That total gate charge has to be BOTH charged and discharged with your CW to maintain low phase and harmonic distortion. Thus your max. frequency? then gives you an idea of the amount of gate drive needed to achieve this.
--
AncelB, MIT EE6002
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Re: Home brew 5 band BitX
Hi to all.I have built the G6LBQ BITX with local spare parts & i wanted a 4 bands as i have 3bands hf & a 6m antennas.I changed the Q1 & Q11 Transistor with a lownoise ones and i added a 2N5109+2SC1971 for my 5w PA Modul. The BPF were changed with the PA3AKE design for hf and a 6m coupled bpf. the bpf were tuned with AirSpy & a noise generator.Perfect.The IF is the problem as i haven't good crystals to make a ladder filter i tried to do it with a commercial one but with some impedance mismatch.I worked with it in all bands specially my love 6m Band.
Hope will help & encourage..73s de CN8LI/Said.
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Re: uBitx almost finished by Bore Lezaic into CM2KMK PCB
P.S. this CM2KMK version is based on very old (1st) Farhan's schematic. See my blog for details:
On Thursday, November 16, 2017, 9:47:19 AM GMT+2, Dimitar Pavlov via Groups.Io <lz1dpn@...> wrote:
Hi,
I never see video with QSO from Bore (and other) with uBitx. He and I builded CM2KMK version (Bore with SBL-1, I'm build original Heriberto CM2KMK design). Receiver is worked, but transmitter is not worked. I think, signal level from last mixer is very low and not drive PA stage transistors. I'm freeze this project now (I'm build 2 versions - 1 original CM2KMK and 1 with LZ1LDO modification in PA stage). Also audio (with TDA2282) and AGC provide very poor and low audio signal in both versions (my friend LZ1CLK also build original CM2KMK version, and also have similar problems in audio stage). I don't know why. I think, we need to wait finished Mr. Farhan development and buy from him original uBitx ;)
73!
On Wednesday, November 15, 2017, 3:54:13 PM GMT+2, Lawrence Galea <9h1avlaw@...> wrote:
Is it possible to have a PDF file so one can make them at home? Tnx Lawrence
On Tue, Aug 8, 2017 at 11:04 AM, Richard Andrew Knack via Groups.Io <ihc73scout2@...> wrote: Folks, the fellow in Cuba who designed the single-sided board sent me the GERBER files, etc. I have posted then in the "files" section of this group in a file called "UBitx files from Cuba".
Rich KC8MWG
On Tuesday, August 8, 2017, 2:47:30 AM EDT, Ashhar Farhan < farhanbox@...> wrote:
thanks all. i am going to try and get this baby out soon now..
- f
|
Re: uBitx almost finished by Bore Lezaic into CM2KMK PCB
Hi,
I never see video with QSO from Bore (and other) with uBitx. He and I builded CM2KMK version (Bore with SBL-1, I'm build original Heriberto CM2KMK design). Receiver is worked, but transmitter is not worked. I think, signal level from last mixer is very low and not drive PA stage transistors. I'm freeze this project now (I'm build 2 versions - 1 original CM2KMK and 1 with LZ1LDO modification in PA stage). Also audio (with TDA2282) and AGC provide very poor and low audio signal in both versions (my friend LZ1CLK also build original CM2KMK version, and also have similar problems in audio stage). I don't know why. I think, we need to wait finished Mr. Farhan development and buy from him original uBitx ;)
73!
On Wednesday, November 15, 2017, 3:54:13 PM GMT+2, Lawrence Galea <9h1avlaw@...> wrote:
Is it possible to have a PDF file so one can make them at home? Tnx Lawrence
On Tue, Aug 8, 2017 at 11:04 AM, Richard Andrew Knack via Groups.Io <ihc73scout2@...> wrote: Folks, the fellow in Cuba who designed the single-sided board sent me the GERBER files, etc. I have posted then in the "files" section of this group in a file called "UBitx files from Cuba".
Rich KC8MWG
On Tuesday, August 8, 2017, 2:47:30 AM EDT, Ashhar Farhan < farhanbox@...> wrote:
thanks all. i am going to try and get this baby out soon now..
- f
|
Barrett,
Try reducing the value of R123 by putting a lower value in parallel. Start with 47 or 33 and go down to 10 Ohms.
The gain will increase for the mic.
Raj
toggle quoted message
Show quoted text
At 15/11/2017, you wrote: I went ahead and set it back to 100 ma. Is there a link that can show me how to make or buy a preamp for the mic?
--
Barrett
K5SSO
|
Re: CW ON BITX WITH CODE OSCILLATOR
Yes, this is the one I saw!
The oscillator in lower left side.
Raj
At 15/11/2017, you wrote:
toggle quoted message
Show quoted text
I don?€?t know what happened to
the link. Guess I bought the last one. Here was a screenshot
![[]](/g/BITX20/attachment/34609/)
73
Ben
KD2NOU?
On Wed, Nov 15, 2017 at 10:10 AM Jerry Gaffke via Groups.Io
<jgaffke=[email protected]
> wrote:
- Very very odd indeed.
- I just cleared my browser cache, can still follow that link and get
an image of the $14.95 LM555 oscillator.
- Perhaps that ebay store is playing games with our geographical
locations, and we see whatever they happen
- to have stocked in the warehouse that's cheapest to ship from?
- From this it seems we should not be trusting ebay links.
- When recommending some ebay item that worked for us, might be best to
include a brief description.
- And perhaps a photo.
- Jerry, KE7ER
- On Wed, Nov 15, 2017 at 03:12 am, Raj vu2zap wrote:
- Very odd Jerry,
- That item says out of stock and nothing displays. When I checked it
originally it had a 386 and a transistor and many
- passive components.
- I guess someone here has bought it and can tell us more.
|
Re: Antenna Analyzer problems.
Nice to hear you got things working Karl.
I am trying to make a document with some testing and troubleshooting info.
The first attempt is on?Edwin PE1PWF
|
The IRF510 has a typical drain voltage rating of 70v. That is why the DC voltage maximum
is typically 48v. This allows a signal excursion of about 96v with only an occasional peak
of 96v. There is some distortion but it is hardly noticeable.
The typical drain voltage of the IRF610 is about 100v. Hence one can use a little higher
DC and signal voltage. Probably about 20% or so. That means about 30-40% more power
output. Even at 48v, the power output would be a it cleaner.
john
AD5YE
|
800 pf of gate capacitance (like 5 times that of the irf510) -- which at 20 meters would have a capacitive reactance of 14 ohms....
Gordon,? how U count 14 Ohm at 800 Pf?? & how much inductance will be needed Sir...
if you tuned that with a parallel inductor of course this would change a lot......
The gate capacitance is different, so you would need to adjust the input coupling to them to start with.
There also may not be enough drive power, so an extra drive stage might be needed.
Terry VK5TM
-- { mailed mobile }
|
Thank you for explaining the miller effect.? I keep learning here!
This article discuses high power high efficiency MOSFET amplifier design at just about 20 meters:
?
Interestingly, the GATE INDUCTANCE is an issue for this designer and they literally designed a circuit to resonate with that.? ?The voltage that Ryan Flowers measured at the gate terminal.....isn't actually what drives the device....it is what makes it to
the gate capacitance after traversing the gate inductance....
So here we have yet another low pass filter problem that can lower the gain of a simple amplifier at higher frequencies.? ?The BITX40 does not have a tuned gate drive circuit, just a tranformer (?auto transformer?) from Q14....? ?So the actual drive voltage
to the die may well decline with frequency......
I went and looked at my bitx40 and the source is soldered right to the ground plane on the bottom of the board, and the top has a trace that goes out a ways and then thru a via to the bottom as well, both attempts to reduce the source lead inductance I believe.?
?So that part looked optimized to me.? ?
the combination of the device's inherent gate low pass filter and the source inherent inductance in the bond wires both tend to reduce the "apparent" gain at higher frequencies...
gordon
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Show quoted text
Gate to drain capacitance is the more significant.
As the gate voltage rises by perhaps 1 volt, the drain voltage might fall by 10v or more
due to the gain of the FET. ?This effectively multiplies the effect of the gate-to-drain
capacitance by a factor of 10. ?This effect is called the miller capacitance.
Switching FETs have a spec called Total Gate Charge, in nano-Coulombs.
That is perhaps the best spec to determine the amount of drive that will be required
On Wed, Nov 15, 2017 at 05:27 pm, Michael Hagen wrote:
Probably compare Gate to Source input Capacitance.? The lower the better.
|
How much power can we get from a 610
On 16 Nov. 2017 1:18 pm, "John Backo via Groups.Io" <iam74= [email protected]> wrote: A direct replacement for the IRF510 is the IF610. Except for drain voltage tolerance,
they are very similar.
Other types can be used, but pay close attention to the specs. If they are too far off,
especially gate capacitance, don't use them, or modify the circuit accordingly.
The IRF630 is not a good substitute for the IRF510. The IRF614 is an odd MOSFET, and may work.
Check the data sheet.
john
AD5YE
|
A direct replacement for the IRF510 is the IF610. Except for drain voltage tolerance,
they are very similar.
Other types can be used, but pay close attention to the specs. If they are too far off,
especially gate capacitance, don't use them, or modify the circuit accordingly.
The IRF630 is not a good substitute for the IRF510. The IRF614 is an odd MOSFET, and may work.
Check the data sheet.
john
AD5YE
|
Gate capacitance is a function of supply voltage, so it pays to take a close look at the
gate capacitance chart and note what it is for your operating voltage.
_._
On Wed, Nov 15, 2017 at 6:51 PM, Trent Trent <vk7hrs@...> wrote: What would have to be chsnged if i used a rh1hf or whstever it is?
|
Gate to drain capacitance is the more significant.
As the gate voltage rises by perhaps 1 volt, the drain voltage might fall by 10v or more
due to the gain of the FET. ?This effectively multiplies the effect of the gate-to-drain
capacitance by a factor of 10. ?This effect is called the miller capacitance.
Switching FETs have a spec called Total Gate Charge, in nano-Coulombs.
That is perhaps the best spec to determine the amount of drive that will be required
toggle quoted message
Show quoted text
On Wed, Nov 15, 2017 at 05:27 pm, Michael Hagen wrote:
Probably compare Gate to Source input Capacitance.? The lower the better.
|
What would have to be chsnged if i used a rh1hf or whstever it is?
On 16 Nov. 2017 12:36 pm, "Gordon Gibby" < ggibby@...> wrote:
?one of the two proposed has 800 pf of gate capacitance (like 5 times that of the irf510) -- which at 20 meters would have a capacitive reactance of 14 ohms.....so a feed with an impedance of 100 ohms won't do so well.....? ?
if you tuned that with a parallel inductor of course this would change a lot......
but that is more complicated.
The gate capacitance is different, so you would need to adjust the input coupling to them to start with.
There also may not be enough drive power, so an extra drive stage might be needed.
Terry VK5TM
|
?one of the two proposed has 800 pf of gate capacitance (like 5 times that of the irf510) -- which at 20 meters would have a capacitive reactance of 14 ohms.....so a feed with an impedance of 100 ohms won't do so well.....? ?
if you tuned that with a parallel inductor of course this would change a lot......
but that is more complicated.
toggle quoted message
Show quoted text
The gate capacitance is different, so you would need to adjust the input coupling to them to start with.
There also may not be enough drive power, so an extra drive stage might be needed.
Terry VK5TM
|
The gate capacitance is different, so you would need to adjust the input coupling to them to start with.
There also may not be enough drive power, so an extra drive stage might be needed.
Terry VK5TM
|
Probably compare Gate
to Source input Capacitance.? The lower the better.
Mike, WA6ISP
On 11/15/2017 4:08 PM, Mark wrote:
I have some IRF630 Fets and am wondering if they would be
suitable for replacement for the 510?
I think they are a higher Voltage and Current device TO220
package.
So If I was to use said device? would the specs be close enough
or are they not sutable.
Cheers Mark
--
Mike Hagen, WA6ISP
10917 Bryant Street
Yucaipa, Ca. 92399
(909) 918-0058
PayPal ID "MotDog@..."
Mike@...
|
I ran across an IRF-614 in an old TV the other day, was wondering the same thing :) -- Ryan Flowers W7RLF
?
?<-- Learn how to go digital on the BITX40
|
I have some IRF630 Fets and am wondering if they would be suitable for replacement for the 510?
I think they are a higher Voltage and Current device TO220 package.
So If I was to use said device? would the specs be close enough or are they not sutable.
Cheers Mark
|
Ancel
Raj vu2zap
Mark G?NMY