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Re: 8560E Second Converter

 

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Hello in 90% cases of that failure your U501 in A15 is dead. It is a 18-19dBm MMIC . Not critical use ERA5 or MSA0586 etc.
also if your 300Mhz Cal output is bad it that failure. They look ok still if measuring current arount it but it looses amplification. It will not tripple the 100Mhz to 300 and then not double to the 600Mhz.
best regards Peter OZ1LPR
Fra: [email protected] <[email protected]> p? vegne af Dave Ireland <mirrors@...>
Sendt: 10. februar 2022 08:00
Til: [email protected] <[email protected]>
Emne: Re: [HP-Agilent-Keysight-equipment] 8560E Second Converter
?
Askild

I have a sig gen and a specan that both go to 3GHz.

The test point on the converter is labelled LO test and I assume that this is the 600MHZ but I see nothing on this even though the 600MHz input is correct. If however it is the 3.9Ghz, then I have no way of seeing this without mixing it to another frequency.

I can't see the output of the A8 Low Band mixer as it is again too high for my specan but the RF input is correct according to the manual at -21dBm and the drive voltages are -4.96V for the -5V rail and -4.14V for the -4V rail.

The 310.75MHz output of the converter when measured as per the manual is -59dBm where it should be -38dBm.? When I measure the voltage between the test connector J19 pins 15 and 6, the drive to the converter pin switch, I get +14.48V which is in the range of the manual.

The next item in the manual is measuring the mixer bias on the test connector J19 pin 1 where I get -39mV which is outside the required range of -150mV and -800mV. After that it just says if outside the range, probably the second converter is faulty.

The voltages to the second converter are:-

J12-1 Mixer Bias:??? ??? ??? ??? ??? ??? -39mV
J12-2 +5VF:?? ??? ???? ?? ?? ???? ??? ??? ??? 4.87V
J12-3 Analogue Gnd: ??? ??? ??? ??? ??? Yes
J12-4 +10VR:?? ??? ??? ?? ??? ??? ??? ??? ??? ? 9.9V
J12-5 Pin Switch:??? ??? ??? ??? ??? ??? 14.48V
J12-7 Drain Current Sense: ??? ??? 4.86V
J12-8 Drain Voltage:??? ??? ??? ?? ?? ?? 4.85V
J12-9 Doubler Bias:??? ??? ??? ??? ??? 14.48V
J12-10 Driver Bias:??? ?? ?? ??? ??? ?? 0.465V

Without the circuit of the converter I don't know the relevance of these but the only one that looks a bit strange is the doubler bias.

Do you have any thoughts after your experience?

I will pull it apart again and check out some of yours and Gerald's suggestions on the DC feeds, the feed throughs and where this LO test point comes from.

Thanks

Dave



On 8/02/2022 5:38 pm, Askild wrote:

Hi Dave,

I once fixed a 5086-7812? second converter with a 5021-8661 board.
The only problem on this, was cracked solder joints on the feed through capacitors on the board. So I did not have to open the cavity part of the converter.
HP had cut the legs after soldering, all the way down in the solder joint. This is a bad thing as it adds stress to the solder. I was sure HP would have known better.
I have pictures of it, but not at hand right now.

Do you have a second spectrum analyzer? You should check the output of the test port on the converter.
And also the input level of the LO and IF.

Maybe you can tell us a bit more about the fault. What is the loss through the converter?
Guess this SA only go to 2.9GHz? so there is no high band?
What test equipment do you have to test and fault find with.

Regards,
Askild



On Tue, Feb 8, 2022 at 6:20 AM Dave Ireland <mirrors@...> wrote:
Sorry I rushed that last email.

For more relevance the second converter I am talking about is a 5086-7957 and it is low on gain.

Dave

On 8/02/2022 1:10 pm, Dave Ireland wrote:
Has anyone had any joy repairing on of these.

Dave



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