He has said previously that he understands that the regulator is out of regulation. The tuning clicks are due to current surges into the ATMega328P on the Nano causing drops on the radio's 12v line du

You got it, I was wrong. Q16 is the audio pre-amp. Jerry

Mad is right. Just turning down the volume is good enough for the majority of *Bitx* owners. And how designer meant for this minimalist rig was meant to be used. But if you got the gain way up to hear

If in your location you get stations you want to hear that are strong enough to still sound distorted when the volume control is turned down, then you do need the dynamic range that RF attenuation giv

Ravi, Your equations look correct, though this might be a more concise description of the math involved: https://groups.io/g/BITX20/message/44515 That was for a uBitx-v3, so had the 12mhz IF crystals,

The AGC board operates on two different signals in the radio. AGC attenuation level is determined by measuring the audio signal level after all of the filters that pick out only your signal of interes

Stephan, Driving 1khz into C31 is not going to give much response because the amplifier at Q3 is operating at 12mhz, and the 0.1uF at C33 will mostly block the 1khz audio frequency. The signals throug

Yes, on the uBitx, K1-14 is shorted to ground for DC by T2 pins 1 and 6 by way of L1,L2,L3,L4. At DC, T2,L1,L2,L3,L4 are all just a few centimeters of magnet wire, and present very little resistance.

#ubitx

Cor, I find that busting up a conversation into separate threads as the subject wanders makes it very difficult to follow. Especially months later when I search for it and find that it has bifurcated

None. It's a conversation.

Sandeep wrote: > Guys, any way can we know voltages approx across 20M traps ? > excited with 25 watt... I'll assume you have a 40m dipole, with 20m traps halfway down each leg to prevent 20m energy fr

Curious, I did see the photo in the group website. Looks like it has since been deleted. Jerry

It's very tough, to protect a radio installation from a direct lightning strike But it's well worth protecting your gear from high voltage electric fields. Just the wind blowing on an antenna wire can

If D7 failed as a dead short, you are one lucky guy. Does the Raduino work? Jerry

If you suspect D7 is shorting the supply, ok to just remove D7. It never was doing any good, there is an error in the board layout. It should be across the coil of relay K1, exactly like that other di

Unfortunately, the link to download the Bitx40 schematic as a pdf from hfsignals.com is broken. Not to point a finger, but somebody should fix this. From hfsignals.com, click "Bitx40", and then "Circu

Perfect!

I've got about 10 of the HF dvm's lying about, I do have better, but the HF are generally the first dvm I reach for. Mostly because there is likely to be one close at hand. I've never found accuracy t

The LM2940CT-12 I cited above has a dropout of around 0.25v at 500ma. I doubt you would notice any ill effects, if using it to power PWR1 but not PA_PWR1.

Adrian, On the Bitx40, Q13 and R141 can get hot enough to fail on long transmissions, especially if the rig is operating at over 12v.. If feeding it 14.5v, I suggest you add a 3 terminal regulator suc