Hi all

Sorry if this has been asked and answered, but I couldn't find anything specific.

I wired the side tone as per Allard's diagram. When using headphones, things sound really good, however, when switching to the speaker, the side tone becomes almost inaudible. It's there...but too low to be useable. Also, the speaker volume is down quite a bit due to the 47 ohm resistor...again, no problem when using headphones. I'm trying to be careful, and not do anything which would damage the lm386 or the raduino. Ideas anyone?

I wasn't happy with how it made the receive sound, so I remove the modification and am using the side tone from the keyer now. I'm wondering if a person could add a second speaker???

Yes, a second speaker works, except the you lose the side tone in the headphones. Not sure what I will do. I have a little lm386 module from kits and parts. I may try setting it up as a mixer, injecting both the rx audio and the sidetone, and using pots to set the balance.....or maybe just a second speaker

How about perma-power U1? Lift R111, 1N400x to U1.4 from +12, pad and mix to Vol. pot. Tx and Rx audio separate themselves by power at K1. I've got that in play and, like an advert here in NZ, "Nobody die".

FWIW, don't bother to try to inject the sidetone at the input to the BITX audio amp (LM386). If look closely at the schematic you will see that the supply voltage to?
the LM386 gets yanked by a relay during TX so if you inject sidetone before the amp you hear a bit the sidetone and then nothing.?
This probably explains why the current solution involves inserting the sidetone at the speaker. ?

You might have also noticed a surge in the sidetone level ? It starts out low and then gets louder. ?It is surmised that this is due to a rather large?
electrolytic cap, back at the output to the LM386, that is charging up from the sidetone signal. I found that this surging seems to be reduced
with a higher impedance load at the output to the audio amp (i.e. less of a problem on my 32 Ohm Headset than on an 8 ohm speaker).?

Cheers

Michael VE3WMB / VA2NB?

P.S. Since Rx audio and sidetone are mutually exclusive, maybe rather than mixing, there might be a solution that involves somehow switching the speaker/phones between the?Raduino generated sidetone and the output of the LM386 ??

Yes, I thought of that...perhaps a little relay tied to the ptt line.

Allard's scheme works fb when using the headphones. My problem is the low side tone level when using the speaker, probably caused be the speaker impedance being much lower than the headphones. I currently have the headphone jack wired to disconnect the speaker when plugging in the headphones. I might just take the easy way out, and use a dpdt switch the back of the rig instead, switching in Allard's resistor scheme when using headphones, and switching to a separate little PC speaker for the side tone when using the speaker. Not quite as elegant,but simple.

开云体育

Yes. I have ano lm386 module from kits and parts

For anyone having the same problem, I quickly wired up my little lm386 amp board, and it looks like it will work well. I will insert it between the headphone jack switch and the speaker. I will have to pad the input so that things are kept to a reasonable level, but the sidetone/rx audio balance in the speaker now sounds great. Next up, the little fet audio mute circuit to get rid of that annoying pop when switchingb to tx