Re: Pushing the QCX (T1 question) #qcx
Alan de G1FXB
RE: QCX PA Failures:-toggle quoted messageShow quoted text
there comes a time where you cannot protect for every eventuality?
(If you not already seen it, have a look at the PA circuitry in the NC2030 design,
I guess something similar was not included for reason of cost, both component and also PCB size increase?)
It's an example of when potentially it costs more for the protection circuit than the likely failure scenario,
In the QCX It's Q1->3, Q6 and possibly IC3, they add up to something sub $4 to replace??
(Q6 Should never fail spectacularly as often as it's being reported, it's rated at 2A dissipation.
The QCX on TX consumes circa 500mA TOTAL. Why doesn't a fuse save it?)
the failure of the si5351 is 1 in 5,500+ QCX's that have being built occurrence?
The best protection is afforded by the operator him / her self, perhaps think before pushing a QCX hard..
Remember there is no fancy SWR mismatch or over temp protection on long duty cycle modes.
"Without any protection circuits the QCX will try it's very best to fulfil it's purpose,
right up to the point of failure."
On 27/08/2018 08:38, Alan G4ZFQ wrote:
;-) I think a narrow BPF improves the performance.