How much power is 1V ?

[HiTower]

I found a piece of test equipment laying around the shop, which states Max RF input 1V ... What does that mean. Isn't RF usually measured in watts or dB's ?

 

[HOMEYD]

> I found a piece of test equipment laying around the shop,
> which states Max RF input 1V ... What does that mean.
> Isn't RF usually measured in watts or dB's ?
>


1 Volt = 20 milliwatts = 13 dBm(decibel(m)reference level used)

 

[Les]

> I found a piece of test equipment laying around the shop,
> which states Max RF input 1V ... What does that mean.
> Isn't RF usually measured in watts or dB's ?

RF output is generally expressed as you state. But those are expressions of power, not to be confused with voltage. P=IE where the same "P" (power or wattage, etc.) can be achieved through various combinations of "I" (current or Amperage) and "E" (Voltage). For example, to get to 20 Watts you might have 20 Amps at 1 Volt. Or 4 Amps at 5 Volts.

The test equipment marking is telling you that the internal circuits are rated for no more than one volt. Generally test equipment for RF does not expect to be the termination of the load; rather to bridge the load so the power is directed to a dummy or real antenna. Only a sample is sensed. The voltage of the sample to be 1-Volt or less, in this case, with anything higher exceeding the maximum ratings of components within the test instrument.


<P ID="signature">______________
It is hard enough to remember my opinions, without also remembering my reasons for them! (if any)
--Friedrich Nietzsch</P>

 

[rbrucecarter]

> 1 Volt = 20 milliwatts = 13 dBm(decibel(m)reference level
> used)

BE CAREFUL! You are assuming 50 ohms impedance, which may or may not be the case. Also - is it 1 Vpp or 1Vrms or 1 V peak?

I got so tired of this problem that I created a little javascript to take care of it. My company like it so much they posted it:

http://www-k.ext.ti.com/srvs/cgi-bin/webcgi.exe?Company={5761bcd8-11f5-4e08-84e0-8167176a4ed9},kb=analog,case=obj(32624),new

If you can enter in that stupid long URL, it comes up in a knowledgebase FAQ format.

 

[PhilJSmith67]

http://www-k.ext.ti.com/srvs/cgi-bin/webcgi.exe?Company={5761bcd8-11f5-4e08-84e0-8167176a4ed9},kb=analog,case=obj(32624),new
>
> If you can enter in that stupid long URL, it comes up in a
> knowledgebase FAQ format.

Hey that's quite useful. Thanks Bruce! As for the typing, I clicked on your link and saved it as a shortcut.

 

[HOMEYD]

> > 1 Volt = 20 milliwatts = 13 dBm(decibel(m)reference level
> > used)
>
> BE CAREFUL! You are assuming 50 ohms impedance, which may
> or may not be the case. Also - is it 1 Vpp or 1Vrms or 1 V
> peak?
>
> I got so tired of this problem that I created a little
> javascript to take care of it. My company like it so much
> they posted it:
>
http://www-k.ext.ti.com/srvs/cgi-bin/webcgi.exe?Company={5761bcd> 8-11f5-4e08-84e0-8167176a4ed9},kb=analog,case=obj(32624),new
>
>
> If you can enter in that stupid long URL, it comes up in a
> knowledgebase FAQ format.
>

Guilty. I did assume the 50 ohms. Most of my RF test gear is.

Thanks for the link...NICE!

 

[TXengineer]

1000 millivolts? (Sorry bad engineer humor) (No Text)

> I found a piece of test equipment laying around the shop,
> which states Max RF input 1V ... What does that mean.
> Isn't RF usually measured in watts or dB's ?
>