Astatic 600 swr/wattmeter ?....

[Oatmeal]

I bought this one new about 3 years ago now, and I have since then noticed the meters seems to be a little off....so I have talked to a guy who can recalibrate this meter and says he uses a Bird meter and checks the swr part with a dummy load....

So I wanted to no should I have it recalibrated, or buy another one ?..

Far as I can tell other than it needing recalibrated, dont look to be anything wrong with it..I do like the idea of been able to see what my swr is when I run my box as well as seeing the swing watts...

 

[BOOTY MONSTER]

dosey/astatic are all a little off , that's the nature of meters in this price range . even birds are supposed to be re-calibrated every 6 months (i think) . how does his bird get re-calibrated ?

why would your swr change when you run your box ?

 

[roadrage]

I bought this one new about 3 years ago now, and I have since then noticed the meters seems to be a little off....so I have talked to a guy who can recalibrate this meter and says he uses a Bird meter and checks the swr part with a dummy load....

So I wanted to no should I have it recalibrated, or buy another one ?..

Far as I can tell other than it needing recalibrated, dont look to be anything wrong with it..I do like the idea of been able to see what my swr is when I run my box as well as seeing the swing watts...

I guess that would depend on how much it is going to cost to recalibrate it. Honestly, if he can callibrate it well it might read better than a new one. All meters read differently, and most of the test equipment that us non-technicians can afford is more of a ball park anyway.

dosey/astatic are all a little off , that's the nature of meters in this price range . even birds are supposed to be re-calibrated every 6 months (i think) . how does his bird get re-calibrated ?

why would your swr change when you run your box ?

That is something that I have seen many people say happens, and other people say that it can't. I witnessed it happen when I went to a high power radio and watched the SWR go from not moving the needle on low power on my radio's internal meter and external, to a 1.4 using the radio's meter and 1.15 on the external with the radio on high. So with the power on high there is a slight variation even on the external meter. Why it happens? I have my hypothesis that it may be due to coax that is fine for stock power but substandard for the added fire. It is something I plan on testing out someday. Another thing is that more power may cause more reflection or reactance with objects outside the radio/antenna system. But I am just a operator not a tech, so until I can test my theory; my assumption is just that.

 

[Highlander_821]

I have an Astatic 600 that has always been stingy, especially for AM.

 

[sp5it]

http://www.worldwidedx.com/meters-mics-other-accessories/140263-calibrate-astatic-600-meter.html

 

[Beetle]

dosey/astatic are all a little off , that's the nature of meters in this price range . even birds are supposed to be re-calibrated every 6 months (i think) . how does his bird get re-calibrated ?

why would your swr change when you run your box ?

There's a LOT more involved with calibration than simply comparing two different meters. That guy's Bird (probably a Model 43) is only ±5% max error anyway, and that's only true for six months after purchase or after a VALID recalibration, like Booty said.

 

[Oatmeal]

The meter, best I can tell it shows about 75 watts less than it should...
I dont no how he recalibrates it with his Bird meter...all I no is it need calibrated...Ive put the needle off the scale and n the corner a few times...

Thw swr, it changes maybe 1 numbers between when I barefooted and the kick the power on....nothing like it used to be...got the swr under control now..

Ive been looking at a radio shack swr/watt meter this one has the 200w scale and a 2kw scale...wonder how accurate it would be ?..

 

[Robb]

The one limitation of this Astatic meter, is that it can only give you a fairly accurate AVG power reading. Because this meter is not a TRUE PEAK POWER reading meter - by design. It does not have a peak reading circuit in it.

If you have someone that can align it; then by all means do so. Just don't expect this meter to give a true peak power reading - is all . . .

 

[TonyV225]

I can tell you one thing forsure.....I have had several of these meters and the alike and not 1 meter read the same as any of the others!!! They each read differant readings no 2 were on the same page as far as power measurements.

You can have it alligned but it still will never show you a true peak if thats what your after because of the circuitry they use and even the average peak may not be exactly spot on but they can be pretty close as far as Standard avg/peak readings.

All in all they are what they are and you cant expect (True Magic) from them but they can be ok for basic idea or reference to whats happening. If you want true readings in the standard AVG/PEP department the go to Radio Shack and get yourself one of these 21-534 CB/High-Frequency Ham Power SWR Meter - RadioShack.com

They are reliable and not full of $h!+ I use them on the Amateur bands They actually use the same circuitry as the Yaesu meters use I know other operators that use them aswell as a matter of fact I have 4 of these and just borrowed one out to another amateur operator friend of mine.

 

[roadrage]

The one limitation of this Astatic meter, is that it can only give you a fairly accurate AVG power reading. Because this meter is not a TRUE PEAK POWER reading meter - by design. It does not have a peak reading circuit in it.

If you have someone that can align it; then by all means do so. Just don't expect this meter to give a true peak power reading - is all . . .

I was acually just reading about this subject and you are right. Most meters that are affordable to the common operator are RMS meters. The "peak" setting on this meter will read peak RMS, not true peak to peak. For a meter to read true peak to peak or for it to read peak envelope power, it needs a powered circuit to do so. Other wise it will be too slow for any accurate reading. And these are much more expensive. But ave RMS and peak RMS are good enough for us to get an idea of what our radios are doing. Bird meters have a powered circuit and have the ability give true peak to peak readings, but even they are +/- %5 accuracy.

 

[Captain Kilowatt]

I was acually just reading about this subject and you are right. Most meters that are affordable to the common operator are RMS meters. The "peak" setting on this meter will read peak RMS, not true peak to peak. For a meter to read true peak to peak or for it to read peak envelope power, it needs a powered circuit to do so. Other wise it will be too slow for any accurate reading. And these are much more expensive. But ave RMS and peak RMS are good enough for us to get an idea of what our radios are doing. Bird meters have a powered circuit and have the ability give true peak to peak readings, but even they are +/- %5 accuracy.

Not to be picky but there is no such thing as RMS power. It is AVERAGE power. Oddly enough RMS voltage times RMS current yields AVERAGE power not RMS power which is a misnomer. As for the Bird meters, only the peak meters have the proper circuitry to detect and display true peak power. The average reading Bird meters have +/-5% accuracy while the peak reading Bird meters have only +/-8% accuracy.

 

[AudioShockwav]

Not to be picky but there is no such thing as RMS power. It is AVERAGE power.

So Right.
If you search here on the forum, you will find links that I have posted that will tell you what RMS, Peak and AVG power is.
The Bird 43 reads AVG power, and if you install a peak kit in it, will read Peak power.
There is no such thing as a RMS watt in RF, it is a improper term that Dosy has pasted on the front of there watt meters for years and Audio enthusiast Have coined and used for a long time.


And Captain, I was on 3.846 late last night listening to 3 or 4 guys taking about the AL-80 one of them was using....another ham piped in a and asked " how many watts will it do RMS" the Frequency went dead silent for several min....he asked again...some one said " here we go"

73
Jeff

 

[AudioShockwav]

http://www.eznec.com/Amateur/RMS_Power.pdf


Cliff notes:

It should be noted that the term “RMS power” is (mis)used in the consumer audio
industry. In that context, it means the average power when reproducing a single
tone, but it’s not actually the RMS value of the power.
Summary
I’ve shown that:
 The equivalent heating power of a waveform is the average power.
 The RMS power is different than the average power, and therefore isn’t the
equivalent heating power. In fact, the RMS value of the power doesn’t
represent anything useful.
 The RMS values of voltage and current are useful because they can be used
to calculate the average power.
For those who are interested, mathematical derivations are readily available and
can be found on various web sites and in textbooks. What I’ve tried to do here is
to present the basic concepts with as little mathematics as possible. Questions
are welcome – send them to w7el@eznec.com. And I’d appreciate very much if
anyone finding an error would notify me so it can be corrected.
Roy Lewallen, W7EL
.

OK, aside from incorrect term`s used by the makers of watt meters, what the basic concept of most of the watt meters used in the Amateur and CB radio service are not that Accurate.
If you are worried about a 10/15% error at full scale on your meter it really is not that critical and you should not be.
IF you had a Broadcast Lic, and needed to verify power output then you should be concerned about how accurate you test equipment should be.
Even the World renowned Bird Watt meter can show various levels of power, and is subject to error.
Slugs can be damaged, meters can be dropped and effect operation.
As One of the members has already Said, if you are in the Service ( Army/Navy/Air Force) there are rigorous standards that must be adhered to.
I used to have test equipment that had NASA calibration stickers on them.
They had a date when they were last tested, and when they were required to be tested again...
Outside of the service, I doubt there will be a time you go into your local HAM/CB shop and be shown a Meter with a BIRD or NASA calibration sticker on it because we do not need that kind of accuracy.

Here is an example of the Bird with A Peak kit on it, and how a simple thing like Speech processing can effect it.

http://vk1od.net/measurement/SsbTxPower/MeasureSSBTxPower.htm
If you need CRITICAL power measurements there are other way to measure power that are more " accurate"

I would not worry about it too much....most watt meters used in the radio we play are close enough.


73
Jeff

 

[Captain Kilowatt]

And Captain, I was on 3.846 late last night listening to 3 or 4 guys taking about the AL-80 one of them was using....another ham piped in a and asked " how many watts will it do RMS" the Frequency went dead silent for several min....he asked again...some one said " here we go"

73
Jeff

Maybe he was wondering about "Bird watts" while using the Right-Meter-Scale.

 

[Beetle]

Another misunderstood term used here is "peak-to-peak". This refers to the peak value of the waveform ABOVE the X-axis plus the peak value of the waveform BELOW the X-axis during one complete cycle. For example, two volts above plus two volts below equals four volts p.p.

Peak to peak has pretty much nothing to do with the output of an amplifier except voltage amplifiers in oscilloscope circuits, generally.