Re: 8594E input attenuator issue?
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Anyone can pinpoint me to the schematics of the drive board for my 33321-60036 ATT ? While waiting to find a replacement plunger, I will breadboard the necessary to electrically actuate
the solenoids. I am not familiar with HP documentation, but I heard something about looking for a CLIP. ?
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From: [email protected] <[email protected]>
On Behalf Of Nicolas Mailloux
Sent: 21 janvier 2022 06:54
To: [email protected]
Subject: Re: [HP-Agilent-Keysight-equipment] 8594E input attenuator issue?
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?Since I have a plunger/piton broken at the DC Block, I can¡¯t make measurements easily. I am getting inconsistent measurements when tje ATT is assembled.?
At this point here¡¯s what I think I should do :
Replace the broken plunger to put the ATT in mechanical order
Bench measure the ATT correctly?
Show a video of the issue if it still persists.?
Looking on ebay, I see many DC-4Ghz 70 dB ATT. The ones that are not the same exact number as mine (33321-60036) seem to only differ in their electronic driver board. They are not too expensive at around 60$. (I talk about other 33321 series
ATT)
However, for some reason, the same ATT as mine cost 5 times more, that is a bummer.?
With all the trouble shooting done to date, I think my ATT was fine and the problem is elsewhere :(
A fellow member of the group offered to send me one of his ATT to help me fix mine.?
?
?
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Hi,
Yes its correct that its not needed to have and output terminator to measure the DC resistance, but you need to calculate the resistance, as you have done.
So as you write, 61.11ohm is correct to measure between input and ground for a 10dB attenuator, when the output is not terminated.
But when a terminator is added to the output , it should then measure 50 ohm.?
Nicolas, your previous measurement of resistance between input and output, and input to ground and output to ground, all these values are correct for 10, 20 and 40 dB attenuators.
But that you did not get 50 ohm when you used an terminator on the output, you should check that the terminator measures 50 ohm, and also check that the DC-block was not active.
If this is OK, try moving the terminator to the opposite side, and measure the other way, as there might be a bad contact on one side.
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On Thu, Jan 20, 2022 at 8:42 PM Ozan <ozan_g@...> wrote:
50-ohm termination is needed to get the correct attenuation but for measuring resistances it is not needed.?
From your earlier measurements it looks like:
PAD2 is 20dB section
PAD3 is 40dB section
PAD4 is 10dB section
If we treat each section as a pi attenuator (I don't know if it is valid with these units) expected values with open termination are?
10dB section (PAD4?)
input or output to ground 61.11ohm
Across 51.95
20dB section (PAD2?)
input or output to ground 51ohm
Across 81.8ohm
40dB section (PAD3?)
input or output to ground ~50ohm
Across 98-ohm
Doesn't look like there is a gross failure.?
Next you can do a DC attenuation check. Apply 1V DC to one side of 40dB attenuator and measure the voltage at the other side while terminating to 50-ohm. Correct voltage is 10mV, from scope measurements we expect wrong value of ~ 20mV. Then swap the input and
output side and do the same.
This will tell at least at DC if the attenuation is correct.?
Ozan
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On Thu, Jan 20, 2022 at 11:21 AM, Nicolas Mailloux wrote:
Hi!
I put a 50ohm termination on the input side and measured at the output.
PAD 2 and 3 are giving 50 ohm, while PAD 4 is measuring 61.1 ohm as my previous measurements did.
?
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Remember that an attenuator must be terminated in 50 ohms to have the correct attenuation.
You could do a simple test with your DMM, with the attenuator assembled (except for the cover over the control solenoids.
Put a 50 ohm terminator on one side, and measure between center and screen on the other side.
Move the solenoids, so only one pad is active at a time, and you should measure very close to 50 ohm on this connector.
Of course with the exception of the DC-block.
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Ozan?: These measurements are from input to output.
PAD 2 : 81.69 ohm
PAD 3 : 98.04 ohm
PAD 4 : 51.65 ohm
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These are from input to ground :
PAD 2 : 51.05 ohm
PAD 3 : 49.95 ohm
PAD 4 : 60.96 Ohm
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There are from output to ground :
PAD 2 : 51.10
PAD 3 : 50.16
PAD 4 : 61.23
?
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On Thu, Jan 20, 2022 at 07:58 AM, Nicolas Mailloux wrote:
n8zmTWH@... : I do not have/searched the schematics of my particular ATT. I based my assumptions on a previous post from someone that attached schematics.
They may not be the right ones.
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My exact model number is : 33321-60036 it goes to 70dB I think. My 8594E is from 9kHz to 2.9GHz.
Measuring the pads where the contact blades touch when selected, still in the aluminum block I get these readings :
They are in order from Input to Output.
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PAD 2 : 81.69 ohm
PAD 3 : 98.04 ohm
PAD 4 : 51.65 ohm
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Both service manual and CLIP show 10dB/20dB/40dB sections.
The pads have three terminals, input/output/ground (input/output being symmetric). Ground is connected to the metal frame.? Are above resistance measurements from one pad to ground? It may or may not tell much but what resistance do you measure from each side
to ground??
Ozan
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