Re: RD16HHF1 power curve flattening...some
even with the mods. the TX string shows a 3 dB drop in output power...
Please exchange the two single chokes L8 / L9 with a bifilar wound coil on a e.g. FT43-50 core, see the reasons for that mod in the description already cited in this forum "ludens.cl".
BTW: how was the output power determined?
How does the power curve PIn - POut look like,
Is the output power measured at the 1 dB compresion point?
Tests on my tries to build a PA with the RD16HFF1´s using
different output transformer configurations (even with a 1:4
guanella transformer with 25 ohm coaxial cable on two BN43-202
cores + Balun with 50 ohm coaxial cable on a FT43-80 torroid core
+ bifilar choke (FT43-50 torroid) + extra choke on the center tap
with a R-C combinaiton to terminate even harmonics) I was not able
to get more than 10 W output power at P1dB. Therefore I am really
sceptical about the high power results of > 16 W.
The "hot" cores show that something must be wrong!
Did You measure the suppression of the even harmonics which
should be well suppressed (at least 40 dB) ? How good are the odd
harmoncis suppressed? If the third harmonic is only 10 dB down
(1/3 of the amplitude of the fundamental wave) the PA produces
square waves, which is not a performance of a linear amp.
Am 21.03.2018 um 12:41 schrieb John: