Serge, UT5JCW hat am 5. 9. 19 seine Kunden zu diesem Problem informiert. Es handelt sich um einen Fehler bei der Herstellung des PCB. Nach Absprache mit Serge, veröffentliche ich hier seine Email zur Information:
If your converter has low output of 144 MHz signal then read below.
I discovered a problem in recent 759/144 MHz converters that causes low output of 144 MHz signal.
The PCB factory did a mistake in PCB design. Both ground wings of IC3 MAR-3 are cut off of
ground. Scrabe out blue pain along both wings (see pic1) and solder them
to the ground see (pic2). It increases 2m output at about 15dB.
Sorry for a problem.
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With best regards Serge UT5JCW
73 de Wilfried OE9WLJ