Like many in the group I have recently got a new toy - the NanoVNA. As part of my learning curve in how to use a VNA I have been looking at the Bitx40 band pass filter. Attached is the result. I had not expected to find 14dB loss but I guess that is the result of thin wire, small cores. The shape of the response compares well with the predicted plot in the Bitx40 Circuit Description page on hfsignals.com.
73 Brian VK4BAP

My own correction :-p? "edits" not "ends"

73,


Mark

Hi,

In the original (lower resolution) wiring diagram on the wiki ubitx assembly page, and on the higher resolution one I uploaded (I didn't make any ends, I just increased the resolution), the mainboard fuse was specified as 0.5 amps.

Seems that somewhere along the line in Adrian's edits of the wiring diagram, he accidentally changed it to 5 amps.? Can you change that back Adrian?

73,


Mark.

To answer your second question first, yes you can use a second Nano to program and keep the first as originally received.? There are issues that need to be taken into consideration.
1 - The calibration data is stored on the eeprom of the Nano, which is not saved in the CEC software.? You will need to calibrate before it will work correctly, especially the BFO setting.?
2 - The CEC software is different for each display, and the original software only works with the original display.? That would mean that you need to change the Nano AND the display if you do not use the original display version of the CEC software

The first question depends on what you want for a display?? I have the 3.2" that Dr Lee had already created a full screen tft file with the link from the web page.? That is what I would use.? This is a personal choice.? If you want bigger, then you will need to find the correct tft file to match your display.? 2.4 and 3.2 I believe are the two that Dr. Lee has programmed.

You do not need to compile the code if you use the correct hex file.? Use the uBITXV5 directory and read the FileNameInfo.txt file to help select the correct hex file to load into the Nano.? You will need the Hexloader program to go that route.? I believe that this is where I got the version that worked for me:



Incase you did not get it, here is the link to the Git Hub repository zip file:??



This should get you started.

For the calibration process, I would do a search on this site to learn the how to do it.? NOTE that the CEC software does not use the same method as the stock (it does not turn on the transmitter to zerobeat wit another receiver.? For the CEC firmware I would download the Memory Manager that Dr. Lee has created to make the adjustments and save the values after a change to be able to backtrack if something goes wrong.

For the BFO calibration I prefer to use a PC based free audio spectrum analyzer that can be downloaded from here:


I connected a mic to the input of my PC, tuned the uBITX to an open frequency with just static, and adjusted the BFO to center the noise spectra between 500 and 2500 Hz.? I then went back and re-calibrated the maser clock, then back to the BFO for a final time.

The above is what worked for me.? I cannot guarantee that it will for everyone.? I would suggest that you do the search on this sit as stated above.

The above is free advice; it is worth only what you can make of it, and should be checked as well as you can.

Use at your own risk.
73
Evan
AC9TU

@Curt: I'm fine with the 2 amp fuse on the PA PWR line. My question is about the "5 amp" fuse on the +12V line as shown in the wiring diagram I described. As I said before, I was just curious about whether it was a typo (and should, in fact, be 0.5 amps) or whether they really meant 5 amps. I haven't seen anyone recommend a 5 amp fuse on the +12V line anywhere else; only a 0.5 amp fuse. So, I'm inclined to think it might be a typo. If it's a typo, it should probably be fixed.

I’m quite new at this, so please be patient.? I haven't done much with Arduinos yet, but I'm learning...

I assembled my uBITx v.5 and it seems to work OK.? I'm quite happy about that!??It has the stock screen that came with the kit and the stock firmware.? I have two questions:

1. Exactly what do I changes in the CEC Firmware v. 1.2 should I make before uploading it in order for it to run properly on my stock Ver.5 uBITX?? I've read Ian's thread from 2 April 2019, but I want to get this exactly right.? I am not sure exactly how to make the changes I need in order to use my stock display or how to tell the firmware I'm using a Ver. 5 Board. in my uBITx.?

Which display do I select and exactly what characters do I delete or add in front of the display's name in order to select it??

For the my Ver. 5 Board, do I simply type a "5" at the end of the line reading:
"#define UBITX_BOARD_VERSION?"? Is there a space between the "VERSION" and the "5?'

2. I have a spare Arduino Nano.? Can I upload the CEC v. 1.2? firmware to the spare and plug it into the radio and use it, then unplug it and re-insert the original Nano with the stock firmware back in, and use it too?? I mean, can I swap out Arduinos with different Firmware and still expect the radio to perform normally?

?

Thanks,

Martin, AJ6CL

Don't believe everything you read without a little thought, even from me.

Purpose of fuse is circuit protection when a short is experienced. Once I plugged a simple rig someone had sent me to a gel cell, I hadn't checked the wiring but the wires were shorted and caught fire. Lesson learned ...

2 amps might be too low, you want some reasonable margin above expected current flow. 3 to 5 amp fuses should protect it well.

Curt wb8yyy

@_Dave_ K0MBT:?I've got a 2 amp fuse on the PA PWR line and a 0.5 amp fuse on the +12V input line, as I've seen recommended elsewhere. But the wiring diagram reads "5 amp" on the +12V line. I was just wondering if that was a typo (and should be 0.5 amp) or whether it really was suggesting a 5 amp fuse for the +12V line.

I would try a 2 amp.?
--
73
Dave
k0mbt

That amp project is exactly something I would love to have in my Shack! ?

I just wanted to verify the recommended fuse value for the +12V line on the uBITX. The latest wiring diagram, "Wiring Diagram Ubitx V5 V2.0.pdf", shows the fuse as "5 amp Fast Blow" (see lower left of the diagram). In various posts on this forum and elsewhere, however, I've read that the recommended fuse should be 0.5 amps (e.g.,?,?).

Should it be 0.5 amps or 5 amps (or some other value)?

If it should be 0.5 amps, then the wiring diagram needs to be changed.

I entered this contest way back in June
Circuit diagram is done for 160m -2m 200 watt PEP 12 volt mobile amp suitable for ubitx ft817 ft818 ic705 etc
still to actually make the amp module but have the ferrites etc for the in / out circuits

Thanks for all the information regarding the building of the uBITX. I am more so curious about how the RF trace layout was done. I previously built the mcHF to master SMD soldering, and I found that one of the bands didn't work because RF wasn't going through a trace for some reason. I had to solder a piece of wire to fix it. What it essentially meant is that trace layout on a PCB is a little more complex with RF.
Also, it would give me more KiCad design experience. I mean, my school pays for these types of projects, so personal projects I can go all out really.

Thanks,
-Jonathan, KM4CFT

Found the old post.
/Scope:?? 30v Peak to peak / 15 v peak. //
//Calculated Pout:? 2.25 watts RMS, 9 watts peak. /
Not sure what happened to my arithmetic, RMS seems OK but peak should have been 4.5 watts.

Woody

--

On 9/27/2019 14:49, Mark - N7EKU wrote:

Hi Woody,

You've got double the peak power in your original post, which made me wonder how you came up with it.

Without digging out past posts, don't remember what error I made where....
Any issues with my math with my latest reply to Adrien about how to calculate?
Woody

--

Hi Woody,

You've got double the peak power in your original post, which made me wonder how you came up with it.

73,


Mark.

开云体育

"What I don't get is your calculation for peak power?? "

Ben, it can’t be that hard. Just disconnect the connector and see what happens. If the radio still go into transmit it is something else. Did you build in the board? Maybe a shortcut under the main board??