Re: uBitxV6 -by transmitting resets-
Hi Ted,
?
One thing to remember is the difference in display current requirements.? The V6 is a touch screen with graphics capability, while the V5 is a 16x2 text display.?
?
Also, note that the v6 Raduino already has a heatsink on it.
?
I would be careful with the 10-ohm resistor.? If you use that on a v6, you may drop below the minimum input voltage for the 7805 (approx 7 volts).? This will depend on the supplied voltage.? Assume a 10-ohm resistor will drop the voltage by 10 volts at peak load.? A better value for 14 volts would be a 6 or 7-ohm resistor.? The resistor should have a 10-watt rating.? A more reasonable choice would be a 5-watt 5-ohm resistor or five 1-amp diodes.
?
73
Evan
AC9TU
|
Re: uBitxV6 -by transmitting resets-
I've been shouted down about using diodes in this way on other forums, but I still thing it is an easy solution to a potential problem, and it has the added advantage of preventing reverse polarity accidents in some situations.
Gordon and Ted are right; inline diodes do not produce noise unlike some other regulators. They are also ham-price-friendly AKA CHEAP! Daisy chain 5 and you are placing ~10-11 volts instead of 13.8 on the front end of that 7805, so it only has to deal with 60-70% (math done in my head) of the heat dissipation for a given current.
73 de Lee KX4TT
On Tuesday, March 4, 2025 at 12:17:08 PM EST, Ted via groups.io <k3rta@...> wrote:
Hello, Pieter.
?
I gather from commentary so far, that your 7805 is overheating from having to regulate down from 13.8 (down to 5v).? I don't have that problem and it may simply be that I have a heat sink on that regulator but I also have (what I believe is) a 10-ohm resistor in line with the B+ supply to the 7805. Thus, the ideas presented above to add diodes to the input of this regulator has merit. Dropping about 0.6v X 3 might help your regulator work less than it done at present.? As diodes are fairly cheap, use 4 if you like, even 5.?
?
I've got a few of the other form of voltage regulators and have yet to substitute one for the 7805 - though I've experimented for the radio supply itself and noticed no added RF noise.?
?
?
72,
?
Ted
K3RTA
?
?
|
Re: uBitxV6 -by transmitting resets-
Hello, Pieter.
?
I'm new to this discussion but not new to the MicroBITX.? I run a version 5 radio on a 16v internal battery bank - two sets of four, with a battery-management board in place.? This yields over 15 watts output on 40m CW, around 10w on 20m & 15m, and about 5w on 12/10m.
?
I gather from commentary so far, that your 7805 is overheating from having to regulate down from 13.8 (down to 5v).? I don't have that problem and it may simply be that I have a heat sink on that regulator but I also have (what I believe is) a 10-ohm resistor in line with the B+ supply to the 7805. Thus, the ideas presented above to add diodes to the input of this regulator has merit. Dropping about 0.6v X 3 might help your regulator work less than it done at present.? As diodes are fairly cheap, use 4 if you like, even 5.?
?
I've got a few of the and have yet to substitute one for the 7805 - though I've experimented for the radio supply itself and noticed no added RF noise.?
?
?
72,
?
Ted
K3RTA
?
?
?
?
?
?
|
Tom,
?
I've sent you an email.? I'm responding here so other people don't argue with my place in line.
?
Cheers,
Harris Butler, NN0Y
|
|
|
|
|
May i ask what resolved the low output on 20m what was it before and where is it now. Mine is also sluggish there at 13 watts while 40 is 22 watts. I expect it to be lower but??
Thank you?
--
Patrick?
|
?
Selling my sBitx V2 serial no. 0251. I assembled it, made a few ft8 and cw contacts, updated to 64-bit, #D printed a cover that allows for connection of mini HDMI cable to PI for extended display. Works great plugged into a 48" 1080P display (see pics on QRZ swapmeet). Was fun to play with, but now just sits.? Still has protective film on the screen and I installed Anderson power poles on the power cable. Includes everything that came in the box.
- Fully assembled and tested sBitx-v2 with the Raspberry 4 updated to 64-bit sBitx image.
- 7 inch capactive display
- 32 GB SD card installed with software
- XT60 power cable with power poles.
- Microphone
$275 shipped USPS Ground to lower 48 Cash in person or PayPal. ?
Also posted on QRZ, search my callsign for pictures.
|
Absolutely! I definitely am down for a kit. I'll reach out Thurs. I'm glad you caught me on this. I love Farhans ideas, But like you mentioned, it makes no sense to me why you wouldn't go the route of a MUCH needed sturdier PA section.
73
K8MCB
toggle quoted message
Show quoted text
Well thats the very reason i designed that little gem. ?It works without gain sag to 54 MHz… and you can short out or open the output 24/7 with no issues other than generating some heat. ?I gave Farhan a free board last FDIM but
he seemingly isnt interested in such robust designs. ?In any case just email me Thursday if you want a semi-kit (returning from my contest station J62K currently).
Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ
?
Owner - Operator
Big Signal Ranch – K9ZC
Staunton, Illinois
?
Owner – Operator
Villa Grand Piton - J68HZ
Soufriere, St. Lucia W.I.
Rent it: www.VillaGrandPiton.com
email:?
bill@...
?
On Mar 3, 2025, at 8:02?PM, Michael Bales via groups.io <mikebales73@...> wrote:
?
Yes, I understand trying to keep the cost of components down, but after further research, and my own experiences with a few bitx products, why keep chasing down a design around a MOSFET not intended for RF and spend a few more dollars on something like the
RD16HFF1, and be rid of the seemingly constant PA problems....
Yeah i bobbed the PAs out of all my BIT radios and use that 20W pa. ? Its got great specs and the semi-kit only cost about $20 plus shipping.?
Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ
?
Owner - Operator
Big Signal Ranch – K9ZC
Staunton, Illinois
?
Owner – Operator
Villa Grand Piton - J68HZ
Soufriere, St. Lucia W.I.
Rent it: www.VillaGrandPiton.com
email:?
bill@...
?
On Mar 3, 2025, at 11:37?AM, Evan Hand via groups.io <elhandjr@...> wrote:
?
Hi Mike,
?
Have you looked at the K9HZ amp that is part of the T41 project?
?
or
?
This might meet your needs.
?
You could couple it with the LPF and T/R switch the sBitx uses.
?
73
Evan
AC9TU
--
Mike - K8MCB?
-- Mike - K8MCB?
|
Well thats the very reason i designed that little gem. ?It works without gain sag to 54 MHz… and you can short out or open the output 24/7 with no issues other than generating some heat. ?I gave Farhan a free board last FDIM but he seemingly isnt interested in such robust designs. ?In any case just email me Thursday if you want a semi-kit (returning from my contest station J62K currently).
Dr.?William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ ? Owner - Operator Big Signal Ranch – K9ZC Staunton, Illinois ? Owner – Operator Villa Grand Piton - J68HZ Soufriere, St. Lucia W.I. Rent it: www.VillaGrandPiton.com
email:??bill@... ?
toggle quoted message
Show quoted text
On Mar 3, 2025, at 8:02?PM, Michael Bales via groups.io <mikebales73@...> wrote:
?
Yes, I understand trying to keep the cost of components down, but after further research, and my own experiences with a few bitx products, why keep chasing down a design around a MOSFET not intended for RF and spend a few more dollars on something like the
RD16HFF1, and be rid of the seemingly constant PA problems....
Yeah i bobbed the PAs out of all my BIT radios and use that 20W pa. ? Its got great specs and the semi-kit only cost about $20 plus shipping.?
Dr.?William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ
?
Owner - Operator
Big Signal Ranch – K9ZC
Staunton, Illinois
?
Owner – Operator
Villa Grand Piton - J68HZ
Soufriere, St. Lucia W.I.
Rent it: www.VillaGrandPiton.com
email:??bill@...
?
On Mar 3, 2025, at 11:37?AM, Evan Hand via groups.io <elhandjr@...> wrote:
?
Hi Mike,
?
Have you looked at the K9HZ amp that is part of the T41 project?
?
or
?
This might meet your needs.
?
You could couple it with the LPF and T/R switch the sBitx uses.
?
73
Evan
AC9TU
-- Mike - K8MCB?
|
The diode solution won’t make any noise either! Those switching systems might make noise!!?
toggle quoted message
Show quoted text
On Mar 3, 2025, at 20:14, WK4DS via groups.io <georgiaphotog@...> wrote:
? Simpler and less efficient?was would be to solder some 6A10 rectifier diodes in series till you get the voltage down to what you need. I have used this in the past and it works. I am sure there are better options out there, but if you have diodes and time, this will work. A LM317 and a simple circuit around?it would probably be better, but most likey?cost more too. A bag of the 6A10 diodes are one 6 or 7$ on Amazon...
David
Hello, we haven't received any zBitx yet and I'm already thinking about modifying something.
I don't really like the fact that it goes to a maximum of 9v, and I would like to know how to modify the device to make it work at 13,8vdc like the rest of the radio devices that most of us have.
I've looked at some components in the sBitx schematic and I think they are basically the same. So, what changes? I don't want to get more power (it wouldn't be bad to get 20w ;-) ) but I want to be able to have access to all the power sources I have.
thanks... I'm anxiously awaiting my shipment from India...
Jordi
From Catalonia.
|
Simpler and less efficient?was would be to solder some 6A10 rectifier diodes in series till you get the voltage down to what you need. I have used this in the past and it works. I am sure there are better options out there, but if you have diodes and time, this will work. A LM317 and a simple circuit around?it would probably be better, but most likey?cost more too. A bag of the 6A10 diodes are one 6 or 7$ on Amazon...
David
Hello, we haven't received any zBitx yet and I'm already thinking about modifying something.
I don't really like the fact that it goes to a maximum of 9v, and I would like to know how to modify the device to make it work at 13,8vdc like the rest of the radio devices that most of us have.
I've looked at some components in the sBitx schematic and I think they are basically the same. So, what changes? I don't want to get more power (it wouldn't be bad to get 20w ;-) ) but I want to be able to have access to all the power sources I have.
thanks... I'm anxiously awaiting my shipment from India...
Jordi
From Catalonia.
|
Yes, I understand trying to keep the cost of components down, but after further research, and my own experiences with a few bitx products, why keep chasing down a design around a MOSFET not intended for RF and spend a few more dollars on something like the
RD16HFF1, and be rid of the seemingly constant PA problems....
toggle quoted message
Show quoted text
Yeah i bobbed the PAs out of all my BIT radios and use that 20W pa. ? Its got great specs and the semi-kit only cost about $20 plus shipping.?
Dr.?William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ
?
Owner - Operator
Big Signal Ranch – K9ZC
Staunton, Illinois
?
Owner – Operator
Villa Grand Piton - J68HZ
Soufriere, St. Lucia W.I.
Rent it: www.VillaGrandPiton.com
email:??bill@...
?
On Mar 3, 2025, at 11:37?AM, Evan Hand via groups.io <elhandjr@...> wrote:
?
Hi Mike,
?
Have you looked at the K9HZ amp that is part of the T41 project?
?
or
?
This might meet your needs.
?
You could couple it with the LPF and T/R switch the sBitx uses.
?
73
Evan
AC9TU
-- Mike - K8MCB?
|
Amazon and AliExpress sell sealed buck boost regulators from 3 Amps to 30 Amps from about $5 to $50. They are pretty much bulletproof. Output voltage is chosen by the unit selected and input is from about 5 to 50 volts. Run your zBitx from a solar panel!
Jay NM2M?
I think you'd be best served by using a regulator to turn 13.8v into 9v, rather than trying to redesign the radio to natively run on 13.8v. I imagine a suitable circuit could be installed in the 18650 battery case on the side of the zBitx case, rather than putting such a heat source inside the case.
?
Personally, I plan to use the battery powered option, but I do understand the desire to operate from a standardized 13.8v power source...
?
Ken, N2VIP
|
You might want to look at some of the DROK buck converters.? I
think they have one that will do what you want, & they are
very power efficient.
Gerry Sherman
Sent by the Windows 11 Thunderbird
On 2025-03-03 22:57, Ken N2VIP wrote:
toggle quoted message
Show quoted text
I think you'd be best served by using a regulator to turn
13.8v into 9v, rather than trying to redesign the radio to
natively run on 13.8v. I imagine a suitable circuit could be
installed in the 18650 battery case on the side of the zBitx
case, rather than putting such a heat source inside the case.
?
Personally, I plan to use the battery powered option, but I
do understand the desire to operate from a standardized 13.8v
power source...
?
Ken, N2VIP
|
I think you'd be best served by using a regulator to turn 13.8v into 9v, rather than trying to redesign the radio to natively run on 13.8v. I imagine a suitable circuit could be installed in the 18650 battery case on the side of the zBitx case, rather than putting such a heat source inside the case.
?
Personally, I plan to use the battery powered option, but I do understand the desire to operate from a standardized 13.8v power source...
?
Ken, N2VIP
|
Hello, we haven't received any zBitx yet and I'm already thinking about modifying something.
I don't really like the fact that it goes to a maximum of 9v, and I would like to know how to modify the device to make it work at 13,8vdc like the rest of the radio devices that most of us have.
I've looked at some components in the sBitx schematic and I think they are basically the same. So, what changes? I don't want to get more power (it wouldn't be bad to get 20w ;-) ) but I want to be able to have access to all the power sources I have.
thanks... I'm anxiously awaiting my shipment from India...
Jordi
From Catalonia.
|
Okay, I'm interested. Where is the site to order from?
--
Mike - K8MCB?
|
This the complete Sbitx as built,? the only 2 changes are the upgrade of the Raspberry Pi 4 from 2GB memory to 4 GB memory and the master board was upgraded to a newer model to resolve the low power on 20 meters.? The mike, power cord with Anderson power poles,
and legs to support the Sbitx ?at a good viewing angle.??
Tom Crowley KT4XN
toggle quoted message
Show quoted text
Hi Tom,
?
Is the case included?? Any other items that are included, like the mic and display?
?
73
Evan
AC9TU
|
|
|
Lee
Ted
K9HZ
WK4DS
EB3AM Jordi
