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Q-Multiplier at RF stage?
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 |
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 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. |
Hello
I took a look at the links. From what I am understanding these are front-end regenerative circuits. I guess that what I can do is instead of using a loop I could use a broadband coupling transformer, and then place the tank in shunt with the output of the coupling transformer. Thing is, I don't understand how the regenerative preamp is different from the regenerative recever (aka regenerative mixer down to baseband audio). Can you enlighten me? Just to make a few things clear, I would like to say. There is no differents between a frontend and a preamp, it is the same only thing is the mechanical layout. The only differents there is between a regenerative reciever and a regenerative preamplifier is that the reciever has a detector, the way of function is the same. I will scan the 4 pages I have with a Q-multiplying preamp and mail them to you, so please tell me if the e-mail adress you are using is valid. Regards Max |
Hello
I took a look at the links. From what I am understanding these are front-end regenerative circuits. I guess that what I can do is instead of using a loop I could use a broadband coupling transformer, and then place the tank in shunt with the output of the coupling transformer. Thing is, I don't understand how the regenerative preamp is different from the regenerative recever (aka regenerative mixer down to baseband audio). Can you enlighten me? Just to make a few things clear, I would like to say. There is no differents between a frontend and a preamp, it is the same only thing is the mechanical layout. The only differents there is between a regenerative reciever and a regenerative preamplifier is that the reciever has a detector, the way of function is the same. I will scan the 4 pages I have with a Q-multiplying preamp and mail them to you, so please tell me if the e-mail adress you are using is valid. Regards Max |
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