[Elecraft] Wattmeter for K3s Calibration

[Clay Autery]

Not referring to the XMTR Gain cal...  talking about the Tune PWR cals... 

I have a decent dummy load I think...  It's a Navy DA-412/U (50-Ohm,
600W continuous, 900 W for 15 minutes).  It has no measurable reactance
0-30 MHz, and less than 2 Ohm up to 400MHz...  at least according to the
analyzer I had access to.
Will likely get a precision 50-Ohm dummy load for cal purposes since it
only needs to be 5 and 50 W for the cals...

I'm a bit OCD on certain things...  like eliminating variables on basic
cals so I don't have to worry about my end during ops.


______________________
Clay Autery, KG5LKV
MONTAC Enterprises
(318) 518-1389

On 4/26/2016 9:57 PM, Ron D'Eau Claire wrote:
> For the Transmitter Gain calibration, all you need is a decent dummy load.
> The LP-100A is not a dummy load. My 20-year old inexpensive MFJ dummy load
> does a good job for that. (But note it has never been abused, such as
> running power into it until it gets hot or smells.) A well designed dummy
> load will have very little reactance from stray capacitance or inductance.
> That leaves only the value of the resistive element, which you can check
> with your DMM. It's the resistive element that is most susceptible to damage
> from overheating it, just like any other resistor.  
>
> For calibrating the wattmeter in your K3S beyond the factory setting,
> whatever makes you happy is perfect. There is no operational or performance
> advantage to "improving" the factory settings. The LP-100A claims 3% power
> display accuracy which is much better than most (if the claims are true).
> For example, the ARRL lab is quoted in their manual saying "They specify
> their measurement error for power as +/- 5%, and for PEP power, +/- 8%."
> Note the +/- meaning the power error may vary by 10% for constant carrier
> and 16% PEP. Those are much more typical values for good, even lab quality
> power measurement equipment.   
>
> 73, Ron AC7AC 
>
> -----Original Message-----
> From: Elecraft [mailto:elecraft-bounces at mailman.qth.net] On Behalf Of Clay
> Autery
> Sent: Tuesday, April 26, 2016 6:50 PM
> To: Elecraft Reflector
> Subject: [Elecraft] Wattmeter for K3s Calibration
>
> Would the LP-100A meet the accuracy/precision requirements to do the power
> cals outlined in the K3s Manual?
>
> If not, please supply recommendation for one that will do the job
> adequately.
>
> Thanks!
>
> --
> ______________________
> Clay Autery, KG5LKV
> MONTAC Enterprises
> (318) 518-1389
>
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