Foreword

If you are interested in doing some more advanced maintenance or repair, it’s vital to get some instruments. You don’t have to buy them at one occasion, and most people will not have money enough, but here are some ideas and hints about instruments. Some instruments can also be built and if you are careful and build it just as described you will have a nice instrument working from the first time without any calibration.

HP432A

The HP432A is a power-meter. The dynamic range is according to the front panel about –30 to +10dBm. The instrument could be very unstable so one can only use about –20 to +10 dBm, but higher levels could of course be measured with some type of attenuator or coupler.
The instrument is very sensitive and mount resistance control should not be set in a wrong position. To fix this I have put a M2,5 screw locking the control in the right position.

Bird instruments

Bird instruments manufacture high power meters and here is some hints to modify your Bird43. If you are interested to do more accurate measurements you should get a good calibrated coupler instead. Together with a mW-meter better measurements will be made.

2m extreme coupler!

When I got my hands on this coupler I just had to have one on the wall in my shack!

Oltronix powersupply

Here are some hints for maintenance of a power supply for the lab. The type shown is Oltronix B703DPM, but much of the information and many ideas are also relevant for many other types!