I'm trying to make a simple Hartley VFO. I've made one before no
problem, but this one won't start, period. The only difference between
this one and the last one is that I used a T50-2 core instead of an air
core inductor. Is that likely to kill it?

Also, last VFO I made, I tested it by feeding it and a signal generator
into a product detector to listen for a tone, this one I'm trying to use
a frequency counter to make things simpler. It reads crystal oscillators
no problem, and I've even used it to read a VFO in another receiver, no
problems.

On Wed, 16 Jul 2003 00:38:38 -0400, Alex wrote:

I'm trying to make a simple Hartley VFO. I've made one before no
problem, but this one won't start, period. The only difference between
this one and the last one is that I used a T50-2 core instead of an air
core inductor. Is that likely to kill it?

Also, last VFO I made, I tested it by feeding it and a signal generator
into a product detector to listen for a tone, this one I'm trying to use
a frequency counter to make things simpler. It reads crystal oscillators
no problem, and I've even used it to read a VFO in another receiver, no
problems.

__________________________________________________ ______________

What type of Hartley is it? If it's one with a separate coil for feedback,
you may have the phasing reversed. Just swap the connections on either the
mail tank coil or the feedback coil, but not both.

--
73, Bill W7TI

On Wed, 16 Jul 2003 00:38:38 -0400, Alex wrote:

I'm trying to make a simple Hartley VFO. I've made one before no
problem, but this one won't start, period. The only difference between
this one and the last one is that I used a T50-2 core instead of an air
core inductor. Is that likely to kill it?

Also, last VFO I made, I tested it by feeding it and a signal generator
into a product detector to listen for a tone, this one I'm trying to use
a frequency counter to make things simpler. It reads crystal oscillators
no problem, and I've even used it to read a VFO in another receiver, no
problems.

__________________________________________________ ______________

What type of Hartley is it? If it's one with a separate coil for feedback,
you may have the phasing reversed. Just swap the connections on either the
mail tank coil or the feedback coil, but not both.

--
73, Bill W7TI

John Popelish wrote:
Alex wrote:

I'm trying to make a simple Hartley VFO. I've made one before no
problem, but this one won't start, period. The only difference between
this one and the last one is that I used a T50-2 core instead of an air
core inductor. Is that likely to kill it?

Also, last VFO I made, I tested it by feeding it and a signal generator
into a product detector to listen for a tone, this one I'm trying to use
a frequency counter to make things simpler. It reads crystal oscillators
no problem, and I've even used it to read a VFO in another receiver, no
problems.


Most likely answer is that you have the phase of the feedback reversed
(negative instead of positive feedback). You should be getting better
coupling with the toroid core, so the optimum turns ration may be one
with fewer turns on the feedback winding, but this would show up as a
very distorted output, not lack of oscillation.




?? I attached the feedback wire about 25% up from the ground as the book
said. See my other posting for a schematic.

John Popelish wrote:
Alex wrote:

I'm trying to make a simple Hartley VFO. I've made one before no
problem, but this one won't start, period. The only difference between
this one and the last one is that I used a T50-2 core instead of an air
core inductor. Is that likely to kill it?

Also, last VFO I made, I tested it by feeding it and a signal generator
into a product detector to listen for a tone, this one I'm trying to use
a frequency counter to make things simpler. It reads crystal oscillators
no problem, and I've even used it to read a VFO in another receiver, no
problems.


Most likely answer is that you have the phase of the feedback reversed
(negative instead of positive feedback). You should be getting better
coupling with the toroid core, so the optimum turns ration may be one
with fewer turns on the feedback winding, but this would show up as a
very distorted output, not lack of oscillation.




?? I attached the feedback wire about 25% up from the ground as the book
said. See my other posting for a schematic.

Alex wrote:
I'm trying to make a simple Hartley VFO. I've made one before no
problem, but this one won't start, period. The only difference between
this one and the last one is that I used a T50-2 core instead of an air
core inductor. Is that likely to kill it?

Also, last VFO I made, I tested it by feeding it and a signal generator
into a product detector to listen for a tone, this one I'm trying to use
a frequency counter to make things simpler. It reads crystal oscillators
no problem, and I've even used it to read a VFO in another receiver, no
problems.



I found my problem, the JFET in my oscillator had it's pins screwed up.
Now it's working fine, and i have a nice 40 meter receiver built. Next I
move on to the transmitter.


73,
Alex
VE3LEG

Alex wrote:
I'm trying to make a simple Hartley VFO. I've made one before no
problem, but this one won't start, period. The only difference between
this one and the last one is that I used a T50-2 core instead of an air
core inductor. Is that likely to kill it?

Also, last VFO I made, I tested it by feeding it and a signal generator
into a product detector to listen for a tone, this one I'm trying to use
a frequency counter to make things simpler. It reads crystal oscillators
no problem, and I've even used it to read a VFO in another receiver, no
problems.



I found my problem, the JFET in my oscillator had it's pins screwed up.
Now it's working fine, and i have a nice 40 meter receiver built. Next I
move on to the transmitter.


73,
Alex
VE3LEG