开云体育

Hi All, Has anyone seen and fixed this error before I pull the case? Thanks Chris

hello everyone Bonjour a tous... This fine 80 MhZ AWG (circa 2016) needs a full calibration similar to the 33220A 20 MhZ. Do either of these generators, use a back up battery or NV ram that can lose the calibration Constants over the years? Can calibrate in a few hours? Any tips or experience (on either part number) is appreciated. Bon Soiree jon

Hello everyone. Suddenly my spectrum analyzer (HP 8566B) has the following problems: the low band signal is about 40 dB lower than it should be. The high band has stopped working: the various bands no longer appear on the screen, but a single band similar to the low band and the signal is completely absent! I strongly suspect that the YTX oscillator is dead or almost dead! Does anyone have any ideas about this? Thanks. Images: HP8566B and output at first LO connector. IMG_20250504_121626.jpg (89.93 kB, 1000x750 - viewed 13 times.) IMG_20250504_121605.jpg (122 kB, 1000x750 - viewed 16 times.)

Hi all a bit off base but has anyone ever come across a connector that is the same size and form as a BNC but it does not have the bayonet lugs and uses a locking grove where the lugs would be it is Made by Radial and there is even a High voltage version with more insulation like the high voltage BNC as I would like to get hold of a few mating sets Regards Paul located in the UK

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 power meter. However, I've spent a bit more time looking at the 478A sensor and wondered if it was worth sharing some of the knowledge gained and also some of the options for reducing the measurement uncertainty compared to using a standard sensor at 50 MHz. I've looked at the input match, the efficiency and also at how the 478A has had some changes internally over the years. One obvious option to improve the input match at 50 MHz is to buy a special version with option H75 or option H76. These are probably quite rare and expensive. Another option is to improve the input match of a standard sensor by adding a low loss (external) matching section inline with the standard sensor. I have done this and have achieved good results. I'll show the design process and test results in this thread. The standard sensor has a fairly grim spec for input VSWR at 50 MHz of about 1.3:1. However, it shouldn't be this poor at 50 MHz if you look at what is inside the sensor and model the VSWR. In theory, an older version of the 478A (like mine) should manage a VSWR of about 1.07:1 at 50 MHz. The later versions might be closer to 1.05:1 at 50 MHz. So in this sense, there probably isn't much point trying to improve the match if the aim is to measure a 1mW reference from a typical HP power meter. This is because the source VSWR of the 1mW reference is likely to be much lower than its spec of about 1.06:1. So the mismatch uncertainty should be negligible. Only a calibration house should really be concerned here, but I thought I would have a go at improving my sensor anyway. The following posts show the thought process and the modelling and the test results. I've attached a VSWR plot of the input VSWR of an early HP 478A sensor. This was taken with a lab VNA set to a really slow sweep time of about 20 seconds, although slowing the sweep time from less than 1 second to 20 seconds didn't seem to make much difference. You can see there is a kink in the VSWR at 50 MHz and this has always bugged me because it causes a bump in the efficiency across about 40-60 MHz. I've lived with this 'bump' issue ever since I first got this sensor back in the 1990s. But now I've managed to get rid of it and I'll show what causes it and how to upgrade an older sensor like mine to get rid of it. -- Regards Jeremy

Hi, I recently bought HP 8753C with no option. I would like to make a full upgrade with options 002,010 and 006. (010) I have only an 85046A test set however I would like to use swept oscillator HP 8350B so hopefully, that will not caused any issue with soft or with the test set to future. Anyway, I got the codes for HP 8753C but unfortunately, I struggling to found proper procedures on how to install these upgrades. An available method I found is only for 8753E and higher thus I would like to ask you if you can recommend where to find it or if its the same procedure as for 8753E. Thanks

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 10MHz - 20GHz plug-in. What happens is that on switch-on, it goes thru the self-test and then reverts to a display which seems to contain some correct information such as frequency span, key button names (at the right), and a 'noisy' scan waveform (as expected) - BUT the display refresh is very slow and is well off-centre - it is clearly cycling through the 4 'display channels sources' but it is nearly unreadable (certainly unusable). I have another 8757A which I use with another sweeper which works well, and by using this as a 'test reference' I can determine which buttons to the right of the screen to use to perform some tests. In this way, I have called up the test pattern display (SYSTEM -> MORE -> SERVICE -> DISPLAY -> TEST PATTERN) and this generates the wanted test pattern BUT this is also well off-centre and refreshed slowly. I have checked the error-code LEDs (removed the top cover of course) and they are all off (zero) after switch-on or after "PRESET" which indicates no error found, and also checked the +15V, -15V and +5V on the small power board with the fuses. The +105V rail there is also correct. This problem is independent of whether the 8350B sweeper is on or off, and if it is on the PRESET button initializes both the 8757 and the 8350 as it should. I have compared the problem unit with the working unit and the basic functionality would appear to be present. I am wondering if the battery on the CPU board (backing up some constants?) could be a reason, but I doubt it - I can replace this tomorrow if I think it might be. I know that the refresh frequency of the display will be lower with the more channels that are being scanned (A, B, C, R) but this does not appear to change the problem on the unit that I am dealing with. For what it's worth, I have a comprehensive workshop and lab at home and I am used to working with both microprocessor designs and (more so) with microwave / ATV designs. I have read the service manual and operating manual but with so many pages and different references I am not sure where I should be looking. Would anyone here have a good idea of where the problem could be? My sincere thanks in advance.