Please let us know how this board works out. My biggest concern would be that it probably would need to be constantly queried. For example; If you wanted to put the tuning knob on it, then it would ne

#ubitx

Hello Adrien, That is not an AGC circuit, but is just a limiter circuit. No "clack" elimination but it does limit how strong it appears in your ears. It is hearing protection. I have installed that in

Here is what I use: A dynamic mic element feeding a 3-component common-base amplifier. Fits right inside the microphone case. Matches the 600 ohm element to the pre-amp and great frequency response. D

John, In the vicinity of 10 millivolts for a readable signal at moderate volume. Consider it comparable to "line" levels for your stereo amplifier. 73, Don

Sergio: Here are two : http://www.nd6t.com/bitx/documentation/encoder 73, Don

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Since the path from tuner to ground becomes more significant at higher frequencies I have found that tuning the ground with a variable series LC circuit helps incredibly. Otherwise it is frequent that

Looking at the picture it appears that you have not attached the switch. Without a discharge path from the common (S meter, AGC voltage) to ground then C6 will remain charged and the attenuating trans

I converted a power supply so that it now has a panel voltmeter and installed a voltage control on the front panel. Now when I need to adjust RF output a bit lower I can drop it quickly by lowering th

Replace 1 resistor. 470 ohms is a good choice. Saves a bit of current, makes the display last longer, less heat. Here's the link to how and where: http://www.nd6t.com/bitx/Backlight dimming I do this

I placed mine right at the output (wiper) of the volume control. I built mine from an LM380. I also placed a switchable 200 Hz wide CW filter between that point and my new audio amp. A throw of a togg

Hi Digger, Often the simplest of things are revealed as complex. As Jerry says, the delays are important. The values used allows the attenuation to smoothly increase and track the signal level variati

Daniel, check the voltage at the junction of C1, R3, and the gate of Q1 and Q3 when the PTT is active. That should be near zero. Q3 is the receive audio gate and should be open when transmitting. If t

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I have had 2 of the original volume controls with similar problems. The contact pin rivets had intermittent connections to the resistance substrate. They were going open. I changed to 10K audio taper

Pat, Just wire the PA power to the switch in addition to the rest of the radio. It was intended as a means to supply the RF power amplifier with a higher voltage if desired. That also makes it easier

Jim, Why a separate AM detector? When the reference oscillator is calibrated then you just tune to the carrier frequency and it is zero beat. I've been listening to broadcast on the BITX since I first

Hi Daimon, I would suggest that you switch it out. With FT8 you will have several signals present within the pass band, some quite strong, others below the noise. Any strong signals that reduce your g

Curt, Just to make sure, I opened up my uBIITX and checked voltages. With a 50 uV (S9, -73 dBm) there was about 1 to 2 millivolts RMS on the top of my volume control. But with 1,000 uV (about S9+27, -

I'm just sorry to hear that it isn't working for you. From your description it all seems correct. It would be nice if there was some substantial signal that you could tune to, something steady and str

What is the voltage on the base of Q1? What signal source are you using when you see no voltage output? Are you measuring at the junction of C3, R3, the cathode of D2, and the gate of Q2 to ground? Di

The discharge resistance is provided in the AGC circuits in the form of the AGC hold time resistors (R6 through 9 in the kit, R6 in the hand-made version). My concern is the analog reading method sinc