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Will work fine if you move the BFO a khz over into the crystal filter passband.? Trivial if the BFO is driven from a second channel of the Si5351, and gives us a better option for USB/LSB switching as well.? If you insist on analog, perhaps a varactor diode in the BFO as used on the analog vfo.

See post?/g/BITX20/message/20933

Still no Bitx40 here though.

On Mon, Feb 20, 2017 at 06:59 am, Roy Appleton wrote:

So that means that unbalancing the mixer will never be a legitimate way to introduce a carrier for tuning purposes?

? On Feb 19, 2017 10:37 PM, "Ashhar Farhan" <farhanbox@...> wrote:

The center tap that takes the audio from the mic. A caveat though, the carrier is on the skirt rather than in the center of the filter.

?

The center tap that takes the audio from the mic. A caveat though, the carrier is on the skirt rather than in the center of the filter.

- f

On 20 Feb 2017 7:58 a.m., "Ken" <chase8043@...> wrote:

4.7K resistor from center tap of R106 to 12 volts?

73

Ken VA3ABN

On Sun, Feb 19, 2017 at 8:40 AM, Ashhar Farhan <farhanbox@...> wrote:

You can inject a few millamps into the modulator at the center tap.

- f

On 19 Feb 2017 7:09 p.m., "Ken" <chase8043@...> wrote:

How do I go about unbalancing the mixer to produce a carrier?

I know that R106 balances the mixer for no carrier. So I assume a small value resistor to unbalance it.

73

Ken VA3ABN

Good morning Jerry and the group,

Had to stop last night, having probed for nearly 10 hours. Jerry, my trouble shooting is hampered by not having an up-to-date schematic. My board is a Bitx40 V3. It's interesting to note that when I power the '40 up the tone is immediate and the rcvr comes on about a second later. I have all the components taken out of the '40 except the volume control... still the tone. I wonder if India could replace the board given the amount of time spent trying to get it working? I'll continue to trouble shoot today and will keep you and the group updated. BTW, the tone encountered is not a clicking noise.

73,

Chuck K3VPZ

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From: "Jerry Gaffke via Groups.Io" <jgaffke=[email protected]>
To: [email protected]
Sent: Sunday, February 19, 2017 4:59:53 PM
Subject: Re: [BITX20] Need help with constant tone in audio output

Did you enable the analog vfo by adding L4?

If the tone is still there with no vfo, that's a hint

On Sun, Feb 19, 2017 at 01:07 pm, <chucke2@...> wrote:

Have disconnected the Raduino, tone still there.

?

Update: Mine still does that quiet clicking thing. It's just less prominent now. And still jittery on last digit, like I said.?

And I wanted to check the current draw of the PA with the 20V supply. I found that R136 doesn't do much at 20V. When I experimented with R136 at 12V it made all the difference in the world. But the no audio current draw was 90mA and long aahhh current draw was as much as 1.3 Amps. Just something about that note in my voice makes it peak high, and normal talking is around 750mA. So, current draw is about the same, going from 12V to near max of 24V. No need to recalibrate after doing it at 12V.

I don't think I could put up with the freq jumping around like that, should have a bit of hysterisis in raduino code.? So you have to reverse direction 2 or 3 clicks before anything happens.? Somebody in a recent post found that putting the supplied 0.1uf cap on the raduino pins instead of at the tuning pot on the other end of the wires made it behave somewhat better.? I might eventually go to the shuttle tuning scheme described by Don Cantrell here: ?

On Sat, Feb 18, 2017 at 06:07 pm, John Smith wrote:

Mine did this too. When the frequency readout is flicking back and forth there is a corresponding click. When the readout is not flicking a quieter clicking sound can still be heard until I keep fiddling with the knob to get the freq steady, then it's all quiet. It's like the clock generator is changing frequency in small enough amounts that it doesn't change the display. But then after changing the tuning poteniometer for a smaller one with a knurled shaft, it doesn't do that anymore. The freq still flicks back and forth like it did before, but no more quiet clicking. I just did this for a more convenient knob choice.? I also noticed before, that when it does that quiet clicking, my transmitted signal would also waver back and forth in freq while I monitored with a receiver.

?