[Amps] About LP100A

[Roger (K8RI)]

Be careful of the scope across a known load.  Accuracy depends on the 
precision of the resistor and on many bands may require compensation.  
If you have a good dummy load, there is the calibration of the load.My 
DL5K requires compensation above 40 meters. It's great on 160, 75, and 
40, but the SWR goes up in a hurry from there.

73, Roger (K8RI)

On 6/18/2017 Sunday 9:36 PM, Jim Brown wrote:
> Hi Jim,
>
> You've pointed out the obvious problem -- man who has more than one 
> watch never knows what time it is. :)
>
> My LP100A came from the estate of an SK, with one coupler.  I sent the 
> LP100A and the coupler to Larry to cal for me, and to cal the second 
> coupler that I bought. So I know it's calibrated. For the LP100A, the 
> cables between the coupler and the unit are part of the calibration, 
> and they're labeled.
>
> Your MB-1 calibration using the scope across a known load is pretty 
> good, as good as the calibration of the scope and the load.. :)  It 
> really does come down to using the tools and instrumentation in our 
> own personal labs to get as close as practical to the fundamentals of 
> what we're measuring.
>
> 73, Jim K9YC
>
> On Sun,6/18/2017 5:28 PM, MU 4CX250B wrote:
>> I have an LP100A wattmeter and like it very much. But how do any of
>> you know how accurate it really is? The only way to know is with a
>> calibration standard, and RF power is notoriously difficult to measure
>> accurately. I've compared the LP100A to the Alpha 4510, and a
>> MeterBuilder MB-1, and by measuring the RMS RF voltage (with a
>> calibrated Tek oscilloscope) across a 50 ohm dummy load. There's no
>> obvious consistency among these wattmeters. The readings vary from one
>> another with frequency and power level, by as much as five percent. My
>> guess is that the MB-1 is likely the most accurate, based on the
>> calibration curves and methodology supplied by the manufacturer. But
>> that is still just a guess.
>
>
> _______________________________________________
> Amps mailing list
> Amps at contesting.com
> http://lists.contesting.com/mailman/listinfo/amps
>


---
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus