MAAS or Avair RX-40 SWR/Power meter

 

Avair RX-40 Cross-needle SWR/Power meter

144 – 470MHz
Impedance 50 Ohms
Power switchable 0-15/0-150 watts
Measures forward / reflected power + VSWR
Sensitivity 3W for full scale deflection
Accuracy 10% at full scale
Connector: SO-239 (50 ohm)
Back light: 12V DC power supply (cable included)
Dimensions WxHxD in mm: 85 x 87 x 95
Weight 280g

 

MAAS RX-40 cross-needle SWR/Power meter

140-525 MHz
Impedance 50 Ohms
Power switchable 0-15/0-150 watts
Measures forward / reflected power + VSWR
Minimum required power 1W
Accuracy 10% at full scale
Connector: N-female (50 ohm)
Back light: 12V DC power supply (cable included)
Dimensions WxHxD in mm : 85 x 87 x 95
Weight 280g

 

What’s the difference?

I’ve owned an Avair AV-200 SWR meter for a number of years and been very happy with it as it covers 160m thro’ 2m. Not having any SWR metering for 70cm had been an ongoing concern despite on the face of it my 70cm scenario appearing fine with RG-213 into a Diamond Co-liner for 2m/70cm as you can’t be absolutely sure everything is well by just visual and DC checks of course.

I decided to buy a Avair RX-40 cross-needle SWR/Power meter on eBay. What actually turned up was a MAAS RX-40 cross-needle SWR/Power meter with N-type connectors!

For a moment I groaned inside and thought of having to go through the eBay resolution centre. However, the meters are pretty much clones and I suspect manufactured in the same factory. They appear identical with the exception of the RF connectors; the Avair comes with SO-239 sockets (M-type) whereas the MAAS comes with N-type sockets and has a wider RF frequency range.

Ok so the Avair’s sockets are generally more convenient in the shack but then again the ubiquitous PL-259 has significant insertion losses at 70cm with the two sockets together losing something like 2dB as against 0.2dB for N-Type on the MAAS version.  I suspect the sockets are the only difference between the two and that alone gives the MAAS RX-40 the edge if you move to N-type connectors.

I currently have the quite awful number of 6 PL-259/SO-239 connectors between the rig and the antenna so on 70cm that’s about 6dB loss…1 s-point loss and that’s before I count any loss in the RS-213 coax!