[Amps] Efficiency changes with band

[Tony Brock-Fisher]

I have an AL-1200, which puts out varying amounts of RF, with varying efficiencies across the bands. I have also noticed this on mu LK-500ZB.

Here's what the AL-1200 does:

Drive is probably 105 watts.

 

CW Power out max in SSB position:

 

Band   Po                   Ip         Ig         Pi        Ef        HV                   Comments

160     1300               740     210     2390   54        3230               1912kHz (<Bird range)

80        1520               760     240     2470   61.5    3250               3792

40        1450               740     220     2368   61.2    3200               7072

20        1320               710     205     2293   57.5    3230               14152 (even across band)

15        1450               775     255     2495   58        3220               21300

10        1350               775     255     2495   54        3220               28500





And my LK500ZB does this:



      Band Freq Load Tune Po Ig Ip 
      160 1845 95 66 1000 210 940 
      80 3700 65 85 1400 225 940 
      40 7.15 55 43 1280 215 860 
      20 14.2 55 28 1200 230 870 
      15 21.3 34 17 1150 210 860 
      10 28.45 20 9 1300 250 1000 






It's not just rolling off with frequency, as both of them can do more on a higher band than their minimum. (AL-1200 does 130W more on 15 than 20; LK-500 does 150W more on 10 then 15)



What causes this variation?



-Tony, K1KP