Keep in mind that this is one case where instrument precisipn is more important than instrument accuracy.
73, Hank, W6SX On Monday, November 10, 2014, Don Wilhelm <[email protected]> wrote: > Not so easy even with a decent scope. > 50 watts will produce 141.42 volts p-p, and 55 watts will produce 148.32 > vp-p. > That is a difference on 7.1 vp-p for a 10% difference in power. > That small difference is difficult to discern on a scope at that vertical > amplitude. > Yes, a small difference in amplitude can be discerned, but to quantify it > to less than a 5% difference is difficult to measure with a 'scope. > > 73, > Don W3FPR > > On 11/10/2014 9:23 PM, Hank Garretson wrote: > >> Easy. Put a decent scope on the RF envelope. >> >> 73, >> >> Hank, W6SX >> >> >> >> On Monday, November 10, 2014, Joe Subich, W4TV <[email protected]> wrote: >> >> My K3 increases power by 10% when in Space as opposed to Mark. >>>> >>> Two things here ... 10% is abut 0.4 dB. How did you measure the power >>> difference and did you do so with an instrument with enough resolution >>> to accurately measure that difference at the power level you were using? >>> For example a Bird Wattmeter can't possibly measure with that level of >>> accuracy nor is one likely to be able to read an analog meter that >>> closely. >>> >>> I have measured my K3 on RTTY with a wattmeter traceable to NIST and >>> specified for 3% accuracy and have done so at four specific power >>> levels (25, 55, 80 and 105 Watts) to eliminate any ALC non-linearity >>> or PA compression from consideration. The specific Mark/Space power >>> levels were measured by placing the rig into transmit in FSK_D mode >>> with the FSK input closed (Mark), measuring the power output for a >>> given power setting, then opening the FSK input and noting the PO >>> (and change). >>> >>> In all cases, the difference between MARK and SPACE was less than 2% >>> (less than the meter's specified accuracy) and at two power levels (55 >>> and 80 W) the measured difference was less than 0.2W (<0.2 dB at 55W). >>> >>> These measurements were made with standard "High tones" (2125/2295 Hz) >>> and the K3 was equipped with the optional 2.8 KHz, 8 pole IF filter. >>> >>> >>> > ______________________________________________________________ > 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 > Message delivered to [email protected] > ______________________________________________________________ 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 Message delivered to [email protected]
