From df04f120a103976631047b08a35c310abfb7f604 Mon Sep 17 00:00:00 2001 From: "Matthias P. Braendli" Date: Fri, 5 Mar 2021 21:22:57 +0100 Subject: Some updates to improve PTT clicking --- README.md | 17 +++++++++++++++-- 1 file changed, 15 insertions(+), 2 deletions(-) (limited to 'README.md') diff --git a/README.md b/README.md index bf30d8d..e2dc30b 100644 --- a/README.md +++ b/README.md @@ -34,6 +34,12 @@ very first trial. Later, the external bandpass and 2x SPF5189Z were replaced by an internal bandpass with less insertion loss and a single SPF5189Z. + +*First 3cm QSO done with Picardy 2020 as IF transceiver on 2020-02-21* + +Using a Downeast Microwave 10368CK transverter. + + TODO ==== @@ -47,7 +53,7 @@ Open questions * Not tested, but plan B done (J306) * Use an additional PWM output for plan B? * Put sidetone volume setting before RV303? - * Hook up to LM375 BYPASS? + * Hook up to LM386 BYPASS? Issues ====== @@ -65,7 +71,14 @@ Issues * Unintended effect: removes LCD backlight * C319 and C326 are redundant * BC856W wrong footprint -* R327 upsets DC offset of audio amp, capacitive decoupling needed +* R327 upsets DC offset of audio amp, added 2.2uF capacitive decoupling in series with 1k + * PTT makes loud click, assemble with 100nF only, still loud + * Connected LM386 back to 8V, through 0 Ohm instead of 10 Ohm (was on 12V through 10 Ohm because DCDC noise). Still + loud. + * Investigate other muting schemes. + * Connecting BYPASS to GND generates click + * 2N3819 based muting according to G3YCC works better. + * Assemble 1k + 100nF for coupling, revert to 12k for R329, use 20k for R326 to slow down the transition a bit * 2m LPF from LimeRFE use values I don't stash * 20pF done with 2x 10pF * SW: ADC input for buttons looks messed up... -- cgit v1.2.3