how to read swr on a palstar pm2000a

[BOOTY MONSTER]

so i see these dual needle meters are recomended a lot . i also never read any bad comments on the palstar meters . but......how do you read the swr on a dual needle meter ????

http://www.palstar.com/pm2000a.php

 

[GLR]

swr is read where the needles cross on the marks at the bottom of the meter

they work fine

 

[Beetle]

The scale with the red lines -- the one labelled "SWR". Read it right where the needles cross.

 

[74IN]

Simple, reflect needle low, good, needle high, bad.

I have Mighty Fine Junkers, I relly like seeing the reflect without screwing around with a calibrate adjustment.

 

[74IN]

The active peak is cool, but I wonder if it's really needed.

I doubt most applications need to be absolutely accurate (none are), any decent meter will suffice.

I didn't see any specs for accuracy, so it must not be an issue.

 

[W5LZ]

Booty M',
I think you've probably got the idea at this point so won't tell you how to read a cross needle meter. I do like them, they're a sort of 'hands free' kind'a thingy, don't have to switch between forward power and reflected power or SWR, you see the whole mess at one time.
Are they more accurate than other meters? No, not any more accurate than the manufacturer makes them / calibrates them, and since they use a mechanical meter movement, figure something in the 10% accuracy range (same for ALL mechanical meters). Are they easier to use? They certainly are for me! Don't have to remember if I switched it to read something other than what I wanna read now.
I don't own a 'Palstar'. I've got/had a couple of the MFJ meters. Better? Not really, just cheaper and they do the same things. I've found that 'status symbols' are very low on the list of thingys I just gotta have. That 'status' doesn't 'do' anything except cost more.
One other thing, not all that important except to me. The movement of a needle tells me as much as the number it points at when it's stopped moving. It shows 'trends' when making adjustments, faster recognition of going in the wrong direction, sort of. (Does NOT mean that there's anything wrong with 'digital' meters! I just don't find them all that useful.)
Do you like the Palstar? If so, then why not? Like something else better? Get that instead...
- 'Doc

 

[Beetle]

74IN - It would be interesting to check the maximum error on a dual needle SWR meter under different conditions. Typically, instrument accuracy/precision is a direct function of the number of moving parts.

Since a dual-needle instrument relies on two independent d'Arsonval meter movements, each one with a typical max error of +/- 10%, the worst-case would be twice the max error of one movement, or +/- 20% of full scale reading.

Of course, you can't verify that without going through a fairly expensive calibration and adjustment procedure. It'd cost more than a new Palstar, that's for sure.

 

[W5LZ]

Since each meter is only operating in one 'direction', the total is still 10% +/- whatever. Can't add those two to make 20% error, they would 'cancel', IF they both had the same amount of error. If one had slightly more/less than the other, then the total would be whatever that difference would be. And on the practical side of things, what difference would it really make?
- 'Doc

 

[Beetle]

Meters are generally spec'ed at "plus or minus X% of full scale deflection"; it doesn't matter if they are the "zero center" type. If they are both off in the same direction, the total max error adds, and that's the way a calibration lab would label a cross-needle instrument. The +/- 20% of FSV doesn't come into play until you're measuring SWR. Each of the power meters, forward and reflected, has its own error band of +/- 10% FSV. When measuring a third value using these two meters, the total error has to add.

The Navy actually used the Daiwa line of meters when they first came out back in the 70s, until they realized that the Bird 43 was a better choice for lugging around on a ship, plus which the electronics mechanics already knew how to use the Bird!

 

[W5LZ]

Sorry, didn't mean the 'direction' the meter was moving, but the 'direction of voltage/current flow that it was measuring.
- Doc

 

[Beetle]

Ah! Got it now.

"Zero-center" meters are the worst things to try to calibrate/adjust. The return springs NEVER want to cooperate, but in the '60s/'70s, the labor cost to get a meter fixed properly was less than the cost of a brand new instrument complete with calibration certificate and printed specification list.

'Taint that way any more!