Is this the correct result?


Michael LeBlanc
 

I've just completed building a PHSNA and Power Meter. I've put the boards in their respective boxes. I have the Measurement Receiver and Crystal Test Fixtures half built, but I thought that I'd try out what I have to see if what I have so far works ok. I'm using the Arduino sketch SimpleSNA_WA5BDU_1r10_rev2r62. 


As a test, I found a simple IF can recovered from an old radio receiver (a TOKO type) and connected it up to see if I can detect a peak. I'm running this on a Mac and I don't have Excel so I'm copying and pasting the data into Plot2. I get something that looks credible, but there's no peak--instead, it's a very nice dip from -6dB to -23dB at around 455kHz. View the plot.


I'm not grasping why there's a drop in voltage at what I presume is the resonant frequency. Am I on the right track here, or do I have my wires crossed somewhere (either in my head or in the equipment)?


Michael VE1LEB



Todd K7TFC
 

Just a few thoughts. Looking at your test circuit, I wondered if you should hook a load to the output of the IF transformer to get a predictable result, but I also think that the dip you measured is the classic resonance dip when a circuit at resonance presents minimum impedance and therefore minimum voltage drop across it.

Todd K7TFC


On Oct 1, 2016 10:02 AM, "michaelleblanc1@... [PHSNA]" <PHSNA@...> wrote:
 

I've just completed building a PHSNA and Power Meter. I've put the boards in their respective boxes. I have the Measurement Receiver and Crystal Test Fixtures half built, but I thought that I'd try out what I have to see if what I have so far works ok. I'm using the Arduino sketch SimpleSNA_WA5BDU_1r10_rev2r62. 


As a test, I found a simple IF can recovered from an old radio receiver (a TOKO type) and connected it up to see if I can detect a peak. I'm running this on a Mac and I don't have Excel so I'm copying and pasting the data into Plot2. I get something that looks credible, but there's no peak--instead, it's a very nice dip from -6dB to -23dB at around 455kHz. View the plot.


I'm not grasping why there's a drop in voltage at what I presume is the resonant frequency. Am I on the right track here, or do I have my wires crossed somewhere (either in my head or in the equipment)?


Michael VE1LEB



EB4APL
 

Michael,

Since you have not connected the can as a transformer (i.e a winding as input and the other as output) but you connected just the resonant primary between the output and the input (the open secondary is not doing anything), you obtained what you must expect: the high attenuation of parallel resonant circuit.

If you connect the primary to the generator and the secondary to the detector you will get the transfer curve of the resonant transformer with a peak at the resonant frequency.

Regards,

Ignacio EB4APL



El 01/10/2016 a las 19:00, michaelleblanc1@... [PHSNA] escribió:
 

I've just completed building a PHSNA and Power Meter. I've put the boards in their respective boxes. I have the Measurement Receiver and Crystal Test Fixtures half built, but I thought that I'd try out what I have to see if what I have so far works ok. I'm using the Arduino sketch SimpleSNA_WA5BDU_1r10_rev2r62. 


As a test, I found a simple IF can recovered from an old radio receiver (a TOKO type) and connected it up to see if I can detect a peak. I'm running this on a Mac and I don't have Excel so I'm copying and pasting the data into Plot2. I get something that looks credible, but there's no peak--instead, it's a very nice dip from -6dB to -23dB at around 455kHz. View the plot.


I'm not grasping why there's a drop in voltage at what I presume is the resonant frequency. Am I on the right track here, or do I have my wires crossed somewhere (either in my head or in the equipment)?


Michael VE1LEB



Posted by: michaelleblanc1@...





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EB4APL
 

Michael,

Since you have not connected the can as a transformer (i.e a winding as input and the other as output) but you connected just the resonant primary between the output and the input (the open secondary is not doing anything), you obtained what you must expect: the high attenuation of parallel resonant circuit.

If you connect the primary to the generator and the secondary to the detector you will get the transfer curve of the resonant transformer with a peak at the resonant frequency.

Regards,

Ignacio EB4APL



El 01/10/2016 a las 19:00, michaelleblanc1@... [PHSNA] escribió:
 

I've just completed building a PHSNA and Power Meter. I've put the boards in their respective boxes. I have the Measurement Receiver and Crystal Test Fixtures half built, but I thought that I'd try out what I have to see if what I have so far works ok. I'm using the Arduino sketch SimpleSNA_WA5BDU_1r10_rev2r62. 


As a test, I found a simple IF can recovered from an old radio receiver (a TOKO type) and connected it up to see if I can detect a peak. I'm running this on a Mac and I don't have Excel so I'm copying and pasting the data into Plot2. I get something that looks credible, but there's no peak--instead, it's a very nice dip from -6dB to -23dB at around 455kHz. View the plot.


I'm not grasping why there's a drop in voltage at what I presume is the resonant frequency. Am I on the right track here, or do I have my wires crossed somewhere (either in my head or in the equipment)?


Michael VE1LEB



Posted by: michaelleblanc1@...





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