I recently purchased a 2nd hand Marconi 6950 RF Power meter with a
6910 probe covering 10MHz to 20GHz.

It's OK on the 5dBm and above ranges, but at the 0dBm and below
ranges there is an increasingly large zero offset as the range
decreases further.

Is this likely to be the probe or the meter, and if so is it simply a
calibration job or is one of these bits likely to be dodgey, and
therefore I am the pround owner of a kipper?

73 Howard G6LVB

Hey Howard

hope your well.

You coming to Martlesham??

I am not familiar with that meter but there are a couple of
possibilities:

1. the head has been overloaded (prob the reason)

2. the calibration of the unit is out.

I was looking for details of a Marconi 6559 meter on the net and
found a few places with handbooks. Maybe that will help.

Its likely that the meter has been overloaded and the head is now
misalligned - I have some details in the Microwave Updates on fixing
these thermistor type heads - I will see what I can find for you.

Regards

Simon GM4PLM


--- In ukmicrowaves@y..., "Howard Long" <hlong@b...> wrote:

I recently purchased a 2nd hand Marconi 6950 RF Power meter with a
6910 probe covering 10MHz to 20GHz.

It's OK on the 5dBm and above ranges, but at the 0dBm and below
ranges there is an increasingly large zero offset as the range
decreases further.

Is this likely to be the probe or the meter, and if so is it simply

a

calibration job or is one of these bits likely to be dodgey, and
therefore I am the pround owner of a kipper?

73 Howard G6LVB

--- In ukmicrowaves@y..., "p.day" <peter@g...> wrote:

Marconi meters such as the 6460 type (mine) do tend to do this in

the low

power setting and there should be a "zero adjust" pot on the front

panel. I

always set mine up in the 30uW switch position after the unit has

warmed up

for some minutes even if I'm measuring much higher power levels.

Perfect! A 10 second fix that worked.

Thanks a lot.

73 Howard G6LVB

our first satisfied customer!

well done Peter!



--- In ukmicrowaves@y..., "Howard Long" <hlong@b...> wrote:

--- In ukmicrowaves@y..., "p.day" <peter@g...> wrote:

Marconi meters such as the 6460 type (mine) do tend to do this

in

the low

power setting and there should be a "zero adjust" pot on the

front

panel. I

always set mine up in the 30uW switch position after the unit

has

warmed up

for some minutes even if I'm measuring much higher power levels.

Perfect! A 10 second fix that worked.

Thanks a lot.

73 Howard G6LVB

I'm blushing!

Great Howard ... nice to know your pwr meter is OK..

73

Peter, G3PHO