Farhan

I haven’t gotten the upgrade parts yet.?

art N2AJO?

Although those Nanos are no-name clones, the key component on them is normally a real Atmel microcontroller. I gather that some clones of the Atmel chip have started to appear; those should be avoided. Every?Nano clone I have bought has an actual Atmel chip. The Arduino designs are open source hardware, and the bootloader is open source software, so clones are completely legal.

The Nano clones use an inexpensive USB to serial chip from China (originally a CH340G; they have now shifted to a CH340C, which is even cheaper because it has a stable onboard frequency reference and does not require a crystal) rather than the FTDI chip used on a real Nano, but that does not affect their operation in ham applications. (You may have to do the extra step of installing a driver on Windows systems the?first time you connect one.) The FTDI chips are stupidly expensive; the Arduino Uno uses a second Atmel microcontroller just for USB-serial conversion because it's cheaper than the dedicated FTDI chip!

On Mon, Sep 5, 2022 at 4:26 PM Jerry Gaffke via <jgaffke=[email protected]> wrote:

Tayda looks like a good steer for a cheap PFET.
But be aware that the on resistance of an IRF5305 is 60 milli-Ohms, which is 20 times more than the part Gordon was working with.
So if your rig draws 10 Amps there will be a 10*0.060=0.6 volt drop across this PFET, and you may as well just use a big Schottky diode in series.

Also, IR/Infineon consider this part to be obsolete, so now only made by no-name second tier clone manufacturers.
For example, these guys list the manufacturer as "various".

Not necessarily a bad thing, there are thousands of uBitx's out there with a clone no-name Nano,
and the Nano is far more complicated than a PFET.

I've bought a bunch of stuff from Tayda at their alarmingly low prices, it all seems to work just fine.

Jerry, KE7ER


On Mon, Sep 5, 2022 at 11:41 AM, JerryP wrote:

If you're looking for a P-Channel MOSFET for a power switch then this may be able to use a IRF5305 - TO-220, 55V, 31A, 0.06Ohm RDS On @$0.78 each:

Tayda has a $5.00 minimum order and their USPS shipment is 8-16 days and low cost.? While they may not have everything, it's very low priced and good quality.

?

toggle quoted messageShow quoted text

Windows 10 and onward includes an SSH client. Just open a cmd window. Can't remember if it needs to be installed. It may be added when you install the Windows Subsystem for Linux. Remember, M$ and Linux are in bed together now ;-)

John K0JD

On 9/4/2022 11:36 PM, Ashhar Farhan wrote:

First, enable ssh on the sbitx.

1. From the main menu, Choose Preferences > Raspberry Pi Configuration

2. Click on the Interfaces tab

3. On the tab and enable SSH if not enabled, Click OK

4. From a terminal on the sbitx, type ifconfig and note the IP address of the sbitx. In my case it was 192.168.1.142

Second, from your linux laptop (yeah, it wont work with windoze, it might work on a mac, let us know)

1. Open a terminal window

2. Enable remote x clients to connect with the command "xhost?+" (without quotes)

3. Next, ssh to your sbitx with a special option like this :

 ssh [email protected] -X

Enter your password (by default it is hf12345).

4. Now you are connected to the sbitx. Go into the sbitx directory 

and execute the program like this:

cd sbitx
./sbitx

Tayda looks like a good steer for a cheap PFET.
But be aware that the on resistance of an IRF5305 is 60 milli-Ohms, which is 20 times more than the part Gordon was working with.
So if your rig draws 10 Amps there will be a 10*0.060=0.6 volt drop across this PFET, and you may as well just use a big Schottky diode in series.

Also, IR/Infineon consider this part to be obsolete, so now only made by no-name second tier clone manufacturers.
For example, these guys list the manufacturer as "various".

Not necessarily a bad thing, there are thousands of uBitx's out there with a clone no-name Nano,
and the Nano is far more complicated than a PFET.

I've bought a bunch of stuff from Tayda at their alarmingly low prices, it all seems to work just fine.

Jerry, KE7ER


On Mon, Sep 5, 2022 at 11:41 AM, JerryP wrote:

If you're looking for a P-Channel MOSFET for a power switch then this may be able to use a IRF5305 - TO-220, 55V, 31A, 0.06Ohm RDS On @$0.78 each:

Tayda has a $5.00 minimum order and their USPS shipment is 8-16 days and low cost.? While they may not have everything, it's very low priced and good quality.

?

toggle quoted messageShow quoted text

Tayda looks like a good steer for a cheap PFET.
But be aware that the on resistance of an IRF5305 is 60 milli-Ohms, which is 20 times more than the part Gordon was working with.
So if your rig draws 10 Amps there will be a 10*0.060=0.6 volt drop across this PFET, and you may as well just use a big Schottky diode in series.

Also, IR/Infineon consider this part to be obsolete, so now only made by no-name second tier clone manufacturers.
For example, these guys list the manufacturer as "various".

Not necessarily a bad thing, there are thousands of uBitx's out there with a clone no-name Nano,
and the Nano is far more complicated than a PFET.

I've bought a bunch of stuff from Tayda at their alarmingly low prices, it all seems to work just fine.

Jerry, KE7ER


On Mon, Sep 5, 2022 at 11:41 AM, JerryP wrote:

If you're looking for a P-Channel MOSFET for a power switch then this may be able to use a IRF5305 - TO-220, 55V, 31A, 0.06Ohm RDS On @$0.78 each:

Tayda has a $5.00 minimum order and their USPS shipment is 8-16 days and low cost.? While they may not have everything, it's very low priced and good quality.

?

toggle quoted messageShow quoted text

Farhan,

The Raspberry Pi OS has VNC built in.? That will open an X-window environment on any operating system.? Here is a link on how to set up to use VNC on a Raspberry Pi:


73
Evan
AC9TU

Thanks, Jerry.? ?Our County had spent > $100,000 on our group to provide 14 go-boxes with Public Service Motorolla truked?radios as well as far less expensive ham radios....because the hurricane shelters are steel reinforced concrete buildings (schools) and the police handhelds simply won't get out. ..? With hundreds of people cooped p in a shelter....the police Need To Reach Backup if there is a disturbance...hence our ham radio group.

We were terrified of destroying one of those radios because large storage batteries can ALWAYS be misconnected with ring connectors to their bolt-terminals....and hence this project.? ?We built a couple of dozen AT LEAST when mosfets were still easily obtainable.? ?Now it is harder to find.? ? You want to arrange for very low series resistance because it means much much less heat dissipation.? ? ? When the mosfets get hot, their series resistance goes up -- BAD CYCLE!!

I have this on my 7300 and still a spare or two sitting around, so one will go on the sBitx.? ? We have them on every key radio in our Emergency Operations Center.? ?People under STRESS will make mistakes.? ? You could probabaly?build the same circuit with an N channel....if yu are willing to break the ground wire, which we didn't want to do.

This is something that can be built MUCH EASIER with SMD's which?are much more readily available.? ?But I don't have that ability to fool with.? ?Others could do it much more easily than I.

Gordon

On Mon, Sep 5, 2022 at 12:53 PM Jerry Gaffke via <jgaffke=[email protected]> wrote:

Correction for the final sentence:
?If the user does NOT fuse the battery with a fast blow fuse
of the appropriate current rating, then a reversed battery can destroy the rig.


On Mon, Sep 5, 2022 at 09:20 AM, Jerry Gaffke wrote:

If the user does fuse the battery with a fast blow fuse
of the appropriate current rating, then a reversed battery can destroy the rig.

First, enable ssh on the sbitx.

1. From the main menu, Choose Preferences > Raspberry Pi Configuration

2. Click on the Interfaces tab

3. On the tab and enable SSH if not enabled, Click OK

4. From a terminal on the sbitx, type ifconfig and note the IP address of the sbitx. In my case it was 192.168.1.142

Second, from your linux laptop (yeah, it wont work with windoze, it might work on a mac, let us know)

1. Open a terminal window

2. Enable remote x clients to connect with the command "xhost?+" (without quotes)

3. Next, ssh to your sbitx with a special option like this :

 ssh [email protected] -X

Enter your password (by default it is hf12345).

4. Now you are connected to the sbitx. Go into the sbitx directory 

and execute the program like this:

cd sbitx
./sbitx

Correction for the final sentence:
?If the user does NOT fuse the battery with a fast blow fuse
of the appropriate current rating, then a reversed battery can destroy the rig.


On Mon, Sep 5, 2022 at 09:20 AM, Jerry Gaffke wrote:

If the user does fuse the battery with a fast blow fuse
of the appropriate current rating, then a reversed battery can destroy the rig.

Thanks for all the comments.

1.? It is difficult to fit ANYTIHNG inside an Icom 7300, so we build them externally for those and for $5000 police/fire transceivers.? ?Yes, it is better to install INSIDE...but sometimes you simply cannot.

2.? We previously used exactly what one commenter suggested -- the parallel reverse diode and series fuse.? ?Then one of my volunteers showed me a destroyed system where the diode didn't manage to blow the fuse in time for some fancy current measruing?gizmo.? ?Oops!? ?THat was the experience that got me working.

3.? Almost all of the P channel enhancement MOSFETS out there are very similar except for their series Rds-on? ? Most of them are quoted at a gate voltage of -10 (with reference to the source) and thus they are fairly interchangeable.? ?SOME (very few) have a protective zener built in to protect the vulnerable GATE but not very many, hence the zener built into the circuit in our simple (plagiarized) design.

4.? Yes, Max is right, these through-hole devices keep showing up--and then being made obsolete and disappearing.? ?However, the SMD versions are readily available.? ?I bought some -- yikes they are smaller than I like dealing with -- but then I found A NEW SUPPLIER of the automotive-market p-channel enhancements that had just what I was looking for and CHEAP.? ? I sent y'all the note quickly and haven't the time to find you that part instantly, but it (or the NEXT replacement) exists.? ?The worldwide governmental intrusion into markets has upset all manner of manufacturing and thus we have shortages of all kinds, but there is generally always something out there.? ??

5.? I can't remember, but I think I made the PCB availble as a Project on ? ? ?It isn't a great design.? ?It did however, allow a couple dozen to be made in our town and successfully.? ?Add solder or wires to the traces if you need a lot more current capability.? ?The MOSFETS used to be easily available so we put as many as 4 on there to handle 25 Amps.? ??

Perhaps I can find my notes and the latest enhancement mostfet out there that is available.? ?They all seem to have the same PINOUT as well, but of course, please check that.? ?In our design they lose less voltage THAN THE CONNECTORS!!!? ?And thus there is no need for heat sinks at all.? ?Amazing.? ?For a guy who started in vacujm tubes 12AX7 and 6146 and 811A....then had to learn bipolar transistors and their wierd?nonlinearities, to have some astonishingly low Rds-on in a MOSFET as a near perfect "switch" (at dc) is just amazing.? ??

Happy homebrewing!

73

Gordon KX4Z

On Mon, Sep 5, 2022 at 1:42 AM Max via <kg4pid=[email protected]> wrote:

Good luck finding the mosfet! The part has been superseded (change the last digit in the p/n from a 1 to a 2) but I couldn't find them anywhere. Mouser shows a lead time of 52 weeks which basically means they don't know when they will have them.

Max

On Sunday, September 4, 2022, 10:59:06 PM CDT, otalado <s53c.lado@...> wrote:

Hi, Gordon
while it is true that just showing a diode into the power supply line is cheap & quick, the solution you suggested is, without doubt, a lot better. In fact, I'll order (or produce) some PCB for the protector. Yet I strongly believe that such protection should always be built inside the box that needs protection!