Re: D4D mods

Steven Weber #2802 开云体育 I would remove the diode in series with the 5V to the SA602. The minimum operating voltage for the SA602 is 4.5V and performance degrades quickly below 4.5V. ? ? Thank you, Steve. Your diode mod is effective. In my test, the carrier leakage improved by about 5 dB, as a side?effect, both USB and LSB signals increased about 1 dB which is a surprise to me. I also applied the BH4DCL diode mod, and it improved the carrier leakage further for another 3 dB, and there was no noticeable difference on the USB and LSB signal level. I did try to change the emitter resistor from 1.5k to half and it won't help too much, so I will not change it. So, my recommendation is that we apply both diode mods, hihi. ? Thanks, Adam ? toggle quoted message Show quoted text On Wed, Jul 31, 2019 at 4:36 AM Steven Weber <steve.kd1jv@...> wrote: Yes, Q1’s collector should stay above 5V when 12_V is applied. Steve ? ? From: Adam Rong Sent: Tuesday, July 30, 2019 10:33 AM To: [email protected] Subject: Re: [crkits] D4D mod ? Hi Steve, Thanks for your sharing. I will test them. One thing to confirm: If we add a diode between +5V and the collector of Q1, when 12V_R is present, the diode will be reverse biased? If not, I suppose it will mute the audio output. Thanks, Adam ? -- Thanks, Adam Rong ? 477D66F11AFA40AD9D8279F1B496FE20.png

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