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Hans Summer's web page 30m transmitter

"Mike"
 

Can anyone tell me the values of the voltage divider resistors biasing LED varicap in the schematic on this page?

I think the upper resistor is 33k but have no clue what the grounded one is.

'QBH
"hanssummers2000"
 

Hi Mike

Can anyone tell me the values of the voltage divider resistors biasing LED varicap in the schematic on this page?

I think the upper resistor is 33k but have no clue what the grounded one is.
Even I can't tell you that, sorry :-( Looks like I shrunk that diagram too much. The good news is that the values are entirely non critical. You could try with 33k in both positions to start with. I believe I chose the values in haste. It was merely to achieve, together with the 100K resistor to the 4-bit digital-to-analogue converter, the right amount of shift that I wanted. No magic to it. I think it's just a matter of playing with the values until you get the shift amount you want, subject to the component tolerances and LED characteristics you have in your circuit.

73 Hans G0UPL
"Mike"
 

Thanks Hans,
I figured I might experiment with that design until you're able to start shipping kits.

73 Mike N0QBH

--- In [email protected], "hanssummers2000" <hans.summers@...> wrote:


Hi Mike

Can anyone tell me the values of the voltage divider resistors biasing LED varicap in the schematic on this page?

I think the upper resistor is 33k but have no clue what the grounded one is.
Even I can't tell you that, sorry :-( Looks like I shrunk that diagram too much. The good news is that the values are entirely non critical. You could try with 33k in both positions to start with. I believe I chose the values in haste. It was merely to achieve, together with the 100K resistor to the 4-bit digital-to-analogue converter, the right amount of shift that I wanted. No magic to it. I think it's just a matter of playing with the values until you get the shift amount you want, subject to the component tolerances and LED characteristics you have in your circuit.

73 Hans G0UPL

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