[Elecraft] Calibrating the P3 Station Monitor?

[Fred Jensen]

Most any Tektronics or HP scope, even if old, will hold its calibration, 
particularly the vertical, for a long time if it has been treated well.  
I have a very old Tek 422 which I had a chance to have calibrated for 
free a couple of years ago and it was essentially within 2% or less on 
all ranges after many years.  If you have a scope, or have access to 
one, you can measure the P_P voltage across a good DL and do a little 
arithmetic.  I'd measure the DL first, my old Cantenna measured almost 
90 ohms after 25 years. [:-)  An old Bird came in at 54 ohms.

73,

Fred ["Skip"] K6DGW
Sparks NV DM09dn
Washoe County

On 7/19/2018 3:40 PM, Peter W2IRT wrote:
> I'm good with about a 10% error (on the cautious side), and since I'm a contester, I want to ensure I'm never over about 1425 Watts when I'm competing. The Alpha 4510 was supposedly calibrated to known standards as well (for $1150 new it darned well better have been). I can live with it reading a tad high. However I was hoping to sell it to help fund my upcoming KP-1500 purchase, but the TX MON doesn't seem to be the solution, which is most unfortunate. I love what it does, but the accuracy is a problem.
>
>   - pjd
>
> -----Original Message-----
> From: Don Wilhelm [mailto:donwilh at embarqmail.com]
> Sent: Thursday, July 19, 2018 6:35 PM
> To: Peter Dougherty; Elecraft at mailman.qth.net
> Subject: Re: [Elecraft] Calibrating the P3 Station Monitor?
>
> Peter,
>
> Realistic instrument errors are up to 20% - check the ARRL Product reviews.
> It just seems your Alpha meter is off in one direction and the TX
> MONitor is off in the other direction.
>
> See if you can borrow an LP100 wattmeter which has been calibrated by
> N3LP to NIST tracable standards.  That will provide you with an up to 5%
> error.  Larry is reluctant to specify the error any closer than 5%.
>
> In this age of digital displays, we have a tendency to believe that the
> display is accurate down to the last displayed digit.  More often than
> not, that is not true.
>   
>
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