I would say that H73, H75 and H76 are the same at 50MHz since all 3 have SWR 1.05 at 50MHz. I am not sure why the H76 is considered the "Lab Standard".
Do you have a VNA where you can check the S11 trace to see how it looks for your sensor?
I was lucky to find one standard 478A with a recent calibration table.
There are not many on eBay from this series that have a calibration table. I saw a few in US where price is more than $1k for the ones with a cal table.
I suggest to find another 478A which has a valid cal table and borrow it for a weekend to compare it with yours by using a resistive splitter like the 11667A. This will get you an initial cal table which is better than nothing until you find a cal lab to calibrate it.
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On 24/04/2025 21:35, Paul Bicknell via groups.io wrote:
OK I have ?filed in the Tegam? on line request only for them to come back asking about end user and how many I want
My response was I am the end user and only want the price for 1 unit
I have recently bought for about 450 euros a NEW old stock HP478A option H72?? 1 to 1000 MHz
but unfortunately it does not have a calibration chart on the side any suggestions welcome
It is marked as
Air force metrology and calibration program
Base Measurement Standard
Also I assume the difference between the H72 and the H75? is the H75 is selected for its lower SWR at 50 MHz
