Re: BITX20 made in brasil...!!

Chris van den Berg
 

Hi all,
the information that I posted before, does contain a major mistake!
I was forgotten that the 10 dB attenuator was still connected while
measuring the output of Q14. So the output was not 0,3 mw but 3 mw.
However, now I measured again and the output of Q14 is 1,2 mw and
the output of the 2N2219 (2N2218) is now 80 mw (gain of 18dB).
I wonder where the 3 dB went (may be this is the negative aspect of
adding shielding ;-( )

Increasing of the oscillator level did not result in better
functioning mixer (it can be tested easily by adding a 0,1 uF
capacitor over the 1K resistor between Q8 and Q9).

By the way, adding a RFC on the 100 ohm potmeter (in the mixer) gave
a better reduction of the AF component, however, the AF component
will not pass the filter.

Sorry for posting the wrong information,
Chris.

some additional measurement results (all loaded with 50 ohm):
The output of Q14 is 0.3 mw, output of the 2N2219 about 150 mw
(with much LF in the microphone stage). This means a gain of 27 dB
(but I am sure you should not measure it all with 50 ohm load).
Chris.

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