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IRFZ24N

#sBitx

Randy N3PUT All Messages By This Member #103022 I just received my sBitx-v2 ! There is a bag of parts, power cord, 3.5mm jack and two transistors...I think? They are listed in the parts list as IRFZ24N What are they for? Be nice I'm new.
Shirley Dulcey KE1L All Messages By This Member #103023 The IRFZ24 transistors are spares for the final output stage, just in case you damage them. Unless something goes wrong you won't need them. toggle quoted message Show quoted text On Thu, Jun 15, 2023 at 2:09?PM Randy N3PUT <randy@...> wrote: I just received my sBitx-v2 ! There is a bag of parts, power cord, 3.5mm jack and two transistors...I think? They are listed in the parts list as IRFZ24N What are they for? Be nice I'm new.
Dave AB7E All Messages By This Member #103025 开云体育 When I look at the data sheet for the IRFZ24, the typical Ton/Toff delay times add up to about 40 nsec, which I think translates roughly to about 25 MHz.? That seems to me to be a bit marginal.? I assume that the factory outgoing tests assure that shipped units meet the 40 watt power spec on all bands, but since there is no maximum Ton/Toff delay times spec'd by the manufacturer I wonder if the folks who have had to replace their PA FETS might get units that don't actually give full output. Or is my math (or understanding) wrong? Thanks for any clarification. 73 es take care, Dave?? AB7E On 6/15/2023 11:23 AM, Shirley Dulcey KE1L wrote: toggle quoted message Show quoted text The IRFZ24 transistors are spares for the final output stage, just in case you damage them. Unless something goes wrong you won't need them. On Thu, Jun 15, 2023 at 2:09?PM Randy N3PUT <randy@...> wrote: I just received my sBitx-v2 ! There is a bag of parts, power cord, 3.5mm jack and two transistors...I think? They are listed in the parts list as IRFZ24N What are they for? Be nice I'm new.
Randy N3PUT All Messages By This Member #103028 Thank you...I was hoping that would be the answer!
ajparent1/kb1gmx All Messages By This Member #103029 Dave, Ton and Toff do not apply in analog use.? Those are saturated switch numbers. Unlike bipolar MOSFETs do not exhibit FT (Frequency where gain goes to 1).. They sorta do but the mechanism is different. For example I've used IRF510s at 70mhz and they are real good at 50mhz. I see no reason the IRFz24 would be different save for the input C is greater so the matching is more critical as you go up in frequency. -- Allison ------------------ Please use the forum, offline and private will go to bit bucket.
Dave AB7E All Messages By This Member #103033 开云体育 Yes, they do apply in analog use.? They aren't directly applicable, but they represent the ability of the device to change voltage level.? A slow switch is going to have a low Ft.? The IRF510 is literally twice as fast a switch as the IRZ24N ... at least at their recommended bias conditions. I worked in the discrete semiconductor industry (engineer, then business manager) for over 30 years.? Saturation certainly affects the turn on delay (how hard are you driving it to put it into saturation) and turn off delay (how hard was it saturated), but it doesn't significantly affect the rise and fall times as the device traverses the linear region. Besides, I was actually asking more about the effect of possible variations from batch to batch.? The listed specs only give typicals ... and trust me, as an ex-producer of semiconductors I know that variations can be significant. Dave?? AB7E On 6/15/2023 3:54 PM, ajparent1/kb1gmx wrote: toggle quoted message Show quoted text Dave, Ton and Toff do not apply in analog use.? Those are saturated switch numbers. Unlike bipolar MOSFETs do not exhibit FT (Frequency where gain goes to 1).. They sorta do but the mechanism is different. For example I've used IRF510s at 70mhz and they are real good at 50mhz. I see no reason the IRFz24 would be different save for the input C is greater so the matching is more critical as you go up in frequency. -- Allison ------------------ Please use the forum, offline and private will go to bit bucket.
Ashhar Farhan All Messages By This Member #103035 Dave, This is the reason why we have this painful tx calibration routine to level the output. The device variations are prettt wide. toggle quoted message Show quoted text On Fri, Jun 16, 2023, 8:26 AM stone_ridge_road <AB7Echo@...> wrote: Yes, they do apply in analog use.? They aren't directly applicable, but they represent the ability of the device to change voltage level.? A slow switch is going to have a low Ft.? The IRF510 is literally twice as fast a switch as the IRZ24N ... at least at their recommended bias conditions. I worked in the discrete semiconductor industry (engineer, then business manager) for over 30 years.? Saturation certainly affects the turn on delay (how hard are you driving it to put it into saturation) and turn off delay (how hard was it saturated), but it doesn't significantly affect the rise and fall times as the device traverses the linear region. Besides, I was actually asking more about the effect of possible variations from batch to batch.? The listed specs only give typicals ... and trust me, as an ex-producer of semiconductors I know that variations can be significant. Dave?? AB7E On 6/15/2023 3:54 PM, ajparent1/kb1gmx wrote: Dave, Ton and Toff do not apply in analog use.? Those are saturated switch numbers. Unlike bipolar MOSFETs do not exhibit FT (Frequency where gain goes to 1).. They sorta do but the mechanism is different. For example I've used IRF510s at 70mhz and they are real good at 50mhz. I see no reason the IRFz24 would be different save for the input C is greater so the matching is more critical as you go up in frequency. -- Allison ------------------ Please use the forum, offline and private will go to bit bucket.
Dave AB7E All Messages By This Member #103037 开云体育 That makes a lot of sense.? So the TX calibration is required if it is necessary to change the finals, correct??? Does that hold up over a normal temperature range?? I don't mean a full commercial temperature range ... just what might be expected during typical usage. Thanks again es 73, Dave?? AB7E On 6/15/2023 10:48 PM, Ashhar Farhan wrote: toggle quoted message Show quoted text Dave, This is the reason why we have this painful tx calibration routine to level the output. The device variations are prettt wide. On Fri, Jun 16, 2023, 8:26 AM stone_ridge_road <AB7Echo@...> wrote: Yes, they do apply in analog use.? They aren't directly applicable, but they represent the ability of the device to change voltage level.? A slow switch is going to have a low Ft.? The IRF510 is literally twice as fast a switch as the IRZ24N ... at least at their recommended bias conditions. I worked in the discrete semiconductor industry (engineer, then business manager) for over 30 years.? Saturation certainly affects the turn on delay (how hard are you driving it to put it into saturation) and turn off delay (how hard was it saturated), but it doesn't significantly affect the rise and fall times as the device traverses the linear region. Besides, I was actually asking more about the effect of possible variations from batch to batch.? The listed specs only give typicals ... and trust me, as an ex-producer of semiconductors I know that variations can be significant. Dave?? AB7E On 6/15/2023 3:54 PM, ajparent1/kb1gmx wrote: Dave, Ton and Toff do not apply in analog use.? Those are saturated switch numbers. Unlike bipolar MOSFETs do not exhibit FT (Frequency where gain goes to 1).. They sorta do but the mechanism is different. For example I've used IRF510s at 70mhz and they are real good at 50mhz. I see no reason the IRFz24 would be different save for the input C is greater so the matching is more critical as you go up in frequency. -- Allison ------------------ Please use the forum, offline and private will go to bit bucket.
ajparent1/kb1gmx All Messages By This Member #103048 Yes and recommended conditions are for SMPS and similar operations where the device is saturated.? Not the graph,? charge on the gate to specify operating behavior? its about the amount of charge that the capacitive gate has to acqure and have removed to switch. For analog comparing switching times and slew rate are not the same parameters. To get to a switching time you need only look at the switching wave for and measure the? current (Not voltage) at the required RF driving load impedance which is lower than their inductive or resistive examples.?? The driving impedance specified is 24ohms (switching) and the gate impedance at 28mhz is about 20 ohms that limits how fast you can change the voltage on the gate.? Make the drive stiffer (lower impedance and higher peak current) and you get faster times. So the real limit (for HF) is how fast can you change the voltage on the gate (370pf series with 7.5nh) for a much narrower change than switching would require?? That is a function of driving impedance and power. Also the gain of the device is minimum 4.5S so that means a 1V change on the gate is 4.5A drain current and 2 to less than 4V peak (plus bias) is required to get a drain current (less than 10A) change sufficient to get 40W out. That also does not take into account that for step changes (PULSE) the gate to drain capacitance acts as miller integration or negative feedback? that will be influenced by gate driving impedance.? Make that drive impedance low enough and VHF is easily possible.?? As a result saturation is never approached and the slew rate is not limited by the device behavior but the circuit constants that change with frequency. An aside, look at the hard switching number for many tubes, you'd wonder? how they did radar (pulse switches). ? -- Allison ------------------ Please use the forum, offline and private will go to bit bucket.

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