Re: sBitx antenna-first warning
Scot, You have to build a resistive bridge like this :
Here, each of the 50 ohm resistors should be able to dissipate 10 watts. So, you make a 10 watt resistor by paralleling 10 resistors of 470 ohms each.? - f
Hi Ashhar,
I¡¯m a bit confused.? I get paralleling ten 470 ohm resistors but I¡¯m am uncertain how to use it.? How do you connect this arrangement (three legs) to protect the finals?? Is it in series with the antenna?? Can you sketch to wiring?
Thanks in advance, Scott
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Re: sBitx antenna-first warning
Hi Ashhar,
I¡¯m a bit confused. ?I get paralleling ten 470 ohm resistors but I¡¯m am uncertain how to use it. ?How do you connect this arrangement (three legs) to protect the finals? ?Is it in series with the antenna? ?Can you sketch to wiring?
Thanks in advance, Scott
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Re: A short video of sBitx working
I understand the need for a low pass filter. That is needed for the IC 7300 also which I built a low pass filter for it which was easy enough. It produces real nice harmonic spurs right through the AM? broadcast band without one, and gives a normal watt meter fits because one cannot tell where the rf is getting produced is in the electromagnetic spectrum. It also causes an swr meter on the radio to read incorrectly since the reflected spurs power causes the rf foldback to activate and cut the transmit power way down.
the rf tranformer in the sBitx has me wondering... is the what would pass for an output matching network in the PA, that is being refered to ?
thanks
Alan
On Tue, Aug 2, 2022, 6:09 PM Ashhar Farhan < farhanbox@...> wrote: The spec sheet is on? You could transmit on 630 khz. I am not sure if the PA transformer inductance will be enough that low.? The exciter will work right down to 10 KHz or so.
On Wed, Aug 3, 2022, 3:02 AM Alan Cooper < cqw7aln@...> wrote: Ashhar and group,
is there a manual or something resembling a spec sheet on the sBitx available anywhere?
I am trying to figure out if it will operate down below the AM Broadcast band,? there is a lot of Ft8 used on our 630Meter band on 474 khz.
Thanks for any info or input
Alan w7aln
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Re: Postman came with a box from hfsignals
I received notification from DHL today with delivery scheduled for Monday (not bad since I am in Ireland) , obviously the basic kit has started to ship, will look forward to much experimenting with this :)
On Tue, 2 Aug 2022 at 23:20, Shirley Dulcey KE1L < mark@...> wrote: Still waiting for my shipping notification. I've got one coming without the display and Pi.
?got #26!!!!? ?You beat me!!! but i still feel HONORED.? ?Gotta find a power connector and wire it all up.? Should have a logitech mouse/keyboard wireless in the car.? ?Tons of MEETING this week, but nice to have gotten this.? ?It came VERY NICELY PACKED.? ? My neighbor has theXiegu.....each has its points but this is a LARGE milestone in ham radio history, another one due to Ashhar!? (on the left is one of my primitive homebrew "go-boxes" for portable emergency deployments.
Gordon KX4Z
 
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The potentiometers has minimum at the "right" place. Lowest at anticlockwise position and max at clockwise position. Just like a volume pot.
oz9ny, niels
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Re: sBitx antenna-first warning
Many recommend tuning at a lower power. This risky as well. That is because at lower power, the output impedance of the PA will be different. Once you are tuned at QRP level, increasing the power will result in a mismatch again!? - f
Unfortunatel, no. The sbitx has no way to check the swr (yet).? Even if it had, as we are dealing with very high power, fiddling with the tuner for 15-20 seconds with large mismatch will send all the 40 watts back into the PA, destroying it. What will work is a resistive bridge. This will dissipate most of the power in big resistors until you are tuned up.? You can paraellel up ten x 470 ohm resistors of 1 watt to make each of the three legs of the resistive divider of the swr bridge. A DPDT switch can bypass it once you are all tuned up.
On Wed, Aug 3, 2022, 12:21 PM Trevor Stone < tstone@...> wrote: In the operating manual I see the following warning:
```
# 1. Connect the Antenna first!
The antenna jack on the back must always be connected to a properly
matched antenna with an SWR of less than 2 on the frequencies you intend
to transmit on. This is a recommendation for all amateur wireless radios
but more specifically the sBitx. The sBitx can put out upto 50 watts of
power and if the antenna does not match, it can damage the power
amplifier transistors instantaneously.
```
Does the sBitx have the ability to tune or check the SWR without
damaging itself, or does one need to use an antenna analyzer before
using the radio?
I ask because most of my operation is portable, so my SWR changes every
time I set up my station.? SWR can be high even for an antenna of the
right length if it's deployed in a compromised position or if I made an
error during setup (like last month when I forgot to attach
counterpoises to an end-fed antenna :-)
Thanks,
Trevor KF0FTJ
--
=-=-=-= Trevor Stone -=- [Flwyd] -=- <tstone @ > =-=-=-=
Computer science, eclectic philosophy, games, wits, esoterics, odd hats
? ? ? ? ? ?Thou brazen boil-brained malt-worm!
{embrace society}? ? ? ? ? ? ? ? ? ? ? ? ? POLAROID does it in seconds.
Calvin: The world is a complicated place, Hobbes.? Hobbes: Whenever it
seems that way, I take a nap in a tree and wait for dinner.
|
Re: sBitx antenna-first warning
Unfortunatel, no. The sbitx has no way to check the swr (yet).? Even if it had, as we are dealing with very high power, fiddling with the tuner for 15-20 seconds with large mismatch will send all the 40 watts back into the PA, destroying it. What will work is a resistive bridge. This will dissipate most of the power in big resistors until you are tuned up.? You can paraellel up ten x 470 ohm resistors of 1 watt to make each of the three legs of the resistive divider of the swr bridge. A DPDT switch can bypass it once you are all tuned up.
On Wed, Aug 3, 2022, 12:21 PM Trevor Stone < tstone@...> wrote: In the operating manual I see the following warning:
```
# 1. Connect the Antenna first!
The antenna jack on the back must always be connected to a properly
matched antenna with an SWR of less than 2 on the frequencies you intend
to transmit on. This is a recommendation for all amateur wireless radios
but more specifically the sBitx. The sBitx can put out upto 50 watts of
power and if the antenna does not match, it can damage the power
amplifier transistors instantaneously.
```
Does the sBitx have the ability to tune or check the SWR without
damaging itself, or does one need to use an antenna analyzer before
using the radio?
I ask because most of my operation is portable, so my SWR changes every
time I set up my station.? SWR can be high even for an antenna of the
right length if it's deployed in a compromised position or if I made an
error during setup (like last month when I forgot to attach
counterpoises to an end-fed antenna :-)
Thanks,
Trevor KF0FTJ
--
=-=-=-= Trevor Stone -=- [Flwyd] -=- <tstone @ > =-=-=-=
Computer science, eclectic philosophy, games, wits, esoterics, odd hats
? ? ? ? ? ?Thou brazen boil-brained malt-worm!
{embrace society}? ? ? ? ? ? ? ? ? ? ? ? ? POLAROID does it in seconds.
Calvin: The world is a complicated place, Hobbes.? Hobbes: Whenever it
seems that way, I take a nap in a tree and wait for dinner.
|
sBitx antenna-first warning
In the operating manual I see the following warning:
```
# 1. Connect the Antenna first!
The antenna jack on the back must always be connected to a properly matched antenna with an SWR of less than 2 on the frequencies you intend to transmit on. This is a recommendation for all amateur wireless radios but more specifically the sBitx. The sBitx can put out upto 50 watts of power and if the antenna does not match, it can damage the power amplifier transistors instantaneously.
```
Does the sBitx have the ability to tune or check the SWR without damaging itself, or does one need to use an antenna analyzer before using the radio?
I ask because most of my operation is portable, so my SWR changes every time I set up my station. SWR can be high even for an antenna of the right length if it's deployed in a compromised position or if I made an error during setup (like last month when I forgot to attach counterpoises to an end-fed antenna :-)
Thanks,
Trevor KF0FTJ
--
=-=-=-= Trevor Stone -=- [Flwyd] -=- <tstone @ trevorstone.org> =-=-=-=
Computer science, eclectic philosophy, games, wits, esoterics, odd hats
Thou brazen boil-brained malt-worm!
{embrace society} POLAROID does it in seconds.
Calvin: The world is a complicated place, Hobbes. Hobbes: Whenever it
seems that way, I take a nap in a tree and wait for dinner.
|
sBitx Power Connector Size & Minimum Current
I was very excited to discover that my sBitx (serial #0013) was delivered a day earlier than expected. I've been excited about this radio for the last six months, so I'm very glad to have it in my hands. (Unfortunately I'm about to head out of town for several days so I'll need to wait a bit to play with it.)
A couple questions about the power supply for the assmbled unit:
#1: What are the outer and inner diameters of the barrel connector? I'd like to make a PowerPole adapter cable and I want to make sure I get the right barrel end.
I've got a white-tipped barrel connector that looks like it fits, which I think means it's 5.5mm outer diameter and 2.5m inner diameter, but I'd like to make sure (and I guess a 2.5mm ID would fit in the jack even if the pin is expecting a 2.1mm ID).
#2: What's the minimum current for the radio in RX only mode?
I see the operating manual says "You need a juicy power supply that can supply upto 10 Amps current between 12V and 13.8V for the sBitx to provide full power. If you intend to operate low power, you will at least need a 6A power supply." Unfortunately, my coaxial power supply says that it only puts out 5.5 amps at 12 volts. Can I at least use that to turn the sBitx on and get things set up? Would it be enough for a < 5W transmission?
Also curious if anyone has suggestions on where to get connectors and what to look for? I live in the U.S., but I don't think my local hardware stores have bare connectors like this and shipping on something that small seems like it could exceed the price of the part.
Thanks,
Trevor KF0FTJ
--
=-=-=-= Trevor Stone -=- [Flwyd] -=- <tstone @ trevorstone.org> =-=-=-=
Computer science, eclectic philosophy, games, wits, esoterics, odd hats
Thou sottish ill-breeding canker-blossom!
{embrace friendship} RADIOLOGISTS do it with high frequency.
The world is too big. It can go on longer than we can. -- XKD #1190
|
My $0.02 are to make the monitor case a cube with a beveled sloping front as to make it easier to view the monitor when they are on a table top.?
decorations: star wars or Star Trek spaceships !
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I have thought about that and I think that it is a good idea but it is outside of my skill set. I guess I'm going to let the kinks of the sBITX and then try to acquire one -- '72
Aaron K5ATG
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Re: Turn off WiFi on your sBitx
It is tough and frustrating to be an "early adopter". I thank you all for taking the plunge, Respect!
The joys of mass production and finding little bitty problems. ? ?We have the same thing in drug product production and vaccine production of course.... only when you make a lot of some thing do you start to find a little bitty unexpected issues.?
We have the incredible advantage of having Ashhar right on top of everything!! ? My first Heathkit had horrible key clicks and I think I spent a year shipping it back-and-forth Benton Harbor (from earning money vacuuming the house ) before I learned enough to fix it myself. ?
Gordon ? Bob, Thats the LM380 having some kind of oscillations. I will have a fix for the quickly. The sound goes away if you turn the wifi off. Right click on the wifi icon and select Wifi off. - f On Wed, Aug 3, 2022, 2:46 AM Bob Losee KO9V < Loseeunc@...> wrote: I¡¯m having the same sounds¡ anywhere from 4 to 8 sounds then a several second pause, then starts again. ? Changing audio level makes no difference. I¡¯ve never tried transmitting¡ just listened to WWV across town from me and it is a clean stable receiver.? Tried logging in to my wifi but I still have two red X characters over the wifi symbol Bob, KO9V, Serial Number 20 On Aug 1, 2022, at 1:57 PM, Niels Jalling <niels@...> wrote:
?When I powered up my new sBitx I heard repeating noise from the loudspeaker. I knew I had seen the problem mentioned somewhere.
Found it on youtube:
Follow the description to turn off the WiFi and the noise goes away.
73 de oz9ny, niels
|
Aaron - why not build the Pi & the uBit into a single unit,
something like the sBit?
Gerry Sherman
Sent by the Thunderbird
On 2022-08-03 01:41, Aaron K5ATG via
groups.io wrote:
toggle quoted message
Show quoted text
Ok fellow BITX'ers.
I have tried to make a larger case for my uBITX so that I can use
a 3.5 inch Nextion along with other add-ons. Since I have
destroyed several steel cases in attempting to make a uBITX case I
have given up on steel.?
Since I am a wood worker an a scroll saw artist I have decided to
make a wooden case and decorate it with scroll saw designs. I want
to use flashing painted black on the interior of the case. The
flashing will provide a good background in the scroll saw
decorations like the darker background in this plaque of Jesus
that I made:
I am not going to put a Jesus on my uBITX. I would like for you
guys to help me come up with designs for it. I am thinking of
possible schematics but don't know what schematics I should use.
Schematics of part of the uBITX? Other radio images will be
considered so I really would love to hear your ideas. I want it to
be one of a kind.?
Another thing I need your help on is the wood. I have it down to
oak. and eastern red cedar.?
I'm sure everyone here knows what oak looks like. Here is a
picture of eastern red cedar lumber:
It is a regional wood species?
I can make almost any design with my scroll saw. I am just really
bad on what designs I should use.?
Also besides my uBITX, I have a display from an old laptop. I got
a driver for it to use as a monitor for my Raspberry Pi 4. It is
just a bare display so I will make a case for it to match my uBITX
since uBITX is always hooked up to my Raspberry Pi anyway.?
So please help me with ideas.?
--
'72
Aaron K5ATG
|
Re: Turn off WiFi on your sBitx
The joys of mass production and finding little bitty problems. ? ?We have the same thing in drug product production and vaccine production of course.... only when you make a lot of some thing do you start to find a little bitty unexpected issues.?
We have the incredible advantage of having Ashhar right on top of everything!! ? My first Heathkit had horrible key clicks and I think I spent a year shipping it back-and-forth Benton Harbor (from earning money vacuuming the house ) before I learned enough to fix it myself. ?
Gordon
toggle quoted message
Show quoted text
On Aug 2, 2022, at 21:15, Ashhar Farhan <farhanbox@...> wrote:
? Bob, Thats the LM380 having some kind of oscillations. I will have a fix for the quickly. The sound goes away if you turn the wifi off. Right click on the wifi icon and select Wifi off. - f On Wed, Aug 3, 2022, 2:46 AM Bob Losee KO9V < Loseeunc@...> wrote: I¡¯m having the same sounds¡ anywhere from 4 to 8 sounds then a several second pause, then starts again. ? Changing audio level makes no difference. I¡¯ve never tried transmitting¡ just listened to WWV across town from me and it is a clean stable receiver.? Tried logging in to my wifi but I still have two red X characters over the wifi symbol Bob, KO9V, Serial Number 20 On Aug 1, 2022, at 1:57 PM, Niels Jalling <niels@...> wrote:
?When I powered up my new sBitx I heard repeating noise from the loudspeaker. I knew I had seen the problem mentioned somewhere.
Found it on youtube:
Follow the description to turn off the WiFi and the noise goes away.
73 de oz9ny, niels
|
Ok fellow BITX'ers. I have tried to make a larger case for my uBITX so that I can use a 3.5 inch Nextion along with other add-ons. Since I have destroyed several steel cases in attempting to make a uBITX case I have given up on steel.? Since I am a wood worker an a scroll saw artist I have decided to make a wooden case and decorate it with scroll saw designs. I want to use flashing painted black on the interior of the case. The flashing will provide a good background in the scroll saw decorations like the darker background in this plaque of Jesus that I made:  I am not going to put a Jesus on my uBITX. I would like for you guys to help me come up with designs for it. I am thinking of possible schematics but don't know what schematics I should use. Schematics of part of the uBITX? Other radio images will be considered so I really would love to hear your ideas. I want it to be one of a kind.? Another thing I need your help on is the wood. I have it down to oak. and eastern red cedar.? I'm sure everyone here knows what oak looks like. Here is a picture of eastern red cedar lumber:  It is a regional wood species? I can make almost any design with my scroll saw. I am just really bad on what designs I should use.? Also besides my uBITX, I have a display from an old laptop. I got a driver for it to use as a monitor for my Raspberry Pi 4. It is just a bare display so I will make a case for it to match my uBITX since uBITX is always hooked up to my Raspberry Pi anyway.? So please help me with ideas.? -- '72
Aaron K5ATG
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Re: Turn off WiFi on your sBitx
Bob, Thats the LM380 having some kind of oscillations. I will have a fix for the quickly. The sound goes away if you turn the wifi off. Right click on the wifi icon and select Wifi off. - f
On Wed, Aug 3, 2022, 2:46 AM Bob Losee KO9V < Loseeunc@...> wrote: I¡¯m having the same sounds¡ anywhere from 4 to 8 sounds then a several second pause, then starts again. ? Changing audio level makes no difference. I¡¯ve never tried transmitting¡ just listened to WWV across town from me and it is a clean stable receiver.? Tried logging in to my wifi but I still have two red X characters over the wifi symbol Bob, KO9V, Serial Number 20 On Aug 1, 2022, at 1:57 PM, Niels Jalling <niels@...> wrote:
?When I powered up my new sBitx I heard repeating noise from the loudspeaker. I knew I had seen the problem mentioned somewhere.
Found it on youtube:
Follow the description to turn off the WiFi and the noise goes away.
73 de oz9ny, niels
|
Re: A short video of sBitx working
The spec sheet is on? You could transmit on 630 khz. I am not sure if the PA transformer inductance will be enough that low.? The exciter will work right down to 10 KHz or so.
On Wed, Aug 3, 2022, 3:02 AM Alan Cooper < cqw7aln@...> wrote: Ashhar and group,
is there a manual or something resembling a spec sheet on the sBitx available anywhere?
I am trying to figure out if it will operate down below the AM Broadcast band,? there is a lot of Ft8 used on our 630Meter band on 474 khz.
Thanks for any info or input
Alan w7aln
|
The pots to set the IRF510 bias on the uBitx and Bitx40 were backwards
from what most people would expect.
My best guess is that the sBitx follows this unfortunate tradition
since pin 3 of RV1 and RV3 is grounded, same as it was on RV2 and RV3 of the uBitx.
And it looks like the same Kicad symbol and blue physical part was used,
so fully clockwise for minimum bias voltage to the gates of the final is most likely.
I suggest you measure from the middle pin of RV1 to ground
with the power off using an ohmmeter, should show zero ohms
when gate bias is set to a minimum.
Jerry, KE7ER
toggle quoted message
Show quoted text
On Tue, Aug 2, 2022 at 08:55 AM, Niels Jalling wrote:
I have just burnet the PA IRFZ24's.
Where Is zero for the DRIVE_BIAS POT and PA_BIAS POT?
Is it where you expect it at anti clock wise end.
73 de oz9ny, niels
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On 8/2/2022 19:38, Rolan Rister wrote: <>
Looks like ring is PTT, tip is microphone audio. Thanks much. Planning on reworking a digital mode interface to use with it. -- Tom Sevart N2UHC St. Paul, KS
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Looks like ring is PTT, tip is microphone audio.
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Thomas White AD6TW
Aaron K5ATG