Joe,
Last week I tested this suggestion and it does not help much. It reduces
the pop but not much.
Next week when I am back in town I will try some other ideas and
see.
Switching the 12V on/off is causing it, including the relay which cuts
out the volume control M1 M2 points!
Raj, vu2zap
At 06/04/2017, you wrote:
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"... Power the audio stages
directly by connecting 12V line to the junction of R111, R113 and
D18.
Now you will hear your own voice during TX and we need to mute
it..."
Is that so bad - to hear your own voice during transmission??? Would
this alone reduce or eliminate the pop on keying the transmitter?
Also, this could be a nice sidetone monitor when injecting a tone into
the mic when attempting to use the BitX for CW?
I put the BitX away for awhile until I could find a solution to the
popping!?? I use earphones exclusively, no speaker, and the pop
sounds like a bolt of lightning to me.?
thanks
Joe W3TTT
On Wed, Mar 8, 2017 at 3:03 AM, Raj vu2zap
<vu2zap@...>
wrote:
- No problem Simon,
- Now its good time at Melbourne for a beer or to try another hack on
bitx40.
- Try this:
- 1. Power the audio stages directly by connecting 12V line to the
junction of R111, R113 and D18.
- Now you will hear your own voice during TX and we need to mute
it.
- 2. Take a 2N7000 or similar and connect SOURCE to ground, DRAIN to
the top of the volume control (M1/M2).
- feed the TX 12V through a 10K or nearby value to the gate.
- This should mute the amp during TX.
- If this works for you then remove the diode D18!
- Caveat: I have not tried it as I am at the coffee farm this week.
Itching to get back to my board but it will be Monday next!
- While in TX mode some RF might get into the amp stage and be just as
annoying.
- Then we have to work more on that! A 0.01 across the volume control
might fix this if it happens.
- Cheers
- Raj
Raj vu2zap