/power meters with two separate gauges, and others that have them mounted so the gauge needles cross over each other.

Aside from looking cool, does the cross-over point of the two meters provide specific or useful information?

Improve this question
$\endgroup$
0

2 Answers 2

Reset to default
10
$\begingroup$

A cross-meter is capable of showing you three measurements simultaneously:

  • Output Power
  • Reflected Power
  • SWR

From this image by Axel Schwenke on Wikipedia, you can see that the needle on the left indicates forward power, and the needle on the right indicates reflected power. The observed intersection of the two needles can be used to indicate the SWR of the system. The lines in the middle of the meter indicate what the SWR is for a given forward and reflected power reading.

cross-meter

Improve this answer
$\endgroup$
1
  • $\begingroup$ Exactly. It prevents having to flip a switch between FWD/REV in order to read the SWR. And as an added bonus indicates power. Upvote. $\endgroup$
    – SDsolar
    Apr 29, 2017 at 21:28
6
$\begingroup$

A properly calibrated cross-needle power meter such as e.g. the MFJ-842 actually tells you something more than just the forward and reflected power, which as you point out can just as easily be indicated by two separate instruments.

The intersection of the needles gives you a pretty good indication of the actual standing wave ratio or SWR because the SWR is directly related to the relationship between the forward and reflected power.

So, there's more utility to this than simply "saving space" or "looking cool". Of course, you could have a third meter showing the resultant SWR based on forward and reflected power indicated on two separate instruments, but why bother when you can put all the information into one and at the same time reduce the risk of measurement inconsistencies?

Improve this answer
$\endgroup$
0

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .