On 9/1/22 23:45, Bruce wrote:
I currently use HP 438 power meters and am considering upgrading.? Main driver fo upgrade is I'm getting sick of having to enter the cal factor for each frequency measurement.? I would like the replacement to be a dual channel device.
I know that latter versions of HP power meters permit entering correction tables for use with the 848X power sensors.? What would the group recommend?
Some relevant questions:
1) How hard is it to tell the PM what frequency entry to use?
2) Do any of the PMs accept an analog voltage to determine the frequency correction (that would really be fun)
3) Any known problems to look out for
The E4417/E4418 power meters have come down in price, and are very nice. They will also use the later series of sensor heads that store the calibration factors in an EEPROM in the head, which are read out by the meter and applied. You can also use the more common 84xx heads that only have the calibration factors printed on them, not stored within them, and you enter the table manually into the meter's NVRAM. Then you select the measurement frequency and it will apply the calibration factor automatically, with interpolation.
The 437B cannot read the calibration factor table from the newer sensor heads, but you can enter the table via the front panel or GPIB. It can store ten tables for ten different sensors.
My main bench instrument now is an E4417A, which I really like. The display is excellent; in some modes it will display LARGE digits which you can read across a room.
For years I used a 437B, which I still have and use occasionally in another area. Everyone complains about the display, I don't have a problem with it myself, I just don't try to use it in the dark. The design shares many attributes (and possibly components) with the 5384/5385 frequency counters, 3468/3478 DMMs, etc, so if you have one of those, you know what the display is like.
I've not looked it up, but I'm willing to bet the 437B was designed well after the 438A. While I think the 438A is a fine design in nearly all respects, everything about it seems older than the 437B. Older display and button styles, less-featureful firmware (lack of sensor calibration table storage and interpolation) etc.
I've never seen a feature by which an analog input voltage can set the correction factor.
I have every model of HP RF power meter, including the VXI and MSS models. If you'd like specific info on behaviors/features/etc on any of them that aren't covered by the documentation, don't hesitate to ask.
-Dave
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Dave McGuire, AK4HZ
New Kensington, PA
Dave McGuire