Re: QCX 40 sn 1167 with TOO MUCH POWER OUT
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Good show John.? Sometimes we forget that the majority of builders complete their
QCX units with no problems.? We usually only see the problem cases here because
this is the place to go for help.? That sometimes gives the false impression that there
are significant problems.?
Thanks for posting a success story.? Sometimes we need that.
Arv (can't hear, partially blind, old-76, and ugly) K7HKL
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On Mon, Dec 4, 2017 at 12:33 PM, John Kirby <n3aaz_qrp_1@...> wrote:
Not too shabby for a 77 year old ham with trifocals,? one good eye, hands that shake in opposite direction and cold soldering iron about the size of a rusty nail.
Inductors T1 and L4 wound per manual
T1 mounted bottom side of pcb
C1, 30 pF variable was DOA, boneyard fixed that
T4 mounted bottom side of pcb with boneyard trimmer cap
Installed;
L5 mod
10k Q5/PA instability mod
6.8k LCD mod
Passed smoke test first try
Except for replacing C1, passed alignment procedure no sweat
Back in the day young hams were always taught 'peak the grid ... dip the plate' current. So I pEEked at my grid dip meter and dipped my head in a moment of slience before keying up the PA for the first time ... double wow WOW based on most reports read here on the list ... way too much power out. Way more than 5W out at less than 12 Volts (see image attached).
Cavaet 1 ...no LPF components installed...
I have a jumper between C27 and C28
Cavaet 2 ... this is my very first class E PA and first reason for this experiment, but, I am sure, there are between? 'umpteen and skettyeight' distorted harmonic signals contributing to this output measurment.
More to follow after OUTPUT FILTER and L4 / C30 evaluations.
Thanks again Hans for such a delightful project :>)
The articulation in your manual both construction and theory is beyond description.
72 73
John
N3AAZ
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