Re: technical question about filter capacitors
To measure really small caps, I've used a resonant circuit. You make up a coil of appropriate value and put it in series or parallel with the cap in question. Then
hook a scope and an oscillator. If you use a parallel resonant circuit, you need to put a series resistor so the
resonant tank has something to short out.
Once upon a time, I made a little jig to help me with such
endeavors. Of course, it only works with parts that have leads.
- Jerry KF6VB
toggle quoted message
Show quoted text
On 2021-05-04 12:28, Jerry Gaffke via groups.io wrote: I watched that 18 minute video so you don't have to.
Here's my review: He has a lab full of really nice gear.
His technique is to drive a 1v square wave from a 50 ohm source into
the cap,
measure the rise time t to 63.2%, or 632mV with a scope.
And calculate the capacitance from C = t/50ohms (C in Farads, t in
seconds).
Google for "RC time constant" if this is puzzling.
The caps he measured were all in the neighborhood of 1uF.
For some reason, he assumes one end of any cap is connected to the
ground plane.
He assumes there is nothing in parallel (except maybe an obvious row
of similar parts) with that cap.
Looking over the uBitx schematic, I see very few caps where this
technique would work.
My method for measuring caps (or resistors) in circuit:
Take it out of the circuit and measure it.
With reasonably long traces, some really fast test gear, and careful
technique,
you might be able to measure some low value individual components by
looking at
the reflection from that square wave before reflections from other
parts start coming in.
Good luck with that!
Jerry, KE7ER
On Mon, May 3, 2021 at 01:45 AM, Gerard wrote:
I put a video on it to find the value without desolding, but you
have to be equipped
And not sure his method work on very low capacitors.
(18) How to test or measure SMD capacitors on the PCB / on circuit
measurement free electronics training - YouTube [1] Links:
------
[1]
[2] /g/BITX20/message/88121
[3] /mt/82546658/243852
[4] /g/BITX20/post
[5] /g/BITX20/editsub/243852
[6] /g/BITX20/leave/10189903/243852/952924773/xyzzy
|
Re: technical question about filter capacitors
I watched that 18 minute video so you don't have to.
Here's my review:? ?? He has a lab full of really nice gear.
His technique is to drive a 1v square wave from a 50 ohm source into the cap,
measure the rise time t to 63.2%, or 632mV with a scope.
And calculate the capacitance from C = t/50ohms? (C in Farads, t in seconds).
Google for "RC time constant" if this is puzzling.
The caps he measured were all in the neighborhood of 1uF.
For some reason, he assumes one end of any cap is connected to the ground plane.
He assumes there is nothing in parallel (except maybe an obvious row of similar parts) with that cap.
Looking over the uBitx schematic, I see very few caps where this technique would work.
My method for measuring caps (or resistors) in circuit:
? Take it out of the circuit and measure it.
With reasonably long traces, some really fast test gear, and careful technique,
you might be able to measure some low value individual components by looking at
the reflection from that square wave before reflections from other parts start coming in.
Good luck with that!
Jerry, KE7ER
On Mon, May 3, 2021 at 01:45 AM, Gerard wrote:
I put a video on it to find the value without desolding, but you have to be equipped
And not sure his method work on very low capacitors.
|
Re: technical question about filter capacitors
The SMD parts I get from Digi-Key and Mouser come in small plastic labeled bags. I just leave them in the bags and line up the bags in storage boxes. The labels have the value, working voltage and part number.
?
I save the bags and reuse them for parts from other vendors. I write the new value on the label.
?
The bags are lined up by value.
?
Mike N2MS
?
On 05/04/2021 10:03 AM Jack, W8TEE via groups.io <jjpurdum@...> wrote:
?
?
?
Good idea. I typically take one jar and mount all of the caps/resistors of that value on the board at one time, then move on to the next value. As a result, I never have more than one jar open at a time. Also, they hang on the wall on a board and I wouldn't be able to read their values if the jar is labeled. However, if you store them on a shelf, or have a way to store them "laying on their side", your approach is more bullet proof.
?
Jack, W8TEE
?
On Tuesday, May 4, 2021, 7:52:16 AM EDT, Bill Cromwell <wrcromwell@...> wrote:
?
?
Hello Jack,
The only trouble with those labels is putting them on the
interchangeable lid. If it is possible for them to be swapped it *will*
happen. You are welcome to ask me how I know this. I recommend placing
the label on the jar.
73,
Bill KU8H
bark less - wag more
?
|
Re: technical question about filter capacitors
Gerard:
I would like to put a module that decodes the MORSE directly on a PC
This is very hard to do well. It's not too hard to get one to decode the W1AW code practice sessions because those are perfectly-generated characters. However, throw in a person's "fist" and things get considerably tougher. No individual can consistently maintain the 1-3-7 spacing that is required for good code parsing. There are a number of good ones out there like Hans' QCX and code by Bud Churchward, but still will hiccup along the way.
Jack, W8TEE
On Tuesday, May 4, 2021, 2:14:34 PM EDT, Gerard <kabupos@...> wrote:
Thank you Jerry for your response.
The basic question was what type of capacitors were on the filters at the output of the UBITX power amplifier.
The answer is clear, and given by the creator, it is SMD 100v.
I asked this question because on antenna tuner mounts we had 1000V capacitors.
Secondly, with regard to measurement, it is clear that testers have difficulty reading a value below 25PF.
In terms of the marking, clearly there is no marking.
I have SBM bands and the value is shown behind it.
You have to be careful, and I¡¯ve already been fooled on reading.
100 is not 100PF, but 10PF and 101 is 100PF.
Then concerning the storage, each to its own method.
I asked those questions, because in fact?I¡¯m back to electronics and my passion has always been radio.
I will still make changes on my Cocorico Ubitx and keep you informed, but of course, there are other things to do in the meantime.
Like here, I have provided modular SSB filters
Afterwards, and just out of curiosity, I would like to put a module that decodes the MORSE directly on a PC and made the reverse. But one thing at a time.
Cdt
-- Jack, W8TEE
|
Re: technical question about filter capacitors
Thank you Jerry for your response.
The basic question was what type of capacitors were on the filters at the output of the UBITX power amplifier.
The answer is clear, and given by the creator, it is SMD 100v.
I asked this question because on antenna tuner mounts we had 1000V capacitors.
Secondly, with regard to measurement, it is clear that testers have difficulty reading a value below 25PF.
In terms of the marking, clearly there is no marking.
I have SBM bands and the value is shown behind it.
You have to be careful, and I¡¯ve already been fooled on reading.
100 is not 100PF, but 10PF and 101 is 100PF.
Then concerning the storage, each to its own method.
I asked those questions, because in fact?I¡¯m back to electronics and my passion has always been radio.
I will still make changes on my Cocorico Ubitx and keep you informed, but of course, there are other things to do in the meantime.
Like here, I have provided modular SSB filters
Afterwards, and just out of curiosity, I would like to put a module that decodes the MORSE directly on a PC and made the reverse. But one thing at a time.
Cdt
|
Re: technical question about filter capacitors
If we are talking about storage, one that I use is coin envelopes and VCR tape boxes, that I have glued dividers in the width of the coin envelopes.? I expect VCR tape boxes are pretty rare? now days, shoe boxes might be a good? alternate.? I keep resistors, IC's, and any small parts that I want to keep on hand.? Hope I am not to far off topic. john kg9dk?
|
Re: technical question about filter capacitors
Hi,
I just string my SMD parts, by type and value, on a wire like on a fish stringer (threading through the last hole in the strip) and hang them on my workbench peg board.?? Takes up hardly any room and is very fast to find and take out parts from the strip.
73,? Mark
|
Re: technical question about filter capacitors
If you have a spare Nano clone for your Bitx40 or uBitx,? then you have all you need to build a capacitance meter: /g/BITX20/message/52471You can use the Arduino IDE serial monitor on your computer to read values from the Nano, or could be extravagant and blow an extra $2 on a 16x2 LCD. A couple probes on short wires works fine, you don't really need the tweezer thingies. On parts of only a few pF, hold the probes above the part first to get a zero reading, then subtract that value when probing the part. Resistors of size 0603 and larger seem to always be marked and quite readable under magnification.? For resistors of size?0402 and smaller they don't bother, though looks to me like there's plenty of room on an 0402. Surface mount ceramic caps are seldom marked, even when they are quite large. Perhaps the different finish on them would mean an extra processing step to print a value on it, and an additional $0.001 per part. Perhaps it's just because nobody else ever has, so customers don't expect it. Cap markings would be most welcome, just in case somebody from?Kemet/Murata/KOA/AVX/CTS/...? happens to be listening in. When building I do one part type at at time, dumping out and carefully counting enough? of that part to populate the board.? ?If that leaves an empty spot on the board, I know I put one in the wrong place.? I measure at least one of them, even if they are marked. The manufacturer very seldom goofs up on the value, but I goof up on reading it often enough. Jerry, KE7ER
|
Re: Split power for PA on uBITX v6
Hi,
Since there is still the 3pin header there, like in the previous versions, that seems the obvious place to input the higher voltage.? I imagine he just placed a joining trace between the previously unjoined power pins (unjoined so that users could easily input higher power separately to the finals).? You just have to check.? If so, you would just add another power jack to the rear panel going to pin#3 on the header.
73.
|
Re: technical question about filter capacitors
On 2021-05-04 10:05, jim via groups.io wrote: bought one of these.... Are you happy with it? A couple of Amazon reviews said it wasn't much good for caps. - Jerry KF6VB jim
On Monday, May 3, 2021, 1:45:21 PM PDT, Arv Evans
<arvid.evans@...> wrote:
Gerard
I'm probably wrong but maybe there are no markings on 805 and smaller
SMD capacitors because only a very few of us would be able to read the
writing. Possibly something new and radical like a series of colored
dots
would work, but still problematic for us ancient people.
I have a small isolated-tip tweezer with flexible test probe type
leads and
banana plug connection to a capacitor meter. Once I got used to the
equipment this lets me spread a handful of SMD components on a plastic
serving tray and quickly measure anything that looks like a capacitor.
Also works for resistors, and other measurable components.
These are then dropped in a fold of paper in order of value.
With a little practice this becomes second-nature and supports quick
sorting and easy circuit board assembly. Measure the value with the
tweezer tips open, then measure again with the component held in the
tweezer. Difference is actual component value with stray capacitance
factored out.
Arv
_._
On Mon, May 3, 2021 at 1:47 PM Gerard <kabupos@...> wrote:
One thing that is always annoying is that the value of a SMD
capacitor is almost never indicated.
I don¡¯t understand why manufacturers don¡¯t put a mark on the
capacitors , when they do it on resistors. That¡¯s probably a cost.
I put a video on it to find the value without desolding, but you
have to be equipped
And not sure his method work on very low capacitors.
(18) How to test or measure SMD capacitors on the PCB / on circuit
measurement free electronics training - YouTube [1]
cdt Links:
------
[1]
[2] /g/BITX20/message/88112
[3] /mt/82546658/243852
[4] /g/BITX20/post
[5] /g/BITX20/editsub/243852
[6] /g/BITX20/leave/10189903/243852/952924773/xyzzy
|
Re: technical question about filter capacitors
bought one of these....
jim
On Monday, May 3, 2021, 1:45:21 PM PDT, Arv Evans <arvid.evans@...> wrote:
Gerard
I'm probably wrong but maybe there are no markings on 805 and smaller
SMD capacitors because only a very few of us would be able to read the
writing.? Possibly something new and radical like a series of colored dots would work, but still problematic for us ancient people.
I have a small isolated-tip tweezer with flexible test probe type leads and
banana plug connection to a capacitor meter.? Once I got used to the
equipment this lets me spread a handful of SMD components on a plastic
serving tray and quickly measure anything that looks like a capacitor.?
Also works for resistors, and other measurable components.
These are then dropped in a fold of paper in order of value.?
With a little practice this becomes second-nature and supports quick
sorting and easy circuit board assembly.? Measure the value with the
tweezer tips open, then measure again with the component held in the
tweezer.? Difference is actual component value with stray capacitance
factored out.
Arv _._
On Mon, May 3, 2021 at 1:47 PM Gerard < kabupos@...> wrote: One thing that is always annoying is that the value of a SMD capacitor is almost never indicated.
I don¡¯t understand why manufacturers don¡¯t put a mark on the capacitors , when they do it on resistors. That¡¯s probably a cost.
I put a video on it to find the value without desolding, but you have to be equipped
And not sure his method work on very low capacitors.
cdt
|
Re: uBITX V6 Specifications.
|
Re: technical question about filter capacitors
The small jars remind me of a bacteria farm. LOL.
Each one has its own method, my SMD being in strips, I keep them in plastic bags.
It¡¯s not bad and spring prices here:
cdt
|
Re: uBITX V6 Specifications.
My 12v 20Ah LiFePo4 battery weighs about 7 lbs. What have you found that would weigh half of that?
Max KG4PID
On Tuesday, May 4, 2021, 09:52:05 AM CDT, Earl Cox via groups.io <kb5uew@...> wrote:
SSB, CW will be most of the time. I have not dived into digital yet. I am looking at 12V, 24AH. I can achieve that in a case of about 5 1/4" X 4" X 3 1/4" weighing a little over 3 lbs.
Earl Cox? KB5UEW? Reply or E-mail me at:? kb5uew@...
On Tuesday, May 4, 2021, 08:39:25 AM MDT, Evan Hand <elhandjr@...> wrote:
Earl,
I will verify when I get to my rig.? Until then, what mode will you be using?? SSB voice, vs CW, vs digital modes makes a difference.? If digital then I would estimate that you need 720mah and CW at slightly less than that.? SSB would have even lower requirements, most likely 50% of digital mode.? That means for 48 hours of continuous operation you would need a 34.5ah battery for digital and 18ah for SSB.? That would be a large battery.? Maybe look into a solar panel as a part of the power scheme.
Please check my math before you commit to a battery.
73
Evan
AC9TU
|
Hello All,
I am building a small linear amplifier to go with my uBITXv6. I got a tiny 70W RF deck from China - marketed as "100W", but that's only if you feed it 16V. Also a card with switchable bandpass filters. I'd like to build it into a case that
matches the V6. If I get ambitious, maybe even a matching touchscreen. Looked at the HFsignals website, didn't see any listing for the case.
Anybody know of a source for similar cases?
- Jerry KF6VB
|
Re: uBITX V6 Specifications.
Earl,
That should get you close to 48hours depending on SSB vs CW operation.? One caution with CW on the ?BITX, the selectivity of the rig is 2.7kHz (a standard SSB value), so you might want to add an audio filter to give better discrimination with CW.? Should not add a lot of power drain on receive.? I do not operate CW, so I would look to others for a filter recommendation.
I will verify the receive and transmit current values on Friday.
73
Evan
AC9TU
|
Re: technical question about filter capacitors
Walmart has clear plastic cases of 24 of those jars for hobby use. Here is a pix of one at the bottom of this page..
Earl Cox? KB5UEW? Reply or E-mail me at:? kb5uew@...
On Tuesday, May 4, 2021, 08:04:19 AM MDT, Jack, W8TEE via groups.io <jjpurdum@...> wrote:
Good idea. I typically take one jar and mount all of the caps/resistors of that value on the board at one time, then move on to the next value. As a result, I never have more than one jar open at a time. Also, they hang on the wall on a board and I wouldn't be able to read their values if the jar is labeled. However, if you store them on a shelf, or have a way to store them "laying on their side", your approach is more bullet proof.
Jack, W8TEE
On Tuesday, May 4, 2021, 7:52:16 AM EDT, Bill Cromwell <wrcromwell@...> wrote:
Hello Jack,
The only trouble with those labels is putting them on the
interchangeable lid. If it is possible for them to be swapped it *will*
happen. You are welcome to ask me how I know this. I recommend placing
the label on the jar.
73,
Bill KU8H
bark less - wag more
On 5/3/21 10:48 PM, Jack, W8TEE via groups.io wrote: > Arv: > > I bought a pack of small plastic cosmetic sample jars (eBay > #151829253060) and placed caps or resistors in them. > Inline image > > I then used an small Avery peel-off label, wrote its value on the > label and stuck it on the lid. I should have stopped there, but went > on to put small Velcro pieces on the back and then mounted a board on > the wall vertically and placed a long strip of Velcro on it and stuck > the jars to it. Somebody here didn't think it looked all that cool... > > Jack, W8TEE > > On Monday, May 3, 2021, 4:45:20 PM EDT, Arv Evans > < arvid.evans@...> wrote: > > > Gerard > > I'm probably wrong but maybe there are no markings on 805 and smaller > SMD capacitors because only a very few of us would be able to read the > writing.? Possibly something new and radical like a series of colored dots > would work, but still problematic for us ancient people. > > I have a small isolated-tip tweezer with flexible test probe type > leads and > banana plug connection to a capacitor meter.? Once I got used to the > equipment this lets me spread a handful of SMD components on a plastic > serving tray and quickly measure anything that looks like a capacitor. > Also works for resistors, and other measurable components. > These are then dropped in a fold of paper in order of value. > With a little practice this becomes second-nature and supports quick > sorting and easy circuit board assembly.? Measure the value with the > tweezer tips open, then measure again with the component held in the > tweezer.? Difference is actual component value with stray capacitance > factored out. > > image.png > > <> > > > <> > > Arv > _._ > > > On Mon, May 3, 2021 at 1:47 PM Gerard < kabupos@... > <mailto: kabupos@...>> wrote: > >? ? One thing that is always annoying is that the value of a SMD >? ? capacitor is almost never indicated. >? ? I don¡¯t understand why manufacturers don¡¯t put a mark on the >? ? capacitors , when they do it on resistors. That¡¯s probably a cost. >? ? I put a video on it to find the value without desolding, but you >? ? have to be equipped >? ? And not sure his method work on very low capacitors. > >? ? (18) How to test or measure SMD capacitors on the PCB / on circuit >? ? measurement free electronics training - YouTube >? ? <> > >? ? cdt > > > -- > Jack, W8TEE >
--
Jack, W8TEE
|
Re: uBITX V6 Specifications.
SSB, CW will be most of the time. I have not dived into digital yet. I am looking at 12V, 24AH. I can achieve that in a case of about 5 1/4" X 4" X 3 1/4" weighing a little over 3 lbs.
Earl Cox? KB5UEW? Reply or E-mail me at:? kb5uew@...
On Tuesday, May 4, 2021, 08:39:25 AM MDT, Evan Hand <elhandjr@...> wrote:
Earl,
I will verify when I get to my rig.? Until then, what mode will you be using?? SSB voice, vs CW, vs digital modes makes a difference.? If digital then I would estimate that you need 720mah and CW at slightly less than that.? SSB would have even lower requirements, most likely 50% of digital mode.? That means for 48 hours of continuous operation you would need a 34.5ah battery for digital and 18ah for SSB.? That would be a large battery.? Maybe look into a solar panel as a part of the power scheme.
Please check my math before you commit to a battery.
73
Evan
AC9TU
|
Re: uBITX V6 Specifications.
Earl,
I will verify when I get to my rig.? Until then, what mode will you be using?? SSB voice, vs CW, vs digital modes makes a difference.? If digital then I would estimate that you need 720mah and CW at slightly less than that.? SSB would have even lower requirements, most likely 50% of digital mode.? That means for 48 hours of continuous operation you would need a 34.5ah battery for digital and 18ah for SSB.? That would be a large battery.? Maybe look into a solar panel as a part of the power scheme.
Please check my math before you commit to a battery.
73
Evan
AC9TU
|
Re: technical question about filter capacitors
Good idea. I typically take one jar and mount all of the caps/resistors of that value on the board at one time, then move on to the next value. As a result, I never have more than one jar open at a time. Also, they hang on the wall on a board and I wouldn't be able to read their values if the jar is labeled. However, if you store them on a shelf, or have a way to store them "laying on their side", your approach is more bullet proof.
Jack, W8TEE
On Tuesday, May 4, 2021, 7:52:16 AM EDT, Bill Cromwell <wrcromwell@...> wrote:
Hello Jack,
The only trouble with those labels is putting them on the
interchangeable lid. If it is possible for them to be swapped it *will*
happen. You are welcome to ask me how I know this. I recommend placing
the label on the jar.
73,
Bill KU8H
bark less - wag more
On 5/3/21 10:48 PM, Jack, W8TEE via groups.io wrote: > Arv: > > I bought a pack of small plastic cosmetic sample jars (eBay > #151829253060) and placed caps or resistors in them. > Inline image > > I then used an small Avery peel-off label, wrote its value on the > label and stuck it on the lid. I should have stopped there, but went > on to put small Velcro pieces on the back and then mounted a board on > the wall vertically and placed a long strip of Velcro on it and stuck > the jars to it. Somebody here didn't think it looked all that cool... > > Jack, W8TEE > > On Monday, May 3, 2021, 4:45:20 PM EDT, Arv Evans > < arvid.evans@...> wrote: > > > Gerard > > I'm probably wrong but maybe there are no markings on 805 and smaller > SMD capacitors because only a very few of us would be able to read the > writing.? Possibly something new and radical like a series of colored dots > would work, but still problematic for us ancient people. > > I have a small isolated-tip tweezer with flexible test probe type > leads and > banana plug connection to a capacitor meter.? Once I got used to the > equipment this lets me spread a handful of SMD components on a plastic > serving tray and quickly measure anything that looks like a capacitor. > Also works for resistors, and other measurable components. > These are then dropped in a fold of paper in order of value. > With a little practice this becomes second-nature and supports quick > sorting and easy circuit board assembly.? Measure the value with the > tweezer tips open, then measure again with the component held in the > tweezer.? Difference is actual component value with stray capacitance > factored out. > > image.png > > <> > > > <> > > Arv > _._ > > > On Mon, May 3, 2021 at 1:47 PM Gerard < kabupos@... > <mailto: kabupos@...>> wrote: > >? ? One thing that is always annoying is that the value of a SMD >? ? capacitor is almost never indicated. >? ? I don¡¯t understand why manufacturers don¡¯t put a mark on the >? ? capacitors , when they do it on resistors. That¡¯s probably a cost. >? ? I put a video on it to find the value without desolding, but you >? ? have to be equipped >? ? And not sure his method work on very low capacitors. > >? ? (18) How to test or measure SMD capacitors on the PCB / on circuit >? ? measurement free electronics training - YouTube >? ? <> > >? ? cdt > > > -- > Jack, W8TEE >
-- Jack, W8TEE
|
Gerard
John KG9DK
