Re: D4D: Modification for better IMD


Adam Rong
 

Folks,

For the modification 2 in the full manual, you can try a better solution. Cut a PCB trace and add a 1N4148 diode as the following picture. It will improve the carrier leakage by about 10dB. So far I haven’t seen any significant side effect. This modification is suggested by BH4DCL.

Thanks,
Adam

在 2019年5月25日,下午10:56,Adam Rong via Groups.Io <rongxh@...> 写道:

Folks,

Please refer to the photo to make modification to improve IMD. The RF output will be impacted but it is worthwhile to do so. Replace C5 by 103. Remove C6. Add a 1uF-10uF cap. Add a resistor of 22-27 ohm. Make connection as follows. Connect the positive pin of 1uF to the upper pad of C6. Connect the negative pin to the interconnection of 22-27 ohm and the original 330 ohm. Remember to adjust the audio output to just stably trigger the relay.



Thanks,
Adam



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