Re: Chip YWN3M2NB

On Sat, Aug 14, 2021 at 06:47 AM, Peter McCracken wrote:

That's the audio amp, LM386T

the UTG2822M is NOT a LM386!
TDA2822M (second source) was problematic on the V3. (did not meet original manufactures SOA)

Mor, what version of the uBITX do you have?? (assume V3) What input voltage were you running?
Might want to drop the voltage to the TDA2822M down to ~9V.

I was one of the lucky ones who purchased a V3 with the problematic IC prior to it being socketed.
After pulling the IC (which really wasn't much of a chore) , I added a socket and replaced with an ST micro IC (15V Vmax).

Rgds,
Gary

Re: Chip YWN3M2NB

#89797

Just ordered the chips .I hope there are no other things going up in smoke?
73,
OM3MK
Mor

Re: Nouveau Retro Linear Amp Designs

#89796

Tom,

Since you would be just adjusting for a specific "condition" I wouldn't think positional feedback would be a "gotta have" in this situation.? As far as re-homing you would put a limit switch on each end of the revolution.? I have converted a couple of small manual machine tools to CNC and aside from some of the mechanical "challenges" it's pretty simple...

73,

Justin B.
KI5GKD

Re: Nouveau Retro Linear Amp Designs

#89795

Hi,

My understanding of those "round" plates with the axis in the "center" were designed that way to support mechanical dial linearity. Many times the plates are not truly circular and sometimes are obviously elliptical. The axis is also not exactly centered in many of them. There have been other form factors even as far back as the olde dayes to address other factors. Cost may have been one (doubtful), mechanical stability another, and space saving another. Now that we are using digital dials we are less bound to those "round" (not always so round) designs. Coaxial sliding cylinders (piston capacitors), plates that pivot at a 'corner', and others that fold along one edge like a book binding included have been around a long time. Antenna tuners (and plate resonance dippers) do not need a linear mechanical dial or even a digital electronic indicator of frequency. Plate current dipping or SWR are the indicators and do not have to use a linear display.

There is no reason to not build your own variable capacitors. Just keep "Q" and voltage ratings in mind. Mechanical stability may have more or less importance depending on application. Better be pretty tight for an L-C VFO :)

73,

Bill? KU8H

bark less - wag more

Show quoted text

On 8/13/21 7:56 PM, Arv Evans wrote:
Trying to get away from metal plates that rotate around a center point
leads one to thinking about pivoting the plates at a corner instead at
the middle.

Thin plastic from water bottles or soda bottles makes fairly good
dielectric separators.? Making up plates and a plastic separator
allows you to calculate the dielectric constant of the plastic if you
have a way to measure the capacitance.? Being able to measure
the thickness of several plastic plates will allow you to use multiple
separators, or to include both air separation and plastic spacers.

The idea of sliding variable capacitors, or trombone caps, have
been used for several years in the construction of loop antennas.
I live in Idaho, USA where we get snow, freezing rain, and ice.
This made the sliding capacitor a poor idea for my outside antenna
games. Instead I built rotating capacitors inside plastic food freezer
boxes. This works well as long as we don't get freezing condensate
inside the protective housings.? NOTE: painting the freezer containers
with dark paint helps keep the inside warmer and stops UV rays from
damaging the boxes.

The idea of sliding capacitors does work well for VFO designs and
other locations that are not exposed to the elements.

Fixed capacitance between two fixed plates can be made variable
by sliding a dielectric (plastic sheet) between the fixed plates.
Once you know the dielectric factor of plastic versus air you can
calculate the effect of replacing the air with dielectric factor of
the plastic.

Small DC motors from toys can be used to turn threaded rods or
3D printed gears to make up your own junk-box speed reducers.
Use micro-switches or homemade switches to limit degree of turn
for these systems.

Arv
_._


On Fri, Aug 13, 2021 at 5:34 PM barry halterman <kthreebo@... <mailto:kthreebo@...>> wrote:

    ?polyvaricon? capacitors, sheets of thin plastic between thin
    aluminum plates, were used in QRP tuners many moons ago. I built
    one up in the early 70's and never had an issue with the cap..
    Adding a servo would be a cool move and an interesting project.
    Barry
    K3bo

    On Fri, Aug 13, 2021, 4:16 PM Tom, wb6b <wb6b@...
    <mailto:wb6b@...>> wrote:

        On Fri, Aug 13, 2021 at 10:23 AM, Arv Evans wrote:

            While variable capacitors are becoming difficult to find,
            if you are
            mechanically inclined

        Hi Art,

        That DIY variable capacitor build video was really
        interesting. The modern world of 3D printers mashed up with
        the technology world of nearly 100 years ago.

        I was pondering, before those really inexpensive?atu-100
        antenna tuners came along, doing something similar for an
        antenna tuner, with microprocessor controlled RC servos tuning
        a good old fashioned PI matching network, and putting the
        little contraption as the base of my antenna.

        Seems like variable capacitors could be simplified if we get
        away from thinking they need to have components that rotate
        around shafts.

        Was thinking about just sliding, in a linear motion, a small
        stack of plates, like G10 PC boards or even aluminum plates
        separated by sheets cut from sandwich bags. If it is moved by
        a RC servo, the need for a human friendly rotating shaft and
        knob is not needed.

        Ashhar points out in his 25 watt linear amplifier design, if
        you are willing to stay below some wattage point the
        difference between the component requirements and cost can be
        huge.
        
        <>

        Tom, wb6b 

Re: Chip YWN3M2NB

#89794

Thanks for the quick answer Peter, wiring looks good, I also have to replace the 2Amp fuse luckily because otherwise.... I'll look on Ebay thanks Nice Week End

Have fun Mor

OPN3MK

73,

Re: Chip YWN3M2NB

#89793

That's the audio amp, LM386, I would check your wiring, where have you connected your speaker to ?

You can buy these cheaps off ebay / ali and elsewhere for little money.

Best regards, Peter.

Chip YWN3M2NB

#89792

There is a chip that starts smoking with the 8 legs. I can still see the number YWN3M2NB UTG2822M next to the blue capacitors. Where can I find these please ?
I didn't do anything wrong myself, when the uBITX came home in the mail I heard something rattle. It was the speaker, I'm sure it destroyed the chip
Thanks in advance
Mor
ON3MK??

Re: Nouveau Retro Linear Amp Designs

#89791

I remember seeing a capacitor made out of two tin cans, one inside the other. I can not remember all the details of how it was constructed but it was cheap.

K3bo

Show quoted text

On Sat, Aug 14, 2021, 3:02 AM Tom, wb6b <wb6b@...> wrote:

On Fri, Aug 13, 2021 at 07:42 PM, Ashhar Farhan wrote:

For fixed value, high voltage capacitors, you can just use RG58 coax. Use the shield and core as two ends of the capacitors. You can trim the length to trim the capaictance. Each band can have its set of pi matching circuit
True. And maybe using the inexpensive eBay relay boards, you could go all out and have several pre-tunned selections available in each band (such as 75m phone and 80m CW optimized selections), if one selection is too narrow. That would be a nice way to make a cost effective remote tuner.

Tom, wb6b

Re: The Mythbuster has several BITX circuits (video)

#89790

On Sun, Aug 1, 2021 at 08:37 AM, Jerry Gaffke wrote:

Actually, normal people would just go to rev01 of the PCB.

Wow, how that was done without at least a dozen hidden solder bridges is amazing. Worst yes the wiring looks like they accidentally mirrored the layout of the pins.?

Must have really slow PCB service. Must have taken forever to do the hand wiring, not to mention the timing changes introduced by the wires.?

Maybe some budget minded manger stepped in with a manager's gift of common sense and forced them to do that.?

Tom, wb6b

Re: Manuel or video

Herman Tempelman

#89789

uw versie nummer staat bij de aansluiting van de antenne connector

Op vr 13 aug. 2021 om 21:45 schreef maurits <mauritsvandriessche@...>:

Show quoted text

OK I will do that
Kind Regards?
Mor 73,
ON3MK?

Re: Nouveau Retro Linear Amp Designs

#89788

On Fri, Aug 13, 2021 at 07:42 PM, Ashhar Farhan wrote:

For fixed value, high voltage capacitors, you can just use RG58 coax. Use the shield and core as two ends of the capacitors. You can trim the length to trim the capaictance. Each band can have its set of pi matching circuit

True. And maybe using the inexpensive eBay relay boards, you could go all out and have several pre-tunned selections available in each band (such as 75m phone and 80m CW optimized selections), if one selection is too narrow. That would be a nice way to make a cost effective remote tuner.

Tom, wb6b

Re: Nouveau Retro Linear Amp Designs

#89787

On Fri, Aug 13, 2021 at 10:29 PM, Justin Bowser - KI5GKD wrote:

It would be super simple to use an Arduino and support circuitry to drive stepper motors.

These stepping motor/driver combos could be a good choice in-between the designs I've seen that use more expensive stepping motors that are typically used on 3D printers and CNC mills, and the cheap RC servos I'd been thinking about.

They would likely have finer control of the variable capacitor, but not as pricy as the bigger stepping motors. They have a reduction gear train in them and a little play in the shaft rotation. But, many application wouldn't need the exacting precision of the 3D printer type stepping motor.?

There seems to be a lot of this style stepping motor available for Arduino projects. Somewhere I read they are (or were) built to control air vents on some kind of consumer cooling system. ?

The RC servos have the advantage of having position feedback built in and being controlled for absolute (if you consider absolute to be pretty low tolerance) position. I believe the stepping motors above might be able to be re-homed by simply running them to a hard stop and supplying enough steps to know it would have run into the stop at some point.

Tom, wb6b

Re: Nouveau Retro Linear Amp Designs

#89786

On Fri, Aug 13, 2021 at 04:46 PM, Ashhar Farhan wrote:

The polyvaricon have horrible Q. The glass epoxy copper clads used as capacitors too have shown bad Q.

Would DIY polyvaricon or glass epoxy PC board variable capacitors work well for PI or L type antenna tuners? Is the Q requirement less critical there?

Whereas resonate RF tank circuits (if they are to work well for harmonic suppression) need high Q designs. Loop Antenna tuning needs to be high Q to be efficient. For low pass filters, is high Q critical or do you just make up for it with more poles?

Tom, wb6b

Re: Nouveau Retro Linear Amp Designs

#89785

Yes, Justin,

He made the front and back out of acrylic laser cutouts. Used nuts are spacers.

Show quoted text

On Sat, Aug 14, 2021, 10:59 AM Justin Bowser - KI5GKD <justin.bowser@...> wrote:

Tom - It would be super simple to use an Arduino and support circuitry to drive stepper motors.

Ashhar - So VU3BVB made the capacitor frames from acrylic?? That would be very doable with the CNC machines I have.

73,

Justin B.
KI5GKD?

Re: Nouveau Retro Linear Amp Designs

#89784

Tom - It would be super simple to use an Arduino and support circuitry to drive stepper motors.

Ashhar - So VU3BVB made the capacitor frames from acrylic?? That would be very doable with the CNC machines I have.

73,

Justin B.
KI5GKD?

Re: Nouveau Retro Linear Amp Designs

#89783

开云体育

Tom:

I remember reading a QST article about creating tubular variable capacitors. You will have to look in the QST 1980's archives for the article. As I recall, these tubular variable capacitors were then used in building a antenna tuner. Suggest locating this article to see ?if this would be a valid variable capacitor solution.

73 Dave WD8AJQ!?

5

Show quoted text

On Aug 13, 2021, at 4:16 PM, Tom, wb6b <wb6b@...> wrote:

On Fri, Aug 13, 2021 at 10:23 AM, Arv Evans wrote:

While variable capacitors are becoming difficult to find, if you are

mechanically inclined

Hi Art,

That DIY variable capacitor build video was really interesting. The modern world of 3D printers mashed up with the technology world of nearly 100 years ago.?

I was pondering, before those really inexpensive?atu-100 antenna tuners came along, doing something similar for an antenna tuner, with microprocessor controlled RC servos tuning a good old fashioned PI matching network, and putting the little contraption as the base of my antenna.

Seems like variable capacitors could be simplified if we get away from thinking they need to have components that rotate around shafts.

Was thinking about just sliding, in a linear motion, a small stack of plates, like G10 PC boards or even aluminum plates separated by sheets cut from sandwich bags. If it is moved by a RC servo, the need for a human friendly rotating shaft and knob is not needed.

Ashhar points out in his 25 watt linear amplifier design, if you are willing to stay below some wattage point the difference between the component requirements and cost can be huge.
?
Tom, wb6b

Re: Nouveau Retro Linear Amp Designs

Terry VK5TM

#89782

Here is one example of a nicely done homebrew motor controlled capacitor (this one is for a loop but could be used for other antenna's).

Click the 'Official Build Document Link' for a pdf with a nice pic of the finished thing on the last page.

I can't find it at the moment, but the previous suggestion of motor controlled sliding plates is also out there on the 'net somewhere, along with many others - mainly associated with loop antenna's.
--

Re: Nouveau Retro Linear Amp Designs

#89781

For fixed value, high voltage capacitors, you can just use RG58 coax. Use the shield and core as two ends of the capacitors. You can trim the length to trim the capaictance. Each band can have its set of pi matching circuit

Show quoted text

On Sat, Aug 14, 2021, 5:27 AM Arv Evans <arvid.evans@...> wrote:

Trying to get away from metal plates that rotate around a center point
leads one to thinking about pivoting the plates at a corner instead at
the middle.?

Thin plastic from water bottles or soda bottles makes fairly good
dielectric separators.? Making up plates and a plastic separator
allows you to calculate the dielectric constant of the plastic if you
have a way to measure the capacitance.? Being able to measure
the thickness of several plastic plates will allow you to use multiple
separators, or to include both air separation and plastic spacers.

The idea of sliding variable capacitors, or trombone caps, have
been used for several years in the construction of loop antennas.
I live in Idaho, USA where we get snow, freezing rain, and ice.?
This made the sliding capacitor a poor idea for my outside antenna
games.? Instead I built rotating capacitors inside plastic food freezer
boxes.? This works well as long as we don't get freezing condensate
inside the protective housings.? NOTE: painting the freezer containers
with dark paint helps keep the inside warmer and stops UV rays from
damaging the boxes.

The idea of sliding capacitors does work well for VFO designs and
other locations that are not exposed to the elements.

Fixed capacitance between two fixed plates can be made variable
by sliding a dielectric (plastic sheet) between the fixed plates.?
Once you know the dielectric factor of plastic versus air you can
calculate the effect of replacing the air with dielectric factor of
the plastic.

Small DC motors from toys can be used to turn threaded rods or
3D printed gears to make up your own junk-box speed reducers.
Use micro-switches or homemade switches to limit degree of turn
for these systems.

Arv
_._

On Fri, Aug 13, 2021 at 5:34 PM barry halterman <kthreebo@...> wrote:
?polyvaricon? capacitors, sheets of thin plastic between thin aluminum plates, were used in QRP tuners many moons ago. I built one up in the early 70's and never had an issue with the cap.. Adding a servo would be a cool move and an interesting project.
Barry
K3bo

On Fri, Aug 13, 2021, 4:16 PM Tom, wb6b <wb6b@...> wrote:
On Fri, Aug 13, 2021 at 10:23 AM, Arv Evans wrote:

While variable capacitors are becoming difficult to find, if you are

mechanically inclined

Hi Art,

That DIY variable capacitor build video was really interesting. The modern world of 3D printers mashed up with the technology world of nearly 100 years ago.?

I was pondering, before those really inexpensive?atu-100 antenna tuners came along, doing something similar for an antenna tuner, with microprocessor controlled RC servos tuning a good old fashioned PI matching network, and putting the little contraption as the base of my antenna.

Seems like variable capacitors could be simplified if we get away from thinking they need to have components that rotate around shafts.

Was thinking about just sliding, in a linear motion, a small stack of plates, like G10 PC boards or even aluminum plates separated by sheets cut from sandwich bags. If it is moved by a RC servo, the need for a human friendly rotating shaft and knob is not needed.

Ashhar points out in his 25 watt linear amplifier design, if you are willing to stay below some wattage point the difference between the component requirements and cost can be huge.
?
Tom, wb6b

Re: Nouveau Retro Linear Amp Designs

#89780

Trying to get away from metal plates that rotate around a center point

leads one to thinking about pivoting the plates at a corner instead at

the middle.?

Thin plastic from water bottles or soda bottles makes fairly good

dielectric separators.? Making up plates and a plastic separator

allows you to calculate the dielectric constant of the plastic if you

have a way to measure the capacitance.? Being able to measure

the thickness of several plastic plates will allow you to use multiple

separators, or to include both air separation and plastic spacers.

The idea of sliding variable capacitors, or trombone caps, have

been used for several years in the construction of loop antennas.

I live in Idaho, USA where we get snow, freezing rain, and ice.?

This made the sliding capacitor a poor idea for my outside antenna

games.? Instead I built rotating capacitors inside plastic food freezer

boxes.? This works well as long as we don't get freezing condensate

inside the protective housings.? NOTE: painting the freezer containers

with dark paint helps keep the inside warmer and stops UV rays from

damaging the boxes.

The idea of sliding capacitors does work well for VFO designs and

other locations that are not exposed to the elements.

Fixed capacitance between two fixed plates can be made variable

by sliding a dielectric (plastic sheet) between the fixed plates.?

Once you know the dielectric factor of plastic versus air you can

calculate the effect of replacing the air with dielectric factor of

the plastic.

Small DC motors from toys can be used to turn threaded rods or

3D printed gears to make up your own junk-box speed reducers.

Use micro-switches or homemade switches to limit degree of turn

for these systems.

Arv

_._

Show quoted text

On Fri, Aug 13, 2021 at 5:34 PM barry halterman <kthreebo@...> wrote:

?polyvaricon? capacitors, sheets of thin plastic between thin aluminum plates, were used in QRP tuners many moons ago. I built one up in the early 70's and never had an issue with the cap.. Adding a servo would be a cool move and an interesting project.
Barry
K3bo

On Fri, Aug 13, 2021, 4:16 PM Tom, wb6b <wb6b@...> wrote:
On Fri, Aug 13, 2021 at 10:23 AM, Arv Evans wrote:

While variable capacitors are becoming difficult to find, if you are

mechanically inclined

Hi Art,

That DIY variable capacitor build video was really interesting. The modern world of 3D printers mashed up with the technology world of nearly 100 years ago.?

I was pondering, before those really inexpensive?atu-100 antenna tuners came along, doing something similar for an antenna tuner, with microprocessor controlled RC servos tuning a good old fashioned PI matching network, and putting the little contraption as the base of my antenna.

Seems like variable capacitors could be simplified if we get away from thinking they need to have components that rotate around shafts.

Was thinking about just sliding, in a linear motion, a small stack of plates, like G10 PC boards or even aluminum plates separated by sheets cut from sandwich bags. If it is moved by a RC servo, the need for a human friendly rotating shaft and knob is not needed.

Ashhar points out in his 25 watt linear amplifier design, if you are willing to stay below some wattage point the difference between the component requirements and cost can be huge.
?
Tom, wb6b

Re: Nouveau Retro Linear Amp Designs

#89779

The polyvaricon have horrible Q. The glass epoxy copper clads used as capacitors too have shown bad Q. However, there are other venues opened up. My friend Venu, VU3BVB, got aluminium plates cut on a local laser cutting shop and assembled a variable capacitor with acrylic sheets as support and some off the shelf screws. All in all abiut 5 dollars worth parts. It looks monstrous.?

- f

Show quoted text

On Sat, Aug 14, 2021, 5:04 AM barry halterman <kthreebo@...> wrote:

?polyvaricon? capacitors, sheets of thin plastic between thin aluminum plates, were used in QRP tuners many moons ago. I built one up in the early 70's and never had an issue with the cap.. Adding a servo would be a cool move and an interesting project.
Barry
K3bo

On Fri, Aug 13, 2021, 4:16 PM Tom, wb6b <wb6b@...> wrote:
On Fri, Aug 13, 2021 at 10:23 AM, Arv Evans wrote:

While variable capacitors are becoming difficult to find, if you are

mechanically inclined

Hi Art,

That DIY variable capacitor build video was really interesting. The modern world of 3D printers mashed up with the technology world of nearly 100 years ago.?

I was pondering, before those really inexpensive?atu-100 antenna tuners came along, doing something similar for an antenna tuner, with microprocessor controlled RC servos tuning a good old fashioned PI matching network, and putting the little contraption as the base of my antenna.

Seems like variable capacitors could be simplified if we get away from thinking they need to have components that rotate around shafts.

Was thinking about just sliding, in a linear motion, a small stack of plates, like G10 PC boards or even aluminum plates separated by sheets cut from sandwich bags. If it is moved by a RC servo, the need for a human friendly rotating shaft and knob is not needed.

Ashhar points out in his 25 watt linear amplifier design, if you are willing to stay below some wattage point the difference between the component requirements and cost can be huge.
?
Tom, wb6b