Re: QCX and peaking BPF

Alan de G1FXB

Anybody effected,
see if this helps?

I suspect Han's has being sidetracked to have rewritten that section into the build manuals so far.
(Listen to any subsequent advice provided.)

Either now by default, or if experiencing difficulty in obtaining a good peak. Utilise a 50 Ohm termination to the Antenna input and retry?
Expect the peak value to be lower than being unterminated, but it should peak?

Examples of expected signal amplitudes are given on the trouble shooting web page.
Other things to suspect are:-
Bare in mind the warning in the build manual, C1 Trimmer polythene dielectric is easily damaged by excess heat during assembly.
The build manual describes you may observe more than one increase in the BPF response, but only one should have true peak.
One QCX 20 builder had Low BPF peak / sensitivity & Low TX power out and found the common cause was an excessive loss through the shared LPF section.
Incorrect  insertion / damaged / defective components away from the the BPF, can also give rise to low peak values, as proven by other builds documented.


On 03/04/2018 01:26, Steve via Groups.Io wrote:
Just to be clear, you want to disconnect the dummy load or antenna during alignment. Otherwise the peak BPF reading will be low. 


Steve N4IAG

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