RadioBanter - Telonic VSWr kit "Rho_tector"

In message , David
writes
Hi,

I have a Telonic VSWR kit (Model TRB-2) tha is supposed to be good to
2.5GHz. It has 0.5W rating stamped on it , Z1, Z2 , RF in and Detector
out.

It came wikth 1:1 and 2 x 2:1 Precision terminators.

I would like to measure VSWR of antennae at 915 MHz using a RF Sig.
Gen, the VSWR kit and a scope. I have a 1GHz spc analyzer also if
required.

1. Can I drive this properly with the +13dBm max. from the Sig. Gen and
get reasonable results ?

2. If so, what would be a good setup and test method.

Thanks in advance for any help.

Regards

David

The Rhotector which I know is a Wheatstone bridge. It has a built-in
detector. The output is DC. You don't need a spectrum analyser. You can
use a multimeter. I used it with a sweep generator which had a maximum
output of about 56dBmV (about 8dBm).

The easiest way of using it is to insert a switched attenuator between
the generator and the RF input port. Connect the 1:1 load to Z1 or Z2
(the 'reference' port), and a 2:1 to the other (the 'unknown' port).
This represents an RLR of 10dB.
Set as much attenuation in which is consistent with getting a sensible
level of DC out (say, 20dB). Note the reading.

Remove the 2:1 load, and connect the antenna. Re-set the attenuator to
give the same DC reading. Note the attenuator setting.

The RLR of the antenna is simply 10dB + or - the difference in the
attenuator readings.

There is a small amount of error because the loading on the generator is
affected by the load on the 'unknown' port (unless the generator has
zero output impedance, which it won't have). There ways of reducing
this, but it isn't worth it. Your answer will be good enough for most
purposes.

I'll send a diagram if you need one.

Cheers,
Ian.
--