#QCX 4174 Ready for practice test #qcx


The tuner has been changed, tuning display by the passive bridge circuit with LED works well.
At 15V, the following values ​​are obtained:
RX 71mA   (with 5V switching regulator, display light on 5V with about 12mA - is sufficiently bright
TX 600mA  5.5W  or  510mA  4.6W  (depending on tuner setting)
The reception reports from the RBN look real


The practice test was negative. My mistake: My tuner tunes to antenna voltage, no control of adaptation to the PA. This caused the PA to overload, causing the MPS2907 to burn. Repair ok. Change tuner is in progress.
I use follow regulator https://www.ebay.de/itm/Mini-DC-DC-4V-12-24V-To-5V-3A-Adjustable-Step-Down-Power-Module-Buck-Converter/272694825804
In my overvoltage-protection the 0,47µ - C is reduced to 10nF
There is a unknown problem on my QCX: Full QSK works fine, Semi QSK not -
no intermission between the characters (version 1.00e)


Looks very nice!  Everything in one box.

Which switching regulator did you use?  I'm about 2/3 of the way through building mine and was considering
using this one: https://power.murata.com/data/power/oki-78sr.pdf
It's supposed to fit in a 7805 foot print.

It should save significant power when running at higher voltages. I did have some noise concerns, however.
I guess the best thing to do is try it both with the 7805 and the Murata switcher and see if I can find any issues.

-Bill W2WZ



Here is my QCX with some personal adjustments (I like small personal adjustments):
Build in battery (15,8V 850mAh LiPO) with BMS
Build in antenna-tuner (i use "random antennas")
Switching Step-down-regulator instead analog regulator (reduces the power consumption at RX noticeably)
Build in touch-paddle, based on ATMEGA 48 (second function - operates as rotary encoder)
Overvoltage protection for PA (useful with battery voltage above 15V and missing load by antenna or dummy)
The enclousure is made of PCB material FR4