Base Bias tuned 40m VFO

[VA7AAX]

here is an interesting circuit I saw today

http://www.qrp.pops.net/base_bias_vfo.asp

I am going to knock one my version soon. will report on this thread.

hmm...
This might lead to a simple rcvr beig built around it.

interesting idea nonetheless.

Check out the rest of the QRP popcorn website as well.
The SSB trasceivers look real well

73 de va7aax

[AC0FP]

here is an interesting circuit I saw today

http://www.qrp.pops.net/base_bias_vfo.asp

I am going to knock one my version soon. will report on this thread.

hmm...
This might lead to a simple rcvr beig built around it.

interesting idea nonetheless.

Check out the rest of the QRP popcorn website as well.
The SSB trasceivers look real well

73 de va7aax

This is a common method for frequency modulating a VCO controlled by a synthesizer circuit.

73,

Frank:)

[AF6LJ]

here is an interesting circuit I saw today

http://www.qrp.pops.net/base_bias_vfo.asp

I am going to knock one my version soon. will report on this thread.

hmm...
This might lead to a simple rcvr beig built around it.

interesting idea nonetheless.

Check out the rest of the QRP popcorn website as well.
The SSB trasceivers look real well

73 de va7aax

Now that is interesting albeit not very linear in terms of frequency / voltage. Sort of like miller effect for transistors (perhaps not).
one thing is for sure the load across the tank drops as the voltage is increased.

;)

Just think of the fun you could have building a temperature compensation circuit for that VFO to keep it stable in the real the real world.

Definitely a fun toy to while the hours away with.
I might have to play with that when I have the two other projects waiting for my attention out of the way.

[VA7AAX]

thanks for the interesting input. well, cant really expect a linear tuning range for $5-10. =)

yeah, I too have a project in attention so once I get it built I will report on how I find it.

73 de va7aax

[N0WVA]

Seems to me that the circuit would drift a bit every time you re-tuned. As bias increases, so does drift because the junction would heat and change capacitance.

I prefer FET's, but perhaps you would be able to get this circuit to fly right.