Jack, You need to put an 'exponential' symbol between those parentheses and the "2" in those formulas - the voltage must be squared where the formulas you included indicate multiplying by 2.
For your power output level, it *may* be a bit low. Check the output with a 13.8 volt supply voltage - if it does not come up close to the 4 watt level on 30 meters (highest output band), you may want to add the "Power Mod" - it is just 2 resistors to change. For those with KX1s already producing 4 watts or more on 30 meters, I do not recommend adding the power mod - see my prior responses on that subject. 73, Don W3FPR Jack Regan wrote: > This update represents a more accurate determination of the power output AND > an adjustment of the KX1 so it would reflect these new, accurate power > measurements. > > > > The DL1 was used to determine the power output. Some initial confusion > occured becasue the DL1's formula for calculating power is not correct! > > > > Many thanks to Don Wilhelm for helping sort this out! He has been > responding with detailed, accurate and elegant suggestions re: what is going > on. > > The DL1 manual formula is... > > > > P(watts)=((V(volts)x1.414)+0.15))2/50 > > > > Three things are going on here. The TP1 is connected to the 25 ohm output of > the resistor chain, the diode correction is not part of the rms correction > and the value of the diode is not as accurate as it could be. > > > > Don's formula is... > > > > P(watts)=((V(volts)+diode drop))2/25 > > > > In his note to me re: this he "left the derivation to the student" and this > is the formula I came up with. > > > > P(watts)=((V(volts)+diode drop))x 1.414))2/50 > > > > When my formula produced a result different than Don's (by a very small > positive amount) I jumped to the conclusion that Don's formula was quick and > easy ballpark technique! Wrong! > > > > The difference in our figures was that Don used the square root of two > whereas I used the "standard" approximation 1.414!!!!! > > > > I will follow Don's lead and leave the derivation to the student! If you > email me I will send you a copy of Don's math!!! Very simple and elegant! > > > > To continue... > > > > I measured my diode drop and found it to be .330mv so the formula for my DL1 > is > > P(watts)=((V(volts)+0.33))2/25 or > > P(watts)=((V(volts)+0.33))x (sq. root of 2))2/50 > > > > Taking accurate measurements and finding (as previously posted) that the KX1 > was showing too high an output I took Don's advice and redid the C9 and the > Forward Power adjustments on the KX1. > > > > After adjusting the KX1 to show the same readings as the DL1 I now have the > following baseline figures on the KX1 with 12VDC(DISP:BAT). > > > > > > FREQ TP1 VDC TP1 WATTS KX1 WATTS KX1 SWR > > 3.550 7.84 2.60 2.6 1.0 > > 7.040 7.34 2.30 2.3 1.0 > > 10.120 8.45 3.25 3.24-3.26 1.0 > > 14.050 7.03 2.19 2.20 1.0 > > > > With the new baseline the agenda has changed. > > > > 1. If in fact these outputs are significantly low then correct them thru > adjustments, not modifications. They are higher than the 9 VDC specs > but are they > far enough below the 12VDC specs to bother with. I'll do some reading > and research > and then decide. Any input or suggestions would be appreciated. > > > > 2. Explore the possibility of increasing the power output to a full 5 > watts. > Don has pointed out the fact that more than just the oscillator, final > rf > transistor and toroids are involved in putting out more than 4 watts. > Perhaps an > out board power amp using the KX1 as a VFO would be the way to go! > QST has had several > articles on power amp construction lately! > > > > 3. Understand why the Scope and the DL1 are not showing the same results. > > > > 4. Get the scope to match the DL1. > > > > Again, just for the record, the KX1 is working on all bands. > > > > Jack AE6GC > > > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[email protected] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > ------------------------------------------------------------------------ > > > No virus found in this incoming message. > Checked by AVG - www.avg.com > Version: 8.0.238 / Virus Database: 270.11.23/2016 - Release Date: 03/21/09 > 17:58:00 > > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
