Problem - Network Analyser HP8713B

[omega12]

Hello,

my Network Analyser HP8713B has problems. You can see on the picture that it has problems. I connected a 50Ohm through cable. Need some ideas to repair it. Don´t have extension boards but maybe someone can help me. Sorry for my bad english.

Thanks, Regards

Franz

[Jay_Diddy_B]

Hi,

I have an HP8714C which should be similar. Here are a couple of tests to get you started. The idea is to measure the amplitude of the RF source.

First I set the Sweep to CW and the Freq to 10 MHz:



I then set the level to -20dBm:



I can measure the output on a Spectrum analyzer, set for a centre frequency of 10MHz and 5 MHz SPAN:



Or measured on a scope. The scope input has been set to 50 Ohms:




I get 61mV p-p. (It should be 63.6mV)


Try this test to see if the source is working.

Regards,

Jay_Diddy_B

[omega12]

Hello Jay_Diddy_B,

thanks for your answer. I made the test and it´s look like the source is ok. See the pic please. CW is at -10 dbm by 10 MHz. I don´t know if its normaly but something sweeps slightly at CW from left to the right but i think this is normaly. If i chose sweep 5 MHz than i can see a beautifull sweep on the spectrum analyser. Hm, next step?

Thanks, Franz

[Jay_Diddy_B]

Franz,

The next step is to go to the Keysight website and download the Service Manual. Here is the link:

http://literature.cdn.keysight.com/litweb/pdf/08713-90005.pdf?id=828971

Section 5 of the manual describes the test software that is built into the analyzer.

Work through this section and see if the analyzer gives any error codes.

Regards,

Jay_Diddy_B

[omega12]

Hello,

so, i found the problem. The detector diodes are toasted and i wanna also replace the protection diodes. It´s not easy to find original replaces but i hope someone have a good idea

I need 4 x detector diodes HP part number 1900-0293. This are Schottky signal diodes SMT.
I also need 4 x protection diodes HP part number 1900-0273. This are Pin Diodes.

Hm, not an easy job.

Regards, Franz

[omega12]

Hello,

i found the problem. It was U1 on the A4 Board. After replacing U1 the analyzer is working very fine.

Regards,

Franz