Dear sir,

As I understood that a regenerative radio has a feed-back loop at the
detector stage, while Q-multiplier has it at IF strip. Has any body
tried the feed-back loop at RF stage itself.

I'm thinking of homebrewing a "tunable preselector" with a very narrow
bandwidth. If we can implant the Q-multiplier concept into the tunable
preselector, it should be very much cheaper than building one from a
combination of coroidal cores to get the best Q factor.

Best regards,
Amin

Hello Amin

I'm thinking of homebrewing a "tunable preselector" with a very narrow
bandwidth. If we can implant the Q-multiplier concept into the tunable
preselector, it should be very much cheaper than building one from a
combination of coroidal cores to get the best Q factor.

The idea is known as a regenerative preselector and there is a
lot of them on the net.

Regards Max

Max wrote:
Hello Amin


I'm thinking of homebrewing a "tunable preselector" with a very narrow
bandwidth. If we can implant the Q-multiplier concept into the tunable
preselector, it should be very much cheaper than building one from a
combination of coroidal cores to get the best Q factor.


The idea is known as a regenerative preselector and there is a
lot of them on the net.

Regards Max



1967 ARRL HB had a receiver with an RF Q multipler.

Max,

I've been looking for a regenerative preselector on the net but can't
find any. The few links I did find are broken.

I also looked at Q-multipliers, but there was no theory available for
me to understand how I could construct one to work at RF, let alone
couple it into the RF signal path.

Hints, please?


1967 ARRL HB had a receiver with an RF Q multipler.

I don't have access to this. Can you email me the schematic? Doing
this is fair use, not a copyright violation.

Thanks,

The Eternal Squire


Amin,

I have some good news. I, too, had felt the need for a 3 khz
bandwidth
tunable preselector, so I had been exploring gyrator-based filter
circuits
where I substitute FETS for the resistors in the gyrators and then
apply
voltage to the grids of the FETS for voltage tuning.

In a 3rd-order pi bandpass circuit in LTSpice using gyrators made from
Maxim
1Ghz bandwidth op-amps, the voltage tuning part works nicely from up
to 30 Mhz, but the selectivity is about 150khz to 250khz. I do no
better with higher
order filters, which I suppose is par since all I am using is an LC
design
even though the L's are now all gyrators.

Looking for better selectivity, I happened about the Q-multiplier
discussions,
only to find few circuits and no explanations. The few I saw
indicate a fixed
tank circuit as the basis of the regenerative oscillator.

I think if we take a working example of an regenerative preselector
and
subsitute a gyrator-based tank circuit, we can get a voltage tunable
rf regenerative preselector, which is what we both want!

So, if you can find the preselector, I can try to simulate it in
LTSpice
with the gyrator-based tank I've designed.

What do you think?

The Eternal Squire


scharkalvin wrote in message ...
Max wrote:
Hello Amin


I'm thinking of homebrewing a "tunable preselector" with a very narrow
bandwidth. If we can implant the Q-multiplier concept into the tunable
preselector, it should be very much cheaper than building one from a
combination of coroidal cores to get the best Q factor.


The idea is known as a regenerative preselector and there is a
lot of them on the net.

Regards Max



1967 ARRL HB had a receiver with an RF Q multipler.

Max,

I've been looking for a regenerative preselector on the net but can't
find any. The few links I did find are broken.

I also looked at Q-multipliers, but there was no theory available for
me to understand how I could construct one to work at RF, let alone
couple it into the RF signal path.

Hints, please?


1967 ARRL HB had a receiver with an RF Q multipler.

I don't have access to this. Can you email me the schematic? Doing
this is fair use, not a copyright violation.

Thanks,

The Eternal Squire


Amin,

I have some good news. I, too, had felt the need for a 3 khz
bandwidth
tunable preselector, so I had been exploring gyrator-based filter
circuits
where I substitute FETS for the resistors in the gyrators and then
apply
voltage to the grids of the FETS for voltage tuning.

In a 3rd-order pi bandpass circuit in LTSpice using gyrators made from
Maxim
1Ghz bandwidth op-amps, the voltage tuning part works nicely from up
to 30 Mhz, but the selectivity is about 150khz to 250khz. I do no
better with higher
order filters, which I suppose is par since all I am using is an LC
design
even though the L's are now all gyrators.

Looking for better selectivity, I happened about the Q-multiplier
discussions,
only to find few circuits and no explanations. The few I saw
indicate a fixed
tank circuit as the basis of the regenerative oscillator.

I think if we take a working example of an regenerative preselector
and
subsitute a gyrator-based tank circuit, we can get a voltage tunable
rf regenerative preselector, which is what we both want!

So, if you can find the preselector, I can try to simulate it in
LTSpice
with the gyrator-based tank I've designed.

What do you think?

The Eternal Squire


scharkalvin wrote in message ...
Max wrote:
Hello Amin


I'm thinking of homebrewing a "tunable preselector" with a very narrow
bandwidth. If we can implant the Q-multiplier concept into the tunable
preselector, it should be very much cheaper than building one from a
combination of coroidal cores to get the best Q factor.


The idea is known as a regenerative preselector and there is a
lot of them on the net.

Regards Max



1967 ARRL HB had a receiver with an RF Q multipler.

Max wrote:
Hello Amin


I'm thinking of homebrewing a "tunable preselector" with a very narrow
bandwidth. If we can implant the Q-multiplier concept into the tunable
preselector, it should be very much cheaper than building one from a
combination of coroidal cores to get the best Q factor.


The idea is known as a regenerative preselector and there is a
lot of them on the net.

Regards Max



1967 ARRL HB had a receiver with an RF Q multipler.

Hello Amin

I'm thinking of homebrewing a "tunable preselector" with a very narrow
bandwidth. If we can implant the Q-multiplier concept into the tunable
preselector, it should be very much cheaper than building one from a
combination of coroidal cores to get the best Q factor.

The idea is known as a regenerative preselector and there is a
lot of them on the net.

Regards Max