Spectrum Analyzer + Power Attenuator

[mvrx]

Hello guys,

I was wondering if I can (and if it's also safe to) use my Rigol DSA815 (or any spectrum analyzer) in conjunction with a power attenuator (30dB/150W) to measure amateur gear's power output.

Has any of you tried to measure power output this way?
Can you give me an example of how to hook up?

Thank you.

Regards,
Raz

 

[zz0468]

It's not an accurate way to measure power, but it can be useful. Just make sure that the total attenuation between the transmitter and the spectrum analyzer is enough to reduce the signal to a safe level.

But don't expect any highly accurate power measurements that way. For that, you need a power meter.

 

[prcguy]

As ZZ says its not the most accurate because spectrum analyzers generally have very good relative amplitude accuracy as in per division, but the absolute accuracy can be off by +/- 1dB or more depending on model and frequency.

The 30dB attenuator will knock 100w down to 100mw or 20dBm, which should be safe for most analyzers but you should make sure your analyzer is working within its linear range and at least 10dB below the compression point of the analyzer.

The power attenuator accuracy will also affect the end reading on the analyzer or power meter but if you can get a swept response of the attenuator and you happen across a good power meter some day you can make very accurate RF power measurements.
prcguy

 

[mvrx]

Thanks for the replies.
Actually, I do have a service monitor (IFR COM-120B) which can act like an accurate power meter. I just wanted to know if there's a good idea to use my other tool, the spectrum analyzer to measure high power devices.
It looks like it's not, so I'll just stick to my Telewave 44AP power meter and IFR SM.

Once again, thanks for your time.

Regards,
Raz