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Hi Randy,

It sounds like you have a calibration issue or a component(s) INSTALLED that should not be there when using the Raduino as the VFO/LO.? The one other possibility is the BFO may not be aligned correctly.

Let's start with what test equipment do you have to work with?? An oscilloscope, DMM, and frequency counter are tools that make diagnostics easier.

Can you also verify that L4 is not installed?? That is for the analog VFO/LO and should be removed when using the Raduino.

Are there any modifications to the board?

Last on the list is the software that is installed in the Raduino.? Is it original or one of the updates/upgrades that are available that include things like CW options.

I do not have a BITX40.? I have e different version of the ?BiTx that is based on the design of the BITX40, so know a little bit about the operation.? Here is the circuit description on HFSignals web page:

You will use this to trace the signals through the rig.

Let us know what you find out about the points above.
73
Evan
AC9TU

Randy,

Evan asked all the right questions.
However, without yet knowing the answers, I'd say you need to first determin
somehow if the VFO and BFO are working.

If you have access to a shortwave receiver, you should hear the BItx40 BFO at
12.0 mhz when that receiver's antenna is near the BItx40.
A finger around L5 and C102 should cause a small frequency change.
A modified Bitx40 may have disabled the 12mhz crystal oscillator at Q10,
obtaining that 12mhz BFO signal from CLK0 of the Raduino instead.

On a very old Bitx40, the varicap diode at D9 and the coil at L4 were used
to tune that oscillator at Q9 with a potentiometer across the TUNING1 connector.
When the Raduino was added in December 2016, the oscillator at Q9 was
disabled by removing L4, and then driving the DDS1 connector with CLK2
from the Raduino for the VFO.? On a stock Bitx40 tuned to 7.00 MHz the VFO
should be within 3 khz of 12-7.00=5mhz.? On some?modified Bitx40's?
the Raduino's VFO may be operating at 12+7.00=19mhz instead.
If the Raduino is working, you should be able to hear that 7mhz or 19mhz
signal on the receiver as well.

Of course, if you have access to an oscilloscope or spectrum analyzer,
those could be used to check the BFO and VFO as well.


A good high resolution schematic should be available here:
? ??
under the tag "Download the circuit diagrams".
Unfortunately that link is broken, so I am attaching the schematic for the Bitx40 to this post.
That is the only version of the Bitx40 schematic with Raduino that was ever made available.

There are some minor corrections to be made to that schematic:
All transistors labeled BC849 are actually stuffed with MMBT3904's (the surface mount version of the 2n3904)
C93, C103, and R105 are not stuffed, R105 has all three terminals shorted together.
D15 and D16 are packaged together in one BAT54S surface mount part.

I would recommend not exceeding 12 volts dc.
At 13 or 14 volts there is a risk of burning out some of the parts.

Be sure you have a good enough antenna to capture signals on the air.
This radio is designed to work best with a resonant 50 ohm transmitting antenna.
With at least 10 meters of wire laid across the floor for an antenna, you should start hearing signals.

In some cases, the BNC connector was not machined precisely enough, and the center pin
did not make contact.? Make sure you really do have a connection to the antenna.

If you bought this used, it may have been sold for a reason.

Jerry, KE7ER

The broadcast that you're hearing is just AM broadcast breaking through to the audio amplifier circuit, which is the LM386. It might even be making it through the rest of the receiver. It doesn't indicate anything special. What I'd recommend doing is tuning down to the 7.077 region to see if you can hear the FT8 signals. They're at 7.074 *upper* sideband, so if you tune to 7.077 you'll hear them on the *lower* sideband just fine. That will help you figure out if it is working. You can also use a Web SDR near you to listen to strong signals and see if you can tune them.?

Post pictures of your build so we can help more, and let us know how it goes :)?
--
Ryan Flowers - W7RLF