Got my notification today.? Can't wait . . . de nf5k, jim
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Re: RF power chain mods and improvements..
Thanks Allison for this information I have noticed similar heating of the driver transistors and also T11. I see a reduction of output somewhat on the order of 10 to 20 percent with increasing heat.? I¡¯m going to wind a new T11 using a binocular core the single core toroid is inadequate for the power levels we are seeing. I¡¯m running my UBITX at 13.5 volts but want to build another one in a grab and go case with batteries like you had mentioned.? Just to let you know what I¡¯ve done is bypass all driver emitters with 330pf caps and added 30uh inductors inline with the 1k bias resistors. I also added a 20pf across the T11 primary this increased output and flattened out the response some at the higher frequencies. I¡¯m seeing a minimum of 4 watts on 10 meters with RV1 adjusted to 14 watts on 40 meters.?
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On May 19, 2018, at 11:03, ajparent1/KB1GMX < kb1gmx@...> wrote: First all changes are on a production uBitx not an older brassboard model.
The first findings are not about power out, I haven't fully tested.
What I did find is at 13.8V all on the 2n3904s in the power chain run very hot
with no signal.? How hot 125-130 degrees.? Measurements had the first Q90
running at 38ma and for a low level sage thats very high and for a 3904 its
near excessive.
Why is that problem?? THe bata sheet says that as we increase the device
current the HFE goes down and leads to reduced gain and, also lots of heat.
Current solution was to increase the bias resistor R81 from 1K to 2.5K but as two parts
?Its 1K +1.5K and the 1.5K gets a .1uf capacitor across that so the stage gain is maintained.
This lowers the current to about 20MA (19.6 actual).? FYI that means the device is now
dissipating 230mW of power where before it was 390mW.? The device max is 500mw
and I"ve found when you get close to that they fail.
One to the drivers.? Another noted he tried 2n2219s and they get warm.? Likely?
it was the bias level alone causing that.? ?The current?devices in mine are 3904
and they are hot at 130-135F.? Again the bias is wrong?(does not allow for
devices with higher than average HFE) and the device current is much too
high In a class AB push pull the current need not be this high.? The same
technique? of splitting the bias value so the 1K is unbypassed is used and
the same values 1k+1.5K (1.5k bypassed) are more suitable and result in a
16ma standing current per device.??
Much of this is the result of transistors being anything but uniform.? HFE
variations? for 2n3904 is around 50 to 300? and varies with device current.
This is typical.? But that also is variable across vendors.
Those changes alone have had no testing for power out at 20M and 10M yet.
That will be? the next step.? Right now I was trying to get the devices in the
range where they should behave as good as they can.
Allison
?
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As promised, I recv'd my shipping notification today.??
I AM SO EXCITED!
73 K5KDT Kevin
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Re: RF power chain mods and improvements..
Farhan,
its a stepwise process and will take a bit of testing.? ?Whats good is In the local club there are three
other uBitx radios.? This? way the changes have a test n greater than 1.
Allison
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Re: Help, can't change frequencies on uBitx
Yes, it responds to the push button depression just fine...
--
72 and God bless
KD4EPG
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Re: Help, can't change frequencies on uBitx
Yes it is...
--
72 and God bless
KD4EPG
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-- yes, I understand that..that I how I do it..
72 and God bless
KD4EPG
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Re: CONTEST!!!! New Board Naming Contest
#ubitx
Don't forget, the board naming contest (see w0eb.com for full details) ends at 23:59 UTC tomorrow.? If you haven't entered yet and want to, DO NOT post the name you submit on this reflector or it will be disqualified - the email address for entering is defined earlier in this thread and there is also a direct email link on in the contest information.
Winner will receive one of the new boards with a kit of all parts (less the Teensy 3.6 MPU).
Good luck,
Jim - W0EB
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Re: RF power chain mods and improvements..
Allison, We will be keenly following your experiments with the power chain. I will mod my ugly build to replicate your experiments. I suspect that lower standing current in the push pull drivers would be alright.? - f - f
On Sat, 19 May 2018, 20:33 ajparent1/KB1GMX, < kb1gmx@...> wrote: First all changes are on a production uBitx not an older brassboard model.
The first findings are not about power out, I haven't fully tested.
What I did find is at 13.8V all on the 2n3904s in the power chain run very hot
with no signal.? How hot 125-130 degrees.? Measurements had the first Q90
running at 38ma and for a low level sage thats very high and for a 3904 its
near excessive.
Why is that problem?? THe bata sheet says that as we increase the device
current the HFE goes down and leads to reduced gain and, also lots of heat.
Current solution was to increase the bias resistor R81 from 1K to 2.5K but as two parts
?Its 1K +1.5K and the 1.5K gets a .1uf capacitor across that so the stage gain is maintained.
This lowers the current to about 20MA (19.6 actual).? FYI that means the device is now
dissipating 230mW of power where before it was 390mW.? The device max is 500mw
and I"ve found when you get close to that they fail.
One to the drivers.? Another noted he tried 2n2219s and they get warm.? Likely?
it was the bias level alone causing that.? ?The current?devices in mine are 3904
and they are hot at 130-135F.? Again the bias is wrong?(does not allow for
devices with higher than average HFE) and the device current is much too
high In a class AB push pull the current need not be this high.? The same
technique? of splitting the bias value so the 1K is unbypassed is used and
the same values 1k+1.5K (1.5k bypassed) are more suitable and result in a
16ma standing current per device.??
Much of this is the result of transistors being anything but uniform.? HFE
variations? for 2n3904 is around 50 to 300? and varies with device current.
This is typical.? But that also is variable across vendors.
Those changes alone have had no testing for power out at 20M and 10M yet.
That will be? the next step.? Right now I was trying to get the devices in the
range where they should behave as good as they can.
Allison
?
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Re: Using IRF530 outputs and 2N3553 drivers in ubitx
After I wrote the last email, I realized the cascode configuration is much better.
It needs 2 more FETs but you drive the gate of the first one, and it provides the drive to the second one and the second one's gate is AC ground. I can't do it now, but I will see if I can find time to design one next week.
If you wanted to do this with uBitx, remove the exiting output xformer, add 2 IRF530 and a higher voltage supply, with a new output transformer. Should get up to 50W easily without changing the driver.
Howard
Quoting "Rahul Srivastava via Groups.Io" <vu3wjm@...>:
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Thanks..!!? Alison for the detailed analysis. Just to scratch the itch maybe I will hook up one in mid air with a 25:1 transformer at input and standard bifilar on drain.?
I once made 3x3 pushpull on IRF510 running at 30V for? 27.120Mhz ISM band freq got pretty decent 150W output. Input was on binocular core and output on stacked Mix 6 toroids.?
73
Rahul VU3WJM
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Re: RF power chain mods and improvements..
First all changes are on a production uBitx not an older brassboard model.
The first findings are not about power out, I haven't fully tested.
What I did find is at 13.8V all on the 2n3904s in the power chain run very hot
with no signal.? How hot 125-130 degrees.? Measurements had the first Q90
running at 38ma and for a low level sage thats very high and for a 3904 its
near excessive.
Why is that problem?? THe bata sheet says that as we increase the device
current the HFE goes down and leads to reduced gain and, also lots of heat.
Current solution was to increase the bias resistor R81 from 1K to 2.5K but as two parts
?Its 1K +1.5K and the 1.5K gets a .1uf capacitor across that so the stage gain is maintained.
This lowers the current to about 20MA (19.6 actual).? FYI that means the device is now
dissipating 230mW of power where before it was 390mW.? The device max is 500mw
and I"ve found when you get close to that they fail.
One to the drivers.? Another noted he tried 2n2219s and they get warm.? Likely?
it was the bias level alone causing that.? ?The current?devices in mine are 3904
and they are hot at 130-135F.? Again the bias is wrong?(does not allow for
devices with higher than average HFE) and the device current is much too
high In a class AB push pull the current need not be this high.? The same
technique? of splitting the bias value so the 1K is unbypassed is used and
the same values 1k+1.5K (1.5k bypassed) are more suitable and result in a
16ma standing current per device.??
Much of this is the result of transistors being anything but uniform.? HFE
variations? for 2n3904 is around 50 to 300? and varies with device current.
This is typical.? But that also is variable across vendors.
Those changes alone have had no testing for power out at 20M and 10M yet.
That will be? the next step.? Right now I was trying to get the devices in the
range where they should behave as good as they can.
Allison
?
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Hi,
Just completed my uBITZ and got it boxed. Still some finishing touches and I will post some pictures.
Switched it on and everything is performing as described with the supplied firmware.?
I do have the audio chip with the WX**** code but audio is good into either 8 ohm or 4 ohm speaker. It sounds to me better on the 8 ohm speaker.
The display brightness is very strong and I can only view the readings if I am looking down at about 45 degrees. The pot seems to be at the lowest point. I tried it the other way but the digits disappeared and the display
got brighter.
I have not seen any messages about the display. Only listening at present until I get the speaker installed. Not done any calibration yet but did check against my 10 MHz GPS standard and switching from LSB to??USB?couldn't
detect any difference.
Will keep checking and testing.
Peter Paul Fox G8HAV
Mid-Cheshire Amateur Radio Society
5 Llandovery Close
Winsford
Cheshire CW7 1NA?
Group Controller
Dane Valley?RAYNET?
Tel: 01606553401 (H)
Tel: 07919315547 (M)
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if the top line looks like a line of boxes try adjusting the contrast pot on the back of the raduino...
Allison
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RF power chain mods and improvements..
I'd like to consolidate discussion on changes and improvements to get uniform power out
here.
So it helps others please stay very close to the topic.? For example no discussion of external amps.
I will report my findings so far in the next post.
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Re: rough draft of how to connect BITX to PC for digital modes wiki
W7PEA the wiki page looks great.? I'll try to add some pictures and missing links.? I took the liberty of changing the title.? First I removed uBITX because this is not exclusive to the ?BITX.? It works for any BITX or really just about any transmitter.? Also, I took my call out of the title.? As much as it is appreciated, it is way, way more credit then I deserve.? All I did was compile things I found here and a few other sites and wrote up the notes I had in my head from melting it all together.? This is a community effort, I just type fast and posted it.
--
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Re: Should we adopt the KD8CEC firmware?
i suppose that we need to prevent TX enable in the Non-ham bands. while the Rx could still be useful for listening. ?
On Saturday 12 May 2018, 11:38:37 AM IST, Ashhar Farhan <farhanbox@...> wrote:
Peeps,
Given that Dr.Lee's software is now pretty stable from 1.06 onwards, what do you all say about using this as the 'shipped' firmware? I have some personal quirks that make me modify it for my personal use (ex: I prefere general coverage when changing the bands rather than steps to and from ham bands) but do we consider it to be usable and stable for our needs??
I resisted feature-ful software as the base because smaller code base makes it easier for people to get in and modify, there is space in the memory for modifications, etc.?
If there is a general consensus, then, we will customize it to the standard hardware, and start burning this into the next batch of ubitx.
Opinions, please.
- f
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It is only with a Nano that has been programmed with stock firmware (as they arrive from hfsignals)
that will have around 4 or 5v on those four pins.? A raw unprogrammed Nano will have those pins floating,
and they could measure anything between 0 and 5v.
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On Sat, May 19, 2018 at 06:20 am, Jerry Gaffke wrote:
Probably more like 4.5v if taking power from the USB host, no other connections to the Raduino Nano+display assembly.
All four pins on the right side of that connector (for ENCA, ENCB, FCTN and PTT) should be at 4.5v to ground.
If any of them are not up around 4.5v, power down and measure ohms from that pin to ground, I am very curious.
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Probably more like 4.5v if taking power from the USB host, no other connections to the Raduino Nano+display assembly.
All four pins on the right side of that connector (for ENCA, ENCB, FCTN and PTT) should be at 4.5v to ground.
If any of them are not up around 4.5v, power down and measure ohms from that pin to ground, I am very curious.
Jerry
?
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On Fri, May 18, 2018 at 10:49 pm, Mike aka KC2WVB wrote:
I have yet to perform the voltage test on the Nano. I ran out of steam after the 40 meter rig was completed but I will make the test tomorrow. Incidentally, should the reading across the two pins be spot on 5 volts or is there some leeway?
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Re: #bitx40 #bitx40help bitx 40 Amateur radio kits world wide kit questions.
#bitx40
#bitx40help
Sunil's got lots of cases to choose from, for both Bitx40 and uBitx:
? ??
Here's the "Universal Case Blue II for Bitx40":
? ??
Packing list shows "10k LIN Control x2" and a "Push to on switch x 1"
The front panel shots show main tuning, audio gain, and mike gain with matching knobs provided.
From that I'd guess he is supplying pots for mike gain and audio gain plus a power switch,
The audio gain with integrated switch from hfsignals is not used because the shaft is too small
for his matching knobs, it is replaced by one of the 10k pots plus the switch.
I assume the other 10k pot is for mike gain which is not a bad idea.
No additional parts for hacking in a mike gain, and perhaps no instructions for how to do so.
No indication of a third pot of 100k in Sunil's packing list.? Such a pot would work for main tuning,
but the 10k pot provided by hfsignals for this should be sufficient
since it has a standard 1/4" shaft on it.
Anybody else have one of these Version 2 Bitx40 enclosure kits?
Did you wind up with an extra 100k pot?
How did you wire up the mike gain pot?
I suggest you use the pots as I described above, so you may have a spare 100k pot from
Sunil and a spare audio pot from hfsignals.??
Wire it up as per the hfsignals webpage, leaving out the second 10k pot from Sunil for mike gain
till you have it working.
All vague conjecture, Sunil may check in here and give some real information on this.?
Jerry, KE7ER
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On Fri, May 18, 2018 at 11:50 pm, Ashhar Farhan wrote:
I am not sure that sunil sells kits for the bitx40. I know that he does sell ubitx kits.
?
- f
. . .
?
On Fri, May 18, 2018 at 12:26 PM, <ShahanStuart@...> wrote:
A little background
I was given a bitx 40 for a gift from my brother. I'm a tinckerer? by nature so this makes sense. However, electronics are kind of new to me.
Since this will be my first HF rig I opted to do a clean build. I ordered a model II case from amateur radio kits. The kit is cut to use a baofeng type ptt mic, the kit also has a gain control. It came with 10k pots x2, and a 100k pot. I. Not sure what pot goes where. I'm also not sure how to wire in the gain control. Can i get some guidance.?
Thanks for the help.
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Re: Ashhar Farhan Inducted into CQ Amateur Radio Hall of Fame
He brought Amateur radio in from the clutches of greed to those that need..
Well deserved VU2ESE..
73 Steve
G1KQH
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Hi Art!
There's no such thing as an Arduino Mini STMF103. For sure, you have an Arduino Nano board solderd into your Raduino board. The STM line of processors and boards are a completely different animal with much more capability and higher performance. The goal of this project is to convert the Raduino board to run with an STM processor. Kind of like transplanting a V8 engine into a VW Beetle.?
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Skip Davis
Jim Sheldon