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ubitx - stop press

 

I'd appreciate a functional description of the blocks as I'd like to introduce custom upgrades if I may.
I have the instrumentation to help with the project, Rigol DSA & TG, 8753D VNA, Tektronix Calibration gear for amplitude, 3 channel variable linear PSU, Agilent NF analyzer and noise source, Agilent F. counter, Rubidium reference, DSOs (4) , Sig gens - HP4432B? Digital, 6 1/2 digit DMMs, LCR meters, micro wattmeter (Boonton 4510), precision RF 50Ω loads, precision attenuators. Bird 43 with H band slug, 50W. ? All instrumentation gear good to 3Ghz or better.
--
AncelB, MIT EE6002
 

Thanks for the updated schematic!? What did you find that led to the change in the 45 MHz band pass filter (should the original LC network not be used?)?? Also - is it safe to assume that the pair 2N2219As were changed to 4 2N3904s in the driver to simplify or standardize the parts list?


On Fri, Oct 6, 2017 at 01:10 pm, Ashhar Farhan wrote:
I am plodding through the write-up part of the new version. in the meantime, here is just the schematic. not very different.
?
?
?
- f
?
 

This post says why Farhan went to the 45mhz crystal filter on the ubitx:
?/g/BITX20/message/33203


On Mon, Nov 20, 2017 at 01:44 pm, AndyH wrote:
Thanks for the updated schematic!? What did you find that led to the change in the 45 MHz band pass filter (should the original LC network not be used?)?? Also - is it safe to assume that the pair 2N2219As were changed to 4 2N3904s in the driver to simplify or standardize the parts list?
 

Thanks Jerry - I missed that.


On Mon, Nov 20, 2017 at 02:25 pm, Jerry Gaffke wrote:
This post says why Farhan went to the 45mhz crystal filter on the ubitx:
?/g/BITX20/message/33203

On Mon, Nov 20, 2017 at 01:44 pm, AndyH wrote:
Thanks for the updated schematic!? What did you find that led to the change in the 45 MHz band pass filter (should the original LC network not be used?)?? Also - is it safe to assume that the pair 2N2219As were changed to 4 2N3904s in the driver to simplify or standardize the parts list?
 

Just the close the circle, so to speak.? Farhan has additional comments in the sales write-up for the ?BITX:
The power chain uses four common plastic 2N3904s in push-pull as drivers. The 2N3904s have enough gain at 30 MHz. The 2N2219s tried ?earlier were found to have low gain at higher frequencies.
Andy, KG5RKP

On Mon, Nov 20, 2017 at 01:44 pm, AndyH wrote:
Thanks for the updated schematic!? What did you find that led to the change in the 45 MHz band pass filter (should the original LC network not be used?)?? Also - is it safe to assume that the pair 2N2219As were changed to 4 2N3904s in the driver to simplify or standardize the parts list?

On Fri, Oct 6, 2017 at 01:10 pm, Ashhar Farhan wrote:
I am plodding through the write-up part of the new version. in the meantime, here is just the schematic. not very different.
?
?
?
- f
?
 

The 2N2219 didn't have enough juice at higher HF frequencies (at least the ones in my junk box). The 2N3904s don't need a heatsink either.?

- f

On Mon, Dec 11, 2017 at 11:48 AM, AndyH <ahecker@...> wrote:
Just the close the circle, so to speak.? Farhan has additional comments in the sales write-up for the ?BITX:
The power chain uses four common plastic 2N3904s in push-pull as drivers. The 2N3904s have enough gain at 30 MHz. The 2N2219s tried ?earlier were found to have low gain at higher frequencies.
Andy, KG5RKP

On Mon, Nov 20, 2017 at 01:44 pm, AndyH wrote:
Thanks for the updated schematic!? What did you find that led to the change in the 45 MHz band pass filter (should the original LC network not be used?)?? Also - is it safe to assume that the pair 2N2219As were changed to 4 2N3904s in the driver to simplify or standardize the parts list?

On Fri, Oct 6, 2017 at 01:10 pm, Ashhar Farhan wrote:
I am plodding through the write-up part of the new version. in the meantime, here is just the schematic. not very different.
?
?
?
- f
?
 

Hfsignals.com write-up also mentions that power out is 10 Watts up to 10mhz, falls off to 2 Watts at 30mhz.
It is tough to drive IRF510's at 30mhz, but the WA2EBY amplifier uses two IRF510's in push-pull
like this to give 40 Watts up through 30mhz from a 28v supply. ?Perhaps we can borrow some of the
WA2EBY design to approach that kind of performance. ?May require beefier caps and coils.
And maybe?an additional driver stage.?
? ??
? ??http://www.golddredgervideo.com/kc0wox/wa2ebyamp/amppart2.pdf

Also in the hfsignals uBitx write-up: ?"TIA".
Not found in most dictionaries.
Means "Termination Insensitive Amplifier"
? ??

Jerry, KE7ER


On Sun, Dec 10, 2017 at 10:18 pm, AndyH wrote:
Just the close the circle, so to speak.? Farhan has additional comments in the sales write-up for the ?BITX:
The power chain uses four common plastic 2N3904s in push-pull as drivers. The 2N3904s have enough gain at 30 MHz. The 2N2219s tried ?earlier were found to have low gain at higher frequencies.
 

One could push it that high, but not on the same PCB as the rest of the circuitry. I would say that 30 watts should be the tops. the RF ground loops on the board can make the entire TX chain wobbly. that said, i haven't tried anything of the sort. I'm curious to know what happens, i havent transmitted more than 25 watts for two decades.

- f

On Mon, Dec 11, 2017 at 12:16 PM, Jerry Gaffke via Groups.Io <jgaffke@...> wrote:
Hfsignals.com write-up also mentions that power out is 10 Watts up to 10mhz, falls off to 2 Watts at 30mhz.
It is tough to drive IRF510's at 30mhz, but the WA2EBY amplifier uses two IRF510's in push-pull
like this to give 40 Watts up through 30mhz from a 28v supply.? Perhaps we can borrow some of the
WA2EBY design to approach that kind of performance.? May require beefier caps and coils.
And maybe?an additional driver stage.?
? ??
? ??

Also in the hfsignals uBitx write-up: ?"TIA".
Not found in most dictionaries.
Means "Termination Insensitive Amplifier"
? ??

Jerry, KE7ER


On Sun, Dec 10, 2017 at 10:18 pm, AndyH wrote:
Just the close the circle, so to speak.? Farhan has additional comments in the sales write-up for the ?BITX:
The power chain uses four common plastic 2N3904s in push-pull as drivers. The 2N3904s have enough gain at 30 MHz. The 2N2219s tried ?earlier were found to have low gain at higher frequencies.


REJIMON G
 

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I think C1969 ?in pushull mode will give constant power in all bands

Sent from my iPhone

On 11-Dec-2017, at 12:16 PM, Jerry Gaffke via Groups.Io <jgaffke@...> wrote:

write-up also mentions that power out is 10 Watts up to 10mhz, falls off to 2 Watts at 30mhz.
It is tough to drive IRF510's at 30mhz, but the WA2EBY amplifier uses two IRF510's in push-pull
like this to give 40 Watts up through 30mhz from a 28v supply. ?Perhaps we can borrow some of the
WA2EBY design to approach that kind of performance. ?May require beefier caps and coils.
And maybe?an additional driver stage.?
? ??
? ??

Also in the hfsignals uBitx write-up: ?"TIA".
Not found in most dictionaries.
Means "Termination Insensitive Amplifier"
? ??

Jerry, KE7ER


On Sun, Dec 10, 2017 at 10:18 pm, AndyH wrote:
Just the close the circle, so to speak.? Farhan has additional comments in the sales write-up for the ?BITX:
The power chain uses four common plastic 2N3904s in push-pull as drivers. The 2N3904s have enough gain at 30 MHz. The 2N2219s tried ?earlier were found to have low gain at higher frequencies.
 

I'm wondering if we can bring 30mhz output power up to the same level as 7mhz
by borrowing the WA2EBY matching network at the front of the IRF510's.
Two watts of SSB is pretty hardcore.


On Sun, Dec 10, 2017 at 10:53 pm, Ashhar Farhan wrote:
One could push it that high, but not on the same PCB as the rest of the circuitry. I would say that 30 watts should be the tops. the RF ground loops on the board can make the entire TX chain wobbly. that said, i haven't tried anything of the sort. I'm curious to know what happens, i havent transmitted more than 25 watts for two decades.
?
 

Try the?RD15HVF1. That is the simplest. The only the pin out is different, you will have to twist the the legs and figure how to insert them into the same pinout as the IRF510.

- f

On Mon, Dec 11, 2017 at 12:23 PM, REJIMON G <rejimontkm@...> wrote:
I think C1969 ?in pushull mode will give constant power in all bands

Sent from my iPhone

On 11-Dec-2017, at 12:16 PM, Jerry Gaffke via Groups.Io <jgaffke@...> wrote:

write-up also mentions that power out is 10 Watts up to 10mhz, falls off to 2 Watts at 30mhz.
It is tough to drive IRF510's at 30mhz, but the WA2EBY amplifier uses two IRF510's in push-pull
like this to give 40 Watts up through 30mhz from a 28v supply.? Perhaps we can borrow some of the
WA2EBY design to approach that kind of performance.? May require beefier caps and coils.
And maybe?an additional driver stage.?
? ??
? ??

Also in the hfsignals uBitx write-up: ?"TIA".
Not found in most dictionaries.
Means "Termination Insensitive Amplifier"
? ??

Jerry, KE7ER


On Sun, Dec 10, 2017 at 10:18 pm, AndyH wrote:
Just the close the circle, so to speak.? Farhan has additional comments in the sales write-up for the ?BITX:
The power chain uses four common plastic 2N3904s in push-pull as drivers. The 2N3904s have enough gain at 30 MHz. The 2N2219s tried ?earlier were found to have low gain at higher frequencies.
 

Jerry, you can crank up the 'volume' through the 100 ohms predriver preset.

- f

On Mon, Dec 11, 2017 at 12:27 PM, Jerry Gaffke via Groups.Io <jgaffke@...> wrote:
I'm wondering if we can bring 30mhz output power up to the same level as 7mhz
by borrowing the WA2EBY matching network at the front of the IRF510's.
Two watts of SSB is pretty hardcore.

On Sun, Dec 10, 2017 at 10:53 pm, Ashhar Farhan wrote:
One could push it that high, but not on the same PCB as the rest of the circuitry. I would say that 30 watts should be the tops. the RF ground loops on the board can make the entire TX chain wobbly. that said, i haven't tried anything of the sort. I'm curious to know what happens, i havent transmitted more than 25 watts for two decades.
?


 

OK, that's good to know.
Sounds like the uBitx can do better than 2W on 30mhz if you crank up the gain,
but best remember to crank it back down or you will distort when back on 7mhz.
And if that's too inconvenient, splurge on a couple RD15HVF1's ?(keeping it down at 12v).
Jerry, KE7ER


On Sun, Dec 10, 2017 at 11:05 pm, Ashhar Farhan wrote:
Jerry, you can crank up the 'volume' through the 100 ohms predriver preset.
?
- f
?
. . .

?

On Mon, Dec 11, 2017 at 12:27 PM, Jerry Gaffke via Groups.Io <jgaffke@...> wrote:
I'm wondering if we can bring 30mhz output power up to the same level as 7mhz
by borrowing the WA2EBY matching network at the front of the IRF510's.
Two watts of SSB is pretty hardcore.?
Trent Trent
 

With the rh15hvf or whatever they are does anything need to be changed like transformers and csn the PS power on it run 20V like the BitX40

On 11 Dec. 2017 6:05 pm, "Ashhar Farhan" <farhanbox@...> wrote:
Try the?RD15HVF1. That is the simplest. The only the pin out is different, you will have to twist the the legs and figure how to insert them into the same pinout as the IRF510.

- f

On Mon, Dec 11, 2017 at 12:23 PM, REJIMON G <rejimontkm@...> wrote:
I think C1969 ?in pushull mode will give constant power in all bands

Sent from my iPhone

On 11-Dec-2017, at 12:16 PM, Jerry Gaffke via Groups.Io <jgaffke@...> wrote:

write-up also mentions that power out is 10 Watts up to 10mhz, falls off to 2 Watts at 30mhz.
It is tough to drive IRF510's at 30mhz, but the WA2EBY amplifier uses two IRF510's in push-pull
like this to give 40 Watts up through 30mhz from a 28v supply.? Perhaps we can borrow some of the
WA2EBY design to approach that kind of performance.? May require beefier caps and coils.
And maybe?an additional driver stage.?
? ??
? ??

Also in the hfsignals uBitx write-up: ?"TIA".
Not found in most dictionaries.
Means "Termination Insensitive Amplifier"
? ??

Jerry, KE7ER


On Sun, Dec 10, 2017 at 10:18 pm, AndyH wrote:
Just the close the circle, so to speak.? Farhan has additional comments in the sales write-up for the ?BITX:
The power chain uses four common plastic 2N3904s in push-pull as drivers. The 2N3904s have enough gain at 30 MHz. The 2N2219s tried ?earlier were found to have low gain at higher frequencies.
REJIMON G
 

开云体育

hi, what's the maximum practical voltage,Vdd that can apply to IRF510.. I tested up to 37V for continuous one?
minute ....
Sent from my iPhone

On 11-Dec-2017, at 12:35 PM, Ashhar Farhan <farhanbox@...> wrote:

Jerry, you can crank up the 'volume' through the 100 ohms predriver preset.

- f

On Mon, Dec 11, 2017 at 12:27 PM, Jerry Gaffke via Groups.Io <jgaffke@...> wrote:
I'm wondering if we can bring 30mhz output power up to the same level as 7mhz
by borrowing the WA2EBY matching network at the front of the IRF510's.
Two watts of SSB is pretty hardcore.

On Sun, Dec 10, 2017 at 10:53 pm, Ashhar Farhan wrote:
One could push it that high, but not on the same PCB as the rest of the circuitry. I would say that 30 watts should be the tops. the RF ground loops on the board can make the entire TX chain wobbly. that said, i haven't tried anything of the sort. I'm curious to know what happens, i havent transmitted more than 25 watts for two decades.
?


 

Hi Ashhar,
I just noticed this issue now but ordered a ubitx on Friday.? I just wanted to confirm that the four filter option will be implemented on the radios that get shipped out.? Or will there be a different solution?

Thank you for coming up with these designs and taking the time and effort required to share them all over the world!

-Jeff
KF7RPI
 

He's indicated in other threads that the four filter version is final. It's also clear in the pictures of the production uBITX and the schematic. There's nothing to worry over :)

--
Ryan Flowers - W7RLF
 

The datasheet shows a max of 100V.?? But I haven't looked at the schematic to see if there are other components involved.?? So that's just for the device itself.? Of course keep it well below that.?

73, Michael
KM4OLT
 

Jerry,
?The IRF510 is really a general purpose device.? I think initially it was chosen in a lot of projects when it came out due to it's low on-resistance.? However it's not really a "rf device".?
This guy made a decent 50watt amp for the IRF510.?


? However this one uses true RF devices.? Which I think is a much better approach.? I haven't looked at the devices themselves closely to see if they could be substituted with the IRF510 or not directly.?? I was simply looking for a rf device that could be used for a new design. I just happened to see this discussion and share what information I have so far.?


?So maybe someone can expand the research.

73, Michael
KM4OLT
 

Thanks for your response Ryan!? I wasn't really worried about it; just didn't understand 100% from his post.? It is hackable and I could deal with it here.? I'm really excited about this radio!

-Jeff
KF7RPI

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