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.

There was discussion of "Tuning clicks" before. My Raduino had this and also the jitter on the last digit. I would describe it as a rustling noise rather than clicking. I tried caps around the 7805 regulator but the noise was still there. What made the noise inaudible was a series 10ohm and a 2200uF electrolytic to ground in the supply to the Raduino. (Values as available in my spares box.) Small 104 caps had no effect. It is a power supply problem. The DDS takes 78ma, as much as the rest of the receiver. Presumably when the DDS frequency changes, there are several milliseconds of much higher power demand.

Like Mark, I think my bandpass filter might be off frequency. The rx seems much more sensitive at 7.5MHz than at 7.0. Next step is to test the tx side and I can more easily then plot the bandpass filter response.

Did you enable the analog vfo by adding L4?

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

I use 8 ohm earphones.? Great sounds.

I assume this tone is only present during receive.

Do you receive amateur signals when an antenna is attached? ?

How does the volume of this tone compare with the volume of received signals?

Can you describe the tone? ?Is it a steady dc note? ?What frequency?

Can you do things that cause the volume or frequency of this tone to change?

Does it change in volume when you turn down the volume control? ?(If not. problem is in the LM386)

Does it change in frequency as you tune the radio?

Does it change in frequency when you poke your finger around C102 in the BFO?

I suggest you work you way back through the receiver, shorting the signal to ground at each stage with a piece of wire to determine where the tone is coming from. ?Do you still have the tone when you short the top of C107 to ground? ?R37? ? Crystal side of C31? ?Crystal side of C23? ? Mixer side of C21? ?Mixer side of C13? ?Filter side of C11? ?The antenna? ??

I'm pretty sure it's ok to short those particular nodes to ground, but not my responsibility if you destroy something. ?You should look the schematics over hard, make sure you are probing the correct point, and verify that what you are doing won't cause harm.

> ?I was approved to join this group.

That's most reassuring.

Jerry Gaffke, KE7ER

开云体育

Worth experimenting with the speaker so I found out. I have an ex-Yaesu FT290 1W 8ohm speaker sat on top of the Bitx shipping box, sounded tinny, so I sat it on top of a cardboard tube, sounds really good now. Not bad for a 2inch speaker.

Phil-G7BZD

Your choice of a speaker for your BITX40 can really make a difference to the receive audio quality. I had been using a small 2-1/4 inch speaker (you can see it to the right of the circuit board in the picture) and struggling with the poor audio quality with lots of hiss. Picked up a small 8 ohm mobile communications speaker in a 3 x 3 x 2-1/4 inch deep black metal case and hooked it up to my Bitx40. Wow! what a difference, much of the hiss is gone and since the speaker is optimized for human voice frequencies, the SSB signals I tune in really stand out. It even improves listening to CW signals. 73, AL VE3RRD

It's a great rig. I got in on the first run before the kickstarter.?

The only downside, for some people, is the requirement for a PC. There aren't any stand-alone ADC/DAC/DSP boards available that I could find. But I didn't look very deeply because I always need the computer for logging and digital modes anyway.?

Eventually I'll get around to finishing my video review.?

73,

Sent from my pocket computer

ND6T had a nice informative post about a month before: ??

Or this one: http://bitxhacks.blogspot.com/2017/01/nd6ts-suppression-of-pesky-2nd-harmonic.html?? de ND6T