Hi Art,
Check if the results are repeatable. What happens if you exercise the attenuator? Do you get the same results every time?
As John says, it could be the driver circuit for the attenuator, but it could also be a problem in the attenuator itself. The driver circuits are on the A12 assembly.
There are two different attenuator designs. The old one is electromechanical, the new one has some built-in control logic.
Note that the attenuator needs to work in the "pad" and "through" position. For example, if the "through" position for the 10 dB section doesn't work, it may give you 7.7dB of loss due to a bad contact, but 10 dB in the "pad" position. The 20 dB section might be stuck in the "through" mode all the time. There are several possible combinations of what could be wrong. You will probably have to dig in now and check the A12 circuits.
If the problem is the attenuator, Can I do anything by myself of
I have to send the S.A. to the service ?
Attenuator repair requires some mechanical aptitude, manual dexterity, and the ability to understand how the design works. If you feel uncertain, you may be better off sending the attenuator to Agilent for repair or for an exchange unit. If the problem is on A12, you should be able to fix it.
Vladan
--- In hp_agilent_equipment@..., "John Miles" <jmiles@...> wrote:
Sounds like the driver for the 20 dB pad is stuck on, although I'm not sure
how that accounts for the -7.7 dBm business (Why isn't it -10? Attenuators
don't fail in a way that yields +2.3 dB of unexpected gain.)
Lothar B. just posted some photos of attenuator disassembly a few days ago,
but you definitely want to check the driver signals first.
-- john, KE5FX
-----Original Message-----
From: hp_agilent_equipment@...
[mailto:hp_agilent_equipment@...]On Behalf Of ik7jwy
Sent: Monday, September 28, 2009 3:19 AM
To: hp_agilent_equipment@...
Subject: [hp_agilent_equipment] Re: HP8568B Error Correction Routine
failure
--- In hp_agilent_equipment@..., "pianovt"
<pianovt@> wrote:
It could be either. There is a good way to check. Set up the
analyzer like John said to view the calibrator. Then, use the
"shift-q" (that's a small "q") function which will disable the IF
step gain switching.
Now push the "atten" key and step the attenuation up, 10 dB at
a time. (20,30, etc.) Every time you do that, the calibrator
peak should drop by 10 dB. If the drop is significantly different
from 10dB, the problem is with the attenuator.
Vladan
I did it.
This is what I see disabling the IF step switching:
ATTEN 10dB --> peak at -10,7 dBm 10
ATTEN 20dB --> peak at - 7,7 dBm 20
ATTEN 30dB --> peak at - 7,7 dBm 10+20
ATTEN 40dB --> peak at -30,9 dBm 40
ATTEN 50dB --> peak at -40,8 dBm 10+40
ATTEN 60dB --> peak at -30,9 dBm 20+40
ATTEN 70dB --> peak at -40,8 dBm 10+20+40
If the problem is the attenuator, Can I do anything by myself of
I have to send the S.A. to the service ?
Thanks
73 Art IK7JWY
