Re: Please explain to me how works the VFO's


Gerard
 

hello,
I did some tests again today. The change on the inductances coming out of the 45 mhz filter did nothing more.
I think it’s at its limits and it lacks sensitivity
I compared the shematic (see pdf)  and that of a V3 --->
https://www.hfsignals.com/wp-content/uploads/2017/12/ubitxv3.pdf             ---->(With also 2N3904).
I see only a pb on schematic on the 1st transistor and the resistance of 220ohm.

The collector is directly connected on the power RX, on µbitx V3, it's pass trought this resistance.
Schematic error and good on the PCB. I will check tomorrow. 
Or it doesn’t matter how it works. A transistor specialist will tell us that. In any case, as already said, we will make the modification if necessary.
There is also a small difference in the 45mhz filter and impedances. (see schématic)
If I test with RFsim 99 the filter made of 2 inductances of 0.8µH and capa of 6.8pf, it indicates a loss of 10db at 45mhz. This is not negligible.
So there’s still a test to be done.
Otherwise, on the 7MHZ, I have a lot of conversations,English, Italian, Deuch, but still weak.You need to stick your ear to the speaker.
Amplificator works fine, I tested it with another source
cdt

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