[Elecraft] How Accurate of 50-Ohm Dummy Load for 50 Watt TX Gain Calibration?

[Phil Hystad]

Thanks to Wayne, Tony, and Don for their answers to my question.

I am going to use my DL-1 20-watt load and do the calibration manually and monitor the heating of the resistors (actually, I have a nice Fluke temperature measurement tool to do job if needed).

73, phil, K7PEH


> On Mar 28, 2015, at 5:37 PM, Wayne Burdick <n6kr at elecraft.com> wrote:
> 
> Anything under 2:1 will allow the TX GAIN calibration to work, but I'd shot for < 1.5:1.
> 
> Wayne
> N6KR
> 
> 
> On Mar 27, 2015, at 5:27 PM, Phil Hystad <phystad at mac.com> wrote:
> 
>> I have two dummy loads that might be useful for the 50-watt TX-gain calibration but neither of them are dead on with a 1:1 SWR and 50 ohms resistive load.  Actually, my smaller 150 watt dummy load is closest with a range of 42 ohms on the load to about 55 ohms on the high end as I step through the frequency ranges of my Antenna analyzer.  My 1500-watt dummy load is worse as the resistance goes up to 87 ohms Z (resistive plus reactive) with 54 MHz test signal (using MFJ 259 analyzer).
>> 
>> My little Elecraft DL-1 20-watt dummy load (mini-module kit) is best as it is flat 50-ohms resistive across the entire HF spectrum.  I am thinking of using and following the advice of Wayne to let it cool down between bands.  But…
>> 
>> If I want to let the dummy load cool down between bands then can this be done using the automated procedure with the K3 utility or do I have to run the manual procedure.  In other words, does the automated procedure allow me to automate the process on a band by band basis.  I have not tried it yet because I didn’t want to start something until I was ready to finish it (and I have not installed the latest firmware yet).
>> 
>> Question:  How accurate should the dummy load be — is an SWR of 1.2:1 and under good enough?
>> 
>> Question:  Does the K3 Utility allow me to perform the TX gain calibration on a band by band basis?
>> 
>> Thanks.
>> 
>> 73, phil, K7PEH
>> 
>> 
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