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Allison Sounds good.? Then for the power challenged one could put the LCD backlight on a push-button so it would only be on when needed.? Arv _._ On Mon, Aug 13, 2018 at 1:25 PM ajparent1/KB1GMX <kb1gmx@...> wrote:
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Re: Harmonics
Try this for the existing 20/17/15 LPF? ....make the three coils all 350nH with a 47pF in parallel (easy to tack on), the capacitors at the ends are both 220pF, the other two are both 360pF. Like Allison (and everyone else....) says, the spurs move with tuned frequency.....these traps are for ~39MHz and only to vary the LPF roll-off, not to "trap" any 23.xx MHz.
73 Kees K5BCQ |
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Re: Nextion Basic 3.2 Display will not update
#ubitx
V Zecchinelli
toggle quoted message
Show quoted text
Try with another SD card I changed 4 cards . |
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Re: Harmonics
>>>have been playing with simulation of the 15 meter spur problem.? It seems that?
a series LC trap on the filter output might work but only if the trap has very low?
resistance and if it is exactly on the spur frequency.? Even then LTSpice simulations?
indicate that a couple of db might be lost on the upper end of 15M.? When I added?
a few ohms to the trap to make it broader it caused loss that extended well into the?
ham band.??<<<
Arv, Consider a series connected parallel tuned trap (High L, low C). I tried a series trap and the amp went into oscillation at the trap tuned frequency. I quickly abandoned that approach. Allison ? |
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Re: Nextion Basic 3.2 Display will not update
#ubitx
V Zecchinelli
开云体育Thanks Joe.? I tried 2 SD cards I had but I have used them many
times in RPI projects so I have ordered a couple new ones.? For
power I tried USB port on PC and 5V 3A supply I use with QRP-LABS
U3S so I know it is good.? I have also ordered a USB-TTL cable.? 73 Vince N1VIN
On 8/13/2018 2:01 PM, Joe wrote:
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Re: Nextion Basic 3.2 Display will not update
#ubitx
V Zecchinelli
开云体育Thanks a lot Pat.? I found the cable on Amazon and it is on it's way.? I very much appreciate your input. 73 Vince N1VIN
On 8/13/2018 3:28 PM, pat griffin
wrote:
I am not home and it has been a bit since I did it. You will need an ftdi usb to serial cable ($15 or so) Connect it to the computer USB port and the other end (4 pins) to the 5v, grd, rx, and tx pins on the display. Then select the port in the editor and the download or upload I forget what it is called. I may have left out a step but that’s basically it |
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Re: Nextion Basic 3.2 Display will not update
#ubitx
开云体育I am not home and it has been a bit since I did it. You will need an ftdi usb to serial cable ($15 or so) Connect it to the computer USB port and the other end (4 pins) to the 5v, grd, rx, and tx pins on the display. Then select the port in the editor and the download or upload I forget what it is called. I may have left out a step but that’s basically it
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Arv,
If using an external filter box and the uBITX internal filters remain in place,? it seems that the external filters would only need to be activated in transmit?
mode.? That could save some power when in receive mode.?? As is they are wired to only be active on TX.? The only get power when K1 supplies "TX" (K1 pin 1) voltage to the transmit hardware and that includes KT1-3 and K3. With that said .... one can disable all but K3 and with three etch cuts and jumper TX RF direct to K3 pin16 around the filters completely.? It should save about 120-150 mA. Allison |
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Re: Low Power Output for Hendricks BitX20A - Watt meters and Scope readings do not agree....
#bitx20
Timothy,
>>all due respect Allison Bitx20A is a dual IRF510/A? class B? design with substantial drive frm small signal drivers . What is a bitx20A??? Also I made no assumption any Bitx has a Class A amp most builds I've seen would either oscillate or melt at 1-2 A no signal drain current.? ? Most people run them starved at 50ma to lower the gain of the IRF510 and that near class B. I built the bitx20 and it was a single device. Maybe? your talking about the hendricks bitx20 could as it had BS170 push pull driving IRF510 push pull? However, its was unspecified so I covered the known case. For the Hendricks they could do much more if they didn't break into oscillation first.? Most I got to see were better power oscillators than transmitters.? Minor changes tamed them and usual was 12-15W. Both cases 70V PP would be 24W output across 50ohms , you would only get that with the PA at more than 18V.? or its an incorrect measurement. Allison |
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Re: Sunday
david.g3ryp <david.g3ryp@...>
06/20/04???#30??
>>>I wonder how much output everyone's getting from the IRF510?? <<<
?
The IRF510 is a power MOSFET with max ratings of 5.6A, 100V, and 43W power dissipation ratings. There? are a few "yes but..." around those but for the moment we dispense with that. The power you can obtain is a function of two things the devices gain (well over 13db power gain) and the amount of drive power.? There is a maximum for drive power as you can literally burn out the MOS (metal oxide layer) of the fet. The hard DC limit for that is 20V, so the AC peak to peak should be well under that.? In practical circuits that works the real voltage is much less typically under 6V. Now class of operation: Class A The current flows at the output waveform for the full 360 degrees of a cycle at the output.? You depart Class A if the current required causes an? increase in operating? current.? An IRF510 biased at 2A will do at 12V about 24W input power and about 8W output power (and lots of heat use a good heatsink!).? This means usually has a low efficiency?typically 30% or so. Class B? The current flows only for half the cycle.? This is more efficient but care has to be taken to keep the signal clean at the output connector.? It can be non-linear as well distorting SSB. Class C The current flow is less than 180 degrees (half cycle) and is more of a pulse. With good output filters this produces efficiency in the 70% region and for CW or? high level AM (plate,collector or drain) modulated amplifiers.? Not used for SSB! For some applications and to obtain better efficiency? we can bias between Class A and Class B and this is very common with Class AB or AB1 being the usual for big tube linear amps and many of the solid state types.? The number after the AB generally signifies how fare between pure Class A and pure Class B we are. The typical use of IRF510 is class AB or abouts with a minimum of 50 mA of bias. It is not always optimal and will depend heavily with the design of the amplifier. Generally it does not determine over a wide range what the power out will be. So if you some radio that only gets 2w or a friend that gets 20 the real reason is clearly not the IRF510.? it comes down to if you only get 2W its likely becase you only put in maybe 50mW and the other guy put in 1W.?? Allison |
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Re: Nextion Basic 3.2 Display will not update
#ubitx
V Zecchinelli
开云体育Thanks Pat.? Sounds like a great idea but not sure I know how to
do that.? Would I cobble together a USB to connect to the 5V, RX,
TX, GND?? At this point the display is not connected to the
uBitX.? I have 5V & GND connected to USB adapter and computer. On 8/13/2018 2:33 PM, pat griffin
wrote:
You could try downloading directly to the display. It’s slow but it would tell you if the display or card is bad. |
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If using an external filter box and the uBITX internal filters remain in place, it seems that the external filters would only need to be activated in transmit mode.? That could save some power when in receive mode.? Arv _._ On Mon, Aug 13, 2018 at 11:44 AM ajparent1/KB1GMX <kb1gmx@...> wrote: Tom |
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Re: Nextion Basic 3.2 Display will not update
#ubitx
开云体育You could try downloading directly to the display. It’s slow but it would tell you if the display or card is bad.73
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Re: Harmonics
Gordon I have been playing with simulation of the 15 meter spur problem.? It seems that a series LC trap on the filter output might work but only if the trap has very low resistance and if it is exactly on the spur frequency.? Even then LTSpice simulations indicate that a couple of db might be lost on the upper end of 15M.? When I added a few ohms to the trap to make it broader it caused loss that extended well into the ham band.? Next tests will be with some of the more exotic filter designs (Chebyshev, etc.) which have sharper attenuation characteristic.? Arv _._ On Mon, Aug 13, 2018 at 11:39 AM Gordon Gibby <ggibby@...> wrote:
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Good points.?
Bill, Yes, it will switch when it sees a new frequency outside the band it is on. --- Gordon, Hope the code is able to help you get a start on your project. --- Howard, I have a comment in the source code, if this is the only filter that sending the output to a dummy load until the filter is selected would be a good idea. For QRP that dummy load could be small and builtin. That may be a good idea in all cases; even as a supplemental filter.?Some modes like SSB might require sampling the measured frequency counts, averaging and throwing out the outliers. That would increase the time to select the filter making a dummy load more important. --- Jack, I'll add the URLs for the libraries. That is a good idea, especially in the case of the frequency counter library.? For anyone trying the code before I do that, both libraries are listed in and installable from the Arduino Library Manager. --- Thanks, I did not want to jump into premature optimizations of the code before I can determine what the real issues will be and can measure and test them. The code is a baseline starting point.? Tom, wb6b |
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Re: Nextion Basic 3.2 Display will not update
#ubitx
Hi, I have seen this issues several times 2. Try another microsd card. Usually one of the above clears the problem Joe VE1BWV On Mon, Aug 13, 2018, 2:47 PM V Zecchinelli <n1vin@...> wrote: I have spent most of today searching through messages and wiki to no avail.? I am using the basic 3.2 Nextion display and am trying to upload the tft file I downloaded from .? SD card is 8Gb and is formatted FAT32 and tft file copied to it.? When I insert the card into the Nextion display it shows Baud:?? 9600 and SD Card Update....... and stalls at that point.? I have waited as long as an hour.? Am? missing something or perhaps I procured a bad Nextion or SD card? |
SV9CVJ Nikos
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