[Test-Equipment] HP 141 analyzer low gain

[Marco Bruno]

At 19.54 28/02/2004, you wrote:
>I had a few replies off list. I will add a little more info that may help 
>diagnose the problem.
>....
>After repairing the attenuater I checked the level through the attenuater, 
>low pass filter and the additional 3 db attenuater that go just before the 
>mixer input. Levels were what they should be there. (-3.5 db) for filter 
>and 3 db attenuater. So it looks like they did not get destroyed when the 
>front end attenuater got smoked.
>
>Any other ideas appreciated.
>
>Thanks
>Gary  K4FMX

Gary and all,

to test the first mixer diodes is very simple, and does not require 
disassembing the mixer.
Simply remove the semirigid cable feeding the RF input to the mixer. Take a
multimeter with diode test function and measure the voltage drop between
the central pin of the female SMA on the mixer body and ground. You are
looking at two Schottky diodes in antiparallel, so will see about 380 mV in
both directions. If the reading is in this order (and symmetrical) the diodes
are probably good.

Be careful not to damage the SMA center with the multimeter probe.

Hope this helps...

Marco IK1ODO