Crystal filters work at high impedances (1k5 or thereabouts) you will need to use transformers in and out of your circuit to use it with 50 Ohm equipment.
yes you are right, but that is not the intended use. It is to be used to test a Bode measurement. I just needed something that had a sharp transistion for gain and phase. It is not to be used as an actuall filter.
I used to build crystal ladder filters back in the day. You can get great selectivity with them, but you better have a whole bunch of crystals to test with because they are all slightly different and you have to select the most appropriate ones. Your design is *almost* a ladder filter (a classic one also has coupling capacitors between the crystals, and yes there is definitely math to calculate the values of the capacitors).
@@herbertsusmann986 a few tens of ppm is usually most you can achieve. Not really useful for anything than very fine tuning of the center frequency and BW.
@@herbertsusmann986 Open the can and use a clean pencil eraser to pull the crystal by abrasively removing the slightest amount of material. Very old ham trick I have read about but not tried personally, so YMMV or it may not work at all. Good luck.
Do you understand the spectrum of an AM modulated sine wave? This would easily give you a multi-tone signal with easily VARIABLE spacing between the tones! Along with easily variable main frequency. You can thus check the resolution of instruments without building stuff at all kinds of different frequencies. I still can't justify over 9 grand for a scope though. I bought my Keysight scope at full price from them. (2 grand!)
I'm testing the bode plot with the xtal filter. It found an error in the Keysight and they are fixing it. the two freq board with 9v battery was made to put in my pocket when going to an auction or sale to test the RBW of a spectrum analyzer.
When prototyping filters I use the NANOVNA TEST BOARD KIT by TB5CVN available for order as a shared project on PCBWay. You may want to check this out, it a laid out as a proto board for both SMT (x2) and TH (x1) components and has pads for SMA connectors at either end for the SMA connectors for all three filter sections allowing you to do 3 different filters on the same board. All in a 53x32 mm board space, with mounting holes. Good stuff, highly recommended. 73, WA0A
looks nice. I have some too: www.pcbway.com/project/shareproject/VNA_component_test_board_ed12f933.html www.pcbway.com/project/shareproject/Low_Pass_FIlter_RF_Ham_Radio_5eac6a37.html
![ลองสุ่มไอโฟน 990 โกงมั้ย? [ โกงมั้ยครับ ep.101 ] | DOM](http://i.ytimg.com/vi/bfsWe0j492k/mqdefault.jpg)
Congratulations‼️🎉 This is your 2000th video.
Congratulations on reaching episode #2000.
I do the SMT 0805 all the time, makes boards look really neat without passives poking up everywhere, very neat trick indeed!
I like to be able to read the components later so for things like this I actually prefer conventional components
@@Dazzwidd Ah good point!
I mostly do digital stuff, so it's pretty much 10k and 4K7 resistors and some 0.1uf caps sprinkled around
Crystal filters work at high impedances (1k5 or thereabouts) you will need to use transformers in and out of your circuit to use it with 50 Ohm equipment.
yes you are right, but that is not the intended use. It is to be used to test a Bode measurement. I just needed something that had a sharp transistion for gain and phase. It is not to be used as an actuall filter.
@@IMSAIGuywhere did you get your protoboard? I'm looking for one that has VCC and ground under the TTL chips.
www.pcbway.com/project/shareproject/DIY_Protoboard_Digital_Circuits.html
I used to build crystal ladder filters back in the day. You can get great selectivity with them, but you better have a whole bunch of crystals to test with because they are all slightly different and you have to select the most appropriate ones. Your design is *almost* a ladder filter (a classic one also has coupling capacitors between the crystals, and yes there is definitely math to calculate the values of the capacitors).
My biggest problem is that I forget what I built it to do... Now, I document them in a notebook with page number on the fixture.
Have them at my disposal? I have garbage collection for that
Can you make the filters work at different frequencies than what is on the can? I have a bag of either serial txrx chips or ntsc stuff
no
You can pull them slightly with inductors or capacitors but you can't pull the frequency very far.
@@herbertsusmann986 a few tens of ppm is usually most you can achieve. Not really useful for anything than very fine tuning of the center frequency and BW.
@@herbertsusmann986 Open the can and use a clean pencil eraser to pull the crystal by abrasively removing the slightest amount of material. Very old ham trick I have read about but not tried personally, so YMMV or it may not work at all. Good luck.
Would be nice to see the signal without the filter for comparison. 😀
It's just a flat line.
Do you understand the spectrum of an AM modulated sine wave? This would easily give you a multi-tone signal with easily VARIABLE spacing between the tones! Along with easily variable main frequency. You can thus check the resolution of instruments without building stuff at all kinds of different frequencies. I still can't justify over 9 grand for a scope though. I bought my Keysight scope at full price from them. (2 grand!)
I'm testing the bode plot with the xtal filter. It found an error in the Keysight and they are fixing it. the two freq board with 9v battery was made to put in my pocket when going to an auction or sale to test the RBW of a spectrum analyzer.
@@IMSAIGuy OK!
@@IMSAIGuy What was the error in the Keysight? We are interested to know!
@@herbertsusmann986 I'll do a video when the new firmware comes out. We will both see if they fixed it.
Randomly picking load capacitance is going to affect accuracy and drift of those oscillators. All you have to do is check the datasheets.
it's not an oscillator, it's a bandpass filter. as I state in the video is just a quick test circuit. I needed something with sharp transistions.
When prototyping filters I use the NANOVNA TEST BOARD KIT by TB5CVN available for order as a shared project on PCBWay. You may want to check this out, it a laid out as a proto board for both SMT (x2) and TH (x1) components and has pads for SMA connectors at either end for the SMA connectors for all three filter sections allowing you to do 3 different filters on the same board. All in a 53x32 mm board space, with mounting holes. Good stuff, highly recommended. 73, WA0A
looks nice. I have some too:
www.pcbway.com/project/shareproject/VNA_component_test_board_ed12f933.html
www.pcbway.com/project/shareproject/Low_Pass_FIlter_RF_Ham_Radio_5eac6a37.html