[NLRS] [Mw] HP power meter

[Dr. Gerald N. Johnson]

On 1/25/2016 5:59 PM, David Weinreich wrote:
> Dr. Jerry,
>
> It's been 20 years since I supervised people at COMSAT Laboratories
> using HP 432A and 436A power meters with 8478 and 848X power sensors.
> I believe the reason for the infatuation with the 436A is its ability
> to be included in automated test setups using the HPIB or GPIB
> interface busses.

That would explain many uses. The wild thing is that the 432A has a 
plotter output that is proportional to the meter motion, so a digital 
display wouldn't be difficult, I think HP actually made one. It would 
need two ranges for the same DC range one 3 full scale and the other 10 
full scale.

And the 436 has a similar output so an analog meter would be easy to add 
for filter alignment applications.

  The other reason is that some people seem to be in
> love with that .01 dB digit. Personally, I don't believe that .01 dB
> really exist but there are those who insist that meaningful
> differences of .01 dB exist in microwave power measurements.

I'm sure those differences do exist, but I really doubt the meter will 
show them repeatably. .01 dB would probably be the difference on 
tightening the SMA ring to 4.5 or 5 inch pounds torque some days. And 
most likely with everything static and supposedly controlled by feed 
back loops the .01 dB digit probably wanders in a random pattern. Much 
like measuerments W0PFP would teach his engineering students, his quote 
was "Measure with micrometer, mark with chalk, cut with axe" his point 
was that the result of such a digital readout or 9 digits from a 
calculator from 3 digit or 2 digit input wasn't reasonable. Many a 
counter shows a 10 or 12 digit display but has an internal standard onl 
good to 7 or 8 significant digits. I have an EIP with 12 digits good to 
18 GHz that its internal standard was maybe good for 9 significant 
digits. Its now supplied with the output of an HP 10811 SC cut crystal 
standard thats probably good for 11 digits, but I've not checked its 
calibration.

  >I do
> think that the 848X power sensors were more capable than the 8478 but
> for an amateur making measurements on one transceiver, most often for
> transmitter output, or for return loss measurements for antennas or
> filters, I think the 8478 provides about the same capability, as long
> as the correct power sensor calibration and zeroing procedure is
> followed.
>
> That's my 2 cents.
>
> 73, David Weinreich WA2VUJ/8
>
>
Thank your for your 2 cents. I was feeling the same especially at the 
prices asked and gotten for claimed working 848X sensors.

73, Jerry, K0CQ