Re: I have a problem with the original bitx20 version #bitx20help #bitx20

Arv Evans

Possibly one of the mixer diodes is in backwards. 

The original BITX20 had a very sensitive receiver, which allowed 
spurious signals to be heard if there was no RF input and if the 
volume was turned up way too high.  

What is your MDS (Minimum Discernable Signal) in microvolts?
MDS should be in the 0.2 to 0.4 microvolt range.
If you do not have capability to insert a clean 0.2 to 1.5 microvolt 
signal then ignore that test.   

Like all superhet receivers the BFO frequency needs to be adjusted 
to between 10 and 12 db down the side of the crystal filter passband.
Setting it above the filter passband will give you LSB and setting it 
below the filter passband will give you USB reception.  Setting the 
BFO within the filter passband will give you DSB reception.  If you 
set the BFO too far outside the filter passband your received audio 
will be distorted.  where you adjust the BFO relative to the filter 
passband will affect the amount of highs or lows in your received 
signal, and in your transmitted signal.  

Arv  K7HKL

On Sun, Jul 5, 2020 at 11:37 AM dries breughe <driesbreughe@...> wrote:
i built the bitx20 original version in 2012 but it functioned very badly
I built it clean with a PCB board (not the ugly style)

But the reception was rather deaf. except from unwanted beep tones. I suspect unwanted mixing products.
transmitting did not function
I made some modifications based on version 3 and i used a computer controlled vfo
the noise is louder and the beep signals are still there
does anyone have an idea how to solve this problem

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