Measure RF Power at 900MHZ
 

Hi,
I have 20 900MHZ ISM band modules and I would like to measure RF
power. I have a a Tektronix 2712 Spectrum Analyzer and some
attenuators(BNC) and RG 58 coax. Unfortunately I do not have an SMA
connection on the antenna port. there are pads for the antenna that I
could fit an SMA to but I none of the ones I can find fit quite right
because of physical interference with the RF shield.

I tried soldering the RG 58 coax to the signal and ground pads but the
signal was not visible at the spectrum analyzer. I know RG 58 is lossy
but the Belden Coax calculator said I should lose about 20% of the
power at 1 mwatt.

Any thoughts or suggestions regarding coupling this signal (100 to
500mW) to a power measurement would be greatly appreciated.

Thanks,
Ed V.

depending upon the mode of operation of the module, it may be difficult
to see the carrier with your spectrum analyser. Most (not all) 900 MHz
ISM stuff is frequency hopped, so the carrier will dwell on a
partiucular frequency for only a short time. Also some of these devices
are polite and will not transmit in the blind so another modem must be
communicating with it. All this being said, you were really asking about
wiring up a coax cable to the module.

Soldering a small coaxial cable should be OK if you can get to ground
and antenna with very short connections. Keep in mind the loss of the
cable will be significant at 900MHz.

Ed Vogel wrote:

Hi,
I have 20 900MHZ ISM band modules and I would like to measure RF
power. I have a a Tektronix 2712 Spectrum Analyzer and some
attenuators(BNC) and RG 58 coax. Unfortunately I do not have an SMA
connection on the antenna port. there are pads for the antenna that I
could fit an SMA to but I none of the ones I can find fit quite right
because of physical interference with the RF shield.

I tried soldering the RG 58 coax to the signal and ground pads but the
signal was not visible at the spectrum analyzer. I know RG 58 is lossy
but the Belden Coax calculator said I should lose about 20% of the
power at 1 mwatt.

Any thoughts or suggestions regarding coupling this signal (100 to
500mW) to a power measurement would be greatly appreciated.

Thanks,
Ed V.



--
Joe Leikhim K4SAT
"The RFI-EMI-GUY"

The Lost Deep Thoughts By: Jack Handey
Before a mad scientist goes mad, there's probably a time
when he's only partially mad. And this is the time when he's
going to throw his best parties.

depending upon the mode of operation of the module, it may be difficult
to see the carrier with your spectrum analyser. Most (not all) 900 MHz
ISM stuff is frequency hopped, so the carrier will dwell on a
partiucular frequency for only a short time. Also some of these devices
are polite and will not transmit in the blind so another modem must be
communicating with it. All this being said, you were really asking about
wiring up a coax cable to the module.

Soldering a small coaxial cable should be OK if you can get to ground
and antenna with very short connections. Keep in mind the loss of the
cable will be significant at 900MHz.

Ed Vogel wrote:

Hi,
I have 20 900MHZ ISM band modules and I would like to measure RF
power. I have a a Tektronix 2712 Spectrum Analyzer and some
attenuators(BNC) and RG 58 coax. Unfortunately I do not have an SMA
connection on the antenna port. there are pads for the antenna that I
could fit an SMA to but I none of the ones I can find fit quite right
because of physical interference with the RF shield.

I tried soldering the RG 58 coax to the signal and ground pads but the
signal was not visible at the spectrum analyzer. I know RG 58 is lossy
but the Belden Coax calculator said I should lose about 20% of the
power at 1 mwatt.

Any thoughts or suggestions regarding coupling this signal (100 to
500mW) to a power measurement would be greatly appreciated.

Thanks,
Ed V.



--
Joe Leikhim K4SAT
"The RFI-EMI-GUY"

The Lost Deep Thoughts By: Jack Handey
Before a mad scientist goes mad, there's probably a time
when he's only partially mad. And this is the time when he's
going to throw his best parties.

depending upon the mode of operation of the module, it may be difficult
to see the carrier with your spectrum analyser. Most (not all) 900 MHz
ISM stuff is frequency hopped, so the carrier will dwell on a
partiucular frequency for only a short time. Also some of these devices
are polite and will not transmit in the blind so another modem must be
communicating with it. All this being said, you were really asking about
wiring up a coax cable to the module.

Soldering a small coaxial cable should be OK if you can get to ground
and antenna with very short connections. Keep in mind the loss of the
cable will be significant at 900MHz.

Ed Vogel wrote:

Hi,
I have 20 900MHZ ISM band modules and I would like to measure RF
power. I have a a Tektronix 2712 Spectrum Analyzer and some
attenuators(BNC) and RG 58 coax. Unfortunately I do not have an SMA
connection on the antenna port. there are pads for the antenna that I
could fit an SMA to but I none of the ones I can find fit quite right
because of physical interference with the RF shield.

I tried soldering the RG 58 coax to the signal and ground pads but the
signal was not visible at the spectrum analyzer. I know RG 58 is lossy
but the Belden Coax calculator said I should lose about 20% of the
power at 1 mwatt.

Any thoughts or suggestions regarding coupling this signal (100 to
500mW) to a power measurement would be greatly appreciated.

Thanks,
Ed V.



--
Joe Leikhim K4SAT
"The RFI-EMI-GUY"

The Lost Deep Thoughts By: Jack Handey
Before a mad scientist goes mad, there's probably a time
when he's only partially mad. And this is the time when he's
going to throw his best parties.