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to fix this more fully: Switchable filters to replace? the 33mhz? existing one L1-4. for the 3.5- 5mhz range a low pass filter with cutoff of 6mhz for the 7- 10mhz range a low pass filter with

Jerry, The problem is the source is square and the DBM is being used for a switch. That means the output is square.? AS to CW it works better than the old pump in a tone and can be clean with the

Unfortunately, they went and outlawed spark in 1929.? ? ;-) Jerry

I use an old noise generator.? that is a very broadband signalyou can probably tailor it to the HF band73 kd5yyk

I believe Allison has found that the four transmit LPF's are adequate. It is the board routing imposed by using the minimum possible number of relays? that is allowing those harmonics to sneak

Most attempts at transmitting CW on *Bitx* variants over the last 15 years have involved? injecting an audio tone into the mike input. Ideally, the result is indeed exactly the same as any other CW

When I tested the SSB harmonic performance with a single audio tone, it looked to me like a CW carrier. I also noted that the harmonics were much lower using the full SSB path.? Is a simple solution

Ignore that last paragraph of my previous post, included below. It's garbage text.

The easydigi does have this blocking cap. .1uf Joe KD2NFC

Assuming 16dB gain in the 45mhz amp and a 45mhz signal into the D1,D2 mixer that is at least 10db down from a 7dBm CLK2 local oscillator, the 45mhz square wave coming out of the D3,D4 mixer should

Not enough coffee this morning Jerry, However, there is NO way to create a "pseudo sine wave" that will cover that frequency spread (1.8 to 30 MHz) with the current setup and Jerry's right, the only

The highest value capacitance, the better, I would use either a nonpolarized electrolytic or polyester caps for this audio application. Then a 1:1 dc- isolating audio or data transformer to get rid of

One possibility for CW transmit would be to inject a low level keyed 45mhz square wave at CLK1, the 45mhz crystal filter will turn that into a sine wave. CLK2 can remain a square wave at Transmit_Freq

What’s a good value for the blocking cap? If that’s the purpose of the one on the easydigi, it’s value is .1uf Joe KD2NFC

Discussion of the microphone input and related DC isolation has been coming up for discussion periodically ever since the first BITX design. Best approach is to look at the schematic and that of your

Jim, Clock#2 is used for CW, but the frequency is adjusted to the dial setting +/- the CW tone depending on the CWU/CWL selection. Still, it is a square wave at the HF frequencies, not so at the

You have that backwards. CLK2 goes into the mixer at D1,D2, and is at the CW operating frequency. CLK0 and CLK1 are dead in the water when transmitting CW. Class C power amps are how most CW-only

So things are actually worse when using a transformer to isolate the mic line? So things like the easy-digi etc. make things worse? this was not my experience at all. before using a transformer, i

I don't believe that will work as CLK02 is not used for CW transmit. CLK01 produces "ON FREQUENCY OF TRANSMISSION RF (square waves) for CW and that is where the harmonics need to be surpressed. There

Hello guys, VU3EDU Subhash from india here. I was wanting to mod my bitx40 to add a touchscreen display like nextion to it just like on the ubitx. I did a lot of research on it, but only was able to