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I can't be certain, but I think the reason the H72 can't be used with the 431 meter type is because the H72 sensor uses a 0.1uF decoupling cap on the output of the 100R + 100R thermistors inside the

The HP 478A Thermistor Sensor Option H72 and others state only to be used with HP 432 So it sounds like the new HP 478A Thermistor Sensor. Without the option might also not be useable / compatible

I was under the impression (although possibly incorrect) that resistance and capacitance elements found in early 478A sensors were needed corrections for 431 power meters that utilized a 10 kHz bridge

The following items have been added to the Files area of the [email protected] group. * /All HP, Agilent and Keysight instruments in folders by part numbers/3000 to 3999/E3610A,

Hmmmm?? messages passing in the night (or day) It looks like you were typing message 151895 while I was typing 151896. Hopefully my info will be helpful. Philip

I think the 8757A uses an HP 1345A display module, which is used in multiple different instruments. You can isolate the display subsystem by unplugging the 26 signal flat flex cable, at either end.

This afternoon I read more of the manual. I then checked the "X-Y-Z Analog" board that drives the video - gently "banging" (tapping with a plastic rod!) the rear corner of that board suddenly but

When I fitted a ferrite bead to my early 478A I found that the VSWR curve became smoother but it degraded from about 1.068:1 at 50 MHz to about 1.075:1 with the ferrite added. This is unavoidable as

Thanks. I tried lots of ferrite types on a VNA and quite a few were OK to use but I chose one that gave at least 70R ESR across 50 MHz to several GHz that was fairly stable on a VNA when heated.

It sounds like it could be in the analog display area, the video and sweep drive to the CRT. Check the horizontal and vertical drive to the CRT during the analog portion of the sweep. With no signal

Here's a comparison showing the VSWR of an early sensor (VNA measurement of my HP 478A) against a model based on the schematic of the later sensor. You can see that the VSWR at 50 MHz should improve

It would be reasonable to try 61 mix NiZn ferrite with a 300C curie temperature, and mu of 125. ________________________________ Sent: Saturday, May 17, 2025 8:34:17 AM To:

It almost seems like the display is in a test mode. This first pic shows the 0-10V ramp of the first band sweep, the second pic shows the ramp voltage for each of the separate bands B, C, D, E, but

The reason the efficiency also suffers with a blip at about 40-60 MHz is that some of the incident RF from a 1mW reference source will end up in the 2.7R damper resistor via the resonant path to R1.

Here's the schematic of the early 478A sensor. You can see there is a 460pF capacitor C3? in series with a 2.7R damping resistor R1. I've added some extra detail to show that there is a short red

In the last few weeks, I've had my old HP 432A power meter on the bench along with its 478A thermistor sensor. I normally only use it about once a year to check the 1mW (50 MHz) reference on another

I am seeking replacements or substitutes for these caps: C10?? HP p/n 0180-1852 x2 C14?? HP p/n 0180-1888 x2 C20?? HP p/n 0180-1851 x2 I have tried a variety of cobbled together solutions and

Hi Jeremy, Nice thread on old stuf I hardly ever use. But now I got encouraged to do some tests as well. You certainly discovered that Appendix II of the O/S Manual of the HP432A gives instructions to

Hi folks, I have converted my HP83711B signal generator into an HP83712B and have added options. See here how I did it:

Hi all, I have a HP8757A scalar network analyzer with a display problem which has appeared after some 6 months of no use. It was previously working just fine, with a HP8350B sweep generator and the