On Monday, November 15, 2021 at 7:49:48 AM UTC-8, jla...@highlandsniptechnology.com wrote:> On Mon, 15 Nov 2021 23:07:34 +1100, Chris Jones > <lugn...@spam.yahoo.com> wrote: > > >On 15/11/2021 16:34, whit3rd wrote:> >> When mailorder is slow, and you have a triangle file and carbon comp > >> resistor in play, it's time to declare armistice or maybe even peace. > >> > >> Remember, after filing the notch, to use some nail polish for > >> sealing that surface... or job it out to a cosmetology shop.> >Barbarian, using a triangle file, think of the mechanical stress > >concentration begging it to snap in half. Use a round chainsaw > >sharpening file or round needle file at least! I'd even consider > >drilling a few small holes part way through it would be more humane.> I haven't seen a carbon comp resistor in years.Lucky you! They were employed as trimmers by none other than Seymour Cray, back in the dark ages of RTL, before computers could Spice faster than techs could wirewrap.
juggling parts
Started by ●November 14, 2021
Reply by ●November 16, 20212021-11-16
Reply by ●November 16, 20212021-11-16
On a sunny day (Tue, 16 Nov 2021 19:07:59 +0100) it happened Jeroen Belleman <jeroen@nospam.please> wrote in <sn0s1v$1dfr$1@gioia.aioe.org>:>On 2021-11-16 16:35, jlarkin@highlandsniptechnology.com wrote: >> On Tue, 16 Nov 2021 22:42:52 +1100, Chris Jones >> <lugnut808@spam.yahoo.com> wrote: >> >>> On 16/11/2021 02:49, jlarkin@highlandsniptechnology.com wrote: >>>> On Mon, 15 Nov 2021 23:07:34 +1100, Chris Jones >>>> <lugnut808@spam.yahoo.com> wrote: >>>> >>>>> On 15/11/2021 16:34, whit3rd wrote: >>>>>> On Sunday, November 14, 2021 at 2:14:53 PM UTC-8, TTman wrote: >>>>>>> On 14/11/2021 18:27, jla...@highlandsniptechnology.com wrote: >>>>>> >>>>>>>> I have space on this one for a few more 0603s. It's inefficient to >>>>>>>> load a reel onto the pick-and-place just for one resistor. >>>>>> >>>>>>> Pots are your enemy... >>>>>> >>>>>> When mailorder is slow, and you have a triangle file and carbon comp >>>>>> resistor in play, it's time to declare armistice or maybe even peace. >>>>>> >>>>>> Remember, after filing the notch, to use some nail polish for >>>>>> sealing that surface... or job it out to a cosmetology shop. >>>>>> >>>>> >>>>> Barbarian, using a triangle file, think of the mechanical stress >>>>> concentration begging it to snap in half. Use a round chainsaw >>>>> sharpening file or round needle file at least! I'd even consider >>>>> drilling a few small holes part way through it would be more humane. >>>>> >>>> >>>> I haven't seen a carbon comp resistor in years. >>> >>> The only good use I can think of for them is absorbing large pulses of >>> energy in a very short time, as the heat would be deposited throughout a >>> larger mass than the mass of a thin or thick film. >>> >> >> AoE X-chapters, p 26, has some great data about exploding various >> resistors. The carbon comps win for short pulses, below about 1 >> millisecond. >> >> I always assumed that 50 ohm cc's were best for high frequency >> termination, but the cheap carbon film resistors are about as good. >> Surface-mount thick films are better than either... less lead >> inductance. >> >> >> > >I've tried several low-value resistors for high-frequency matching pads >and terminations. SMD 1206 resistors tend to be too capacitive, and the >similar-sized MELFs are too inductive. It's easier to gimmick the MELFs, >so that's what I tend to choose when it matters. > >Jeroen Bellemanhttp://panteltje.com/pub/power_50_Ohm_termination_IXIMG_0744.JPG
Reply by ●November 16, 20212021-11-16
On Tuesday, November 16, 2021 at 10:08:05 AM UTC-8, Jeroen Belleman wrote:> I've tried several low-value resistors for high-frequency matching pads > and terminations. SMD 1206 resistors tend to be too capacitive, and the > similar-sized MELFs are too inductive. It's easier to gimmick the MELFs, > so that's what I tend to choose when it matters.The biggest factor often ends up being the PCB stackup. Assuming you clear the copper underneath, a pair of 100-ohm 0603 resistors in parallel is hard to beat. -- john, KE5FX
Reply by ●November 16, 20212021-11-16
On 11/16/2021 1:59 PM, Jan Panteltje wrote:> On a sunny day (Tue, 16 Nov 2021 19:07:59 +0100) it happened Jeroen Belleman > <jeroen@nospam.please> wrote in <sn0s1v$1dfr$1@gioia.aioe.org>: > >> On 2021-11-16 16:35, jlarkin@highlandsniptechnology.com wrote: >>> On Tue, 16 Nov 2021 22:42:52 +1100, Chris Jones >>> <lugnut808@spam.yahoo.com> wrote: >>> >>>> On 16/11/2021 02:49, jlarkin@highlandsniptechnology.com wrote: >>>>> On Mon, 15 Nov 2021 23:07:34 +1100, Chris Jones >>>>> <lugnut808@spam.yahoo.com> wrote: >>>>> >>>>>> On 15/11/2021 16:34, whit3rd wrote: >>>>>>> On Sunday, November 14, 2021 at 2:14:53 PM UTC-8, TTman wrote: >>>>>>>> On 14/11/2021 18:27, jla...@highlandsniptechnology.com wrote: >>>>>>> >>>>>>>>> I have space on this one for a few more 0603s. It's inefficient to >>>>>>>>> load a reel onto the pick-and-place just for one resistor. >>>>>>> >>>>>>>> Pots are your enemy... >>>>>>> >>>>>>> When mailorder is slow, and you have a triangle file and carbon comp >>>>>>> resistor in play, it's time to declare armistice or maybe even peace. >>>>>>> >>>>>>> Remember, after filing the notch, to use some nail polish for >>>>>>> sealing that surface... or job it out to a cosmetology shop. >>>>>>> >>>>>> >>>>>> Barbarian, using a triangle file, think of the mechanical stress >>>>>> concentration begging it to snap in half. Use a round chainsaw >>>>>> sharpening file or round needle file at least! I'd even consider >>>>>> drilling a few small holes part way through it would be more humane. >>>>>> >>>>> >>>>> I haven't seen a carbon comp resistor in years. >>>> >>>> The only good use I can think of for them is absorbing large pulses of >>>> energy in a very short time, as the heat would be deposited throughout a >>>> larger mass than the mass of a thin or thick film. >>>> >>> >>> AoE X-chapters, p 26, has some great data about exploding various >>> resistors. The carbon comps win for short pulses, below about 1 >>> millisecond. >>> >>> I always assumed that 50 ohm cc's were best for high frequency >>> termination, but the cheap carbon film resistors are about as good. >>> Surface-mount thick films are better than either... less lead >>> inductance. >>> >>> >>> >> >> I've tried several low-value resistors for high-frequency matching pads >> and terminations. SMD 1206 resistors tend to be too capacitive, and the >> similar-sized MELFs are too inductive. It's easier to gimmick the MELFs, >> so that's what I tend to choose when it matters. >> >> Jeroen Belleman > > http://panteltje.com/pub/power_50_Ohm_termination_IXIMG_0744.JPG >Yow! Look at the inductance in that shield connecting wire!
Reply by ●November 16, 20212021-11-16
On a sunny day (Tue, 16 Nov 2021 15:01:47 -0600) it happened John S <Sophi.2@invalid.org> wrote in <sn167v$851$2@dont-email.me>:>On 11/16/2021 1:59 PM, Jan Panteltje wrote: >> On a sunny day (Tue, 16 Nov 2021 19:07:59 +0100) it happened Jeroen Belleman >> <jeroen@nospam.please> wrote in <sn0s1v$1dfr$1@gioia.aioe.org>: >> >>> On 2021-11-16 16:35, jlarkin@highlandsniptechnology.com wrote: >>>> On Tue, 16 Nov 2021 22:42:52 +1100, Chris Jones >>>> <lugnut808@spam.yahoo.com> wrote: >>>> >>>>> On 16/11/2021 02:49, jlarkin@highlandsniptechnology.com wrote: >>>>>> On Mon, 15 Nov 2021 23:07:34 +1100, Chris Jones >>>>>> <lugnut808@spam.yahoo.com> wrote: >>>>>> >>>>>>> On 15/11/2021 16:34, whit3rd wrote: >>>>>>>> On Sunday, November 14, 2021 at 2:14:53 PM UTC-8, TTman wrote: >>>>>>>>> On 14/11/2021 18:27, jla...@highlandsniptechnology.com wrote: >>>>>>>> >>>>>>>>>> I have space on this one for a few more 0603s. It's inefficient to >>>>>>>>>> load a reel onto the pick-and-place just for one resistor. >>>>>>>> >>>>>>>>> Pots are your enemy... >>>>>>>> >>>>>>>> When mailorder is slow, and you have a triangle file and carbon comp >>>>>>>> resistor in play, it's time to declare armistice or maybe even peace. >>>>>>>> >>>>>>>> Remember, after filing the notch, to use some nail polish for >>>>>>>> sealing that surface... or job it out to a cosmetology shop. >>>>>>>> >>>>>>> >>>>>>> Barbarian, using a triangle file, think of the mechanical stress >>>>>>> concentration begging it to snap in half. Use a round chainsaw >>>>>>> sharpening file or round needle file at least! I'd even consider >>>>>>> drilling a few small holes part way through it would be more humane. >>>>>>> >>>>>> >>>>>> I haven't seen a carbon comp resistor in years. >>>>> >>>>> The only good use I can think of for them is absorbing large pulses of >>>>> energy in a very short time, as the heat would be deposited throughout a >>>>> larger mass than the mass of a thin or thick film. >>>>> >>>> >>>> AoE X-chapters, p 26, has some great data about exploding various >>>> resistors. The carbon comps win for short pulses, below about 1 >>>> millisecond. >>>> >>>> I always assumed that 50 ohm cc's were best for high frequency >>>> termination, but the cheap carbon film resistors are about as good. >>>> Surface-mount thick films are better than either... less lead >>>> inductance. >>>> >>>> >>>> >>> >>> I've tried several low-value resistors for high-frequency matching pads >>> and terminations. SMD 1206 resistors tend to be too capacitive, and the >>> similar-sized MELFs are too inductive. It's easier to gimmick the MELFs, >>> so that's what I tend to choose when it matters. >>> >>> Jeroen Belleman >> >> http://panteltje.com/pub/power_50_Ohm_termination_IXIMG_0744.JPG >> > >Yow! Look at the inductance in that shield connecting wire!Na, SWR OK on 2.4 GHz, wavelength is about 12.5 cm could solder it a bit shorter, OK. Spectrian 75W linear amp: http://panteltje.com/pub/spectrian_2.4-GHz_linear_top_view_IMG_4576.JPG
Reply by ●November 16, 20212021-11-16
jlarkin@highlandsniptechnology.com wrote:> On Tue, 16 Nov 2021 11:23:59 -0500, legg <legg@nospam.magma.ca> wrote: > >> On Tue, 16 Nov 2021 07:40:30 -0800, jlarkin@highlandsniptechnology.com >> wrote: >> >>> On Tue, 16 Nov 2021 08:56:07 -0500, legg <legg@nospam.magma.ca> wrote: >>> >>>> On Sun, 14 Nov 2021 10:27:20 -0800, jlarkin@highlandsniptechnology.com >>>> wrote: >>>> >>>> <snip> >>>>>> What I do not get is: you sell expensive things in low quantity and try to save on a trimpot? >>>>> >>>>> Trimpots are expensive and need manual turning. DACs are automated and >>>>> can have cal factors stored in cal tables. I'm using 16-bit DACs and >>>>> there are no 16-bit trimpots. >>>>> >>>>> Some of my customers absolutely forbid trimpots, which I think is >>>>> extreme. Once in a while they make sense. They say that if there's a >>>>> pot, their techs will turn it. >>>>> >>>> >>>> If the tech doesn't have access to the cal table, that DAC's not doing >>>> the work of a trimpot. >>>> >>>> RL >>> >>> It's preventing him from mucking with something he doesn't understand >>> and doesn't have the equipment to calibrate. Besides, some products >>> have a hundred cal factors. >>> >>> If something in a signal chain is broken, twiddling pots will break >>> more things. We rarely use trimpots, and then only to tweak gain in >>> GHz-range amplifiers. >> >> If it's not meant to be adjusted, then sot fixed parts are more a >> suitable analog comparison. A trimpot would be an unjustified >> vulnerability, simply from a reliability and cost standpoint. >> >> I'm finding that that programmable part are increasingly dominant in >> non-repairability situations, so It rankles when the equation is >> made to an impractical analog equivalent. >> >> RL > > We do polynomial calibrations all the time. Try that with trimpots! > > > >Exact used to make an arbitrary waveform generator with about 25 dial pots on the front panel, one per sample point. ;) Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics Briarcliff Manor NY 10510 http://electrooptical.net http://hobbs-eo.com
Reply by ●November 16, 20212021-11-16
On 2021-11-16 20:59, Jan Panteltje wrote:> On a sunny day (Tue, 16 Nov 2021 19:07:59 +0100) it happened Jeroen Belleman > <jeroen@nospam.please> wrote in <sn0s1v$1dfr$1@gioia.aioe.org>: > >> On 2021-11-16 16:35, jlarkin@highlandsniptechnology.com wrote: >>> On Tue, 16 Nov 2021 22:42:52 +1100, Chris Jones >>> <lugnut808@spam.yahoo.com> wrote: >>> >>>> On 16/11/2021 02:49, jlarkin@highlandsniptechnology.com wrote: >>>>> On Mon, 15 Nov 2021 23:07:34 +1100, Chris Jones >>>>> <lugnut808@spam.yahoo.com> wrote: >>>>> >>>>>> On 15/11/2021 16:34, whit3rd wrote: >>>>>>> On Sunday, November 14, 2021 at 2:14:53 PM UTC-8, TTman wrote: >>>>>>>> On 14/11/2021 18:27, jla...@highlandsniptechnology.com wrote: >>>>>>> >>>>>>>>> I have space on this one for a few more 0603s. It's inefficient to >>>>>>>>> load a reel onto the pick-and-place just for one resistor. >>>>>>> >>>>>>>> Pots are your enemy... >>>>>>> >>>>>>> When mailorder is slow, and you have a triangle file and carbon comp >>>>>>> resistor in play, it's time to declare armistice or maybe even peace. >>>>>>> >>>>>>> Remember, after filing the notch, to use some nail polish for >>>>>>> sealing that surface... or job it out to a cosmetology shop. >>>>>>> >>>>>> >>>>>> Barbarian, using a triangle file, think of the mechanical stress >>>>>> concentration begging it to snap in half. Use a round chainsaw >>>>>> sharpening file or round needle file at least! I'd even consider >>>>>> drilling a few small holes part way through it would be more humane. >>>>>> >>>>> >>>>> I haven't seen a carbon comp resistor in years. >>>> >>>> The only good use I can think of for them is absorbing large pulses of >>>> energy in a very short time, as the heat would be deposited throughout a >>>> larger mass than the mass of a thin or thick film. >>>> >>> >>> AoE X-chapters, p 26, has some great data about exploding various >>> resistors. The carbon comps win for short pulses, below about 1 >>> millisecond. >>> >>> I always assumed that 50 ohm cc's were best for high frequency >>> termination, but the cheap carbon film resistors are about as good. >>> Surface-mount thick films are better than either... less lead >>> inductance. >>> >>> >>> >> >> I've tried several low-value resistors for high-frequency matching pads >> and terminations. SMD 1206 resistors tend to be too capacitive, and the >> similar-sized MELFs are too inductive. It's easier to gimmick the MELFs, >> so that's what I tend to choose when it matters. >> >> Jeroen Belleman > > http://panteltje.com/pub/power_50_Ohm_termination_IXIMG_0744.JPG >That wouldn't fly with me. :-) Jeroen Belleman
Reply by ●November 16, 20212021-11-16
legg wrote:> On Tue, 16 Nov 2021 07:40:30 -0800, jlarkin@highlandsniptechnology.com > wrote: > >> On Tue, 16 Nov 2021 08:56:07 -0500, legg <legg@nospam.magma.ca> wrote: >> >>> On Sun, 14 Nov 2021 10:27:20 -0800, jlarkin@highlandsniptechnology.com >>> wrote: >>> >>> <snip> >>>>> What I do not get is: you sell expensive things in low quantity and try to save on a trimpot? >>>> >>>> Trimpots are expensive and need manual turning. DACs are automated and >>>> can have cal factors stored in cal tables. I'm using 16-bit DACs and >>>> there are no 16-bit trimpots. >>>> >>>> Some of my customers absolutely forbid trimpots, which I think is >>>> extreme. Once in a while they make sense. They say that if there's a >>>> pot, their techs will turn it. >>>> >>> >>> If the tech doesn't have access to the cal table, that DAC's not doing >>> the work of a trimpot. >>> >>> RL >> >> It's preventing him from mucking with something he doesn't understand >> and doesn't have the equipment to calibrate. Besides, some products >> have a hundred cal factors. >> >> If something in a signal chain is broken, twiddling pots will break >> more things. We rarely use trimpots, and then only to tweak gain in >> GHz-range amplifiers. > > If it's not meant to be adjusted, then sot fixed parts are more a > suitable analog comparison. A trimpot would be an unjustified > vulnerability, simply from a reliability and cost standpoint. > > I'm finding that that programmable part are increasingly dominant in > non-repairability situations, so It rankles when the equation is > made to an impractical analog equivalent. > > RL >In TIAs, it's often helpful to use an RC lead-lag network to compensate for the parallel capacitance of a high-value feedback resistor. A trimpot is good medicine for that. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics Briarcliff Manor NY 10510 http://electrooptical.net http://hobbs-eo.com
Reply by ●November 16, 20212021-11-16
On Tue, 16 Nov 2021 08:49:51 -0800, jlarkin@highlandsniptechnology.com wrote:>On Tue, 16 Nov 2021 11:23:59 -0500, legg <legg@nospam.magma.ca> wrote: > >>On Tue, 16 Nov 2021 07:40:30 -0800, jlarkin@highlandsniptechnology.com >>wrote: >> >>>On Tue, 16 Nov 2021 08:56:07 -0500, legg <legg@nospam.magma.ca> wrote: >>> >>>>On Sun, 14 Nov 2021 10:27:20 -0800, jlarkin@highlandsniptechnology.com >>>>wrote: >>>> >>>><snip> >>>>>>What I do not get is: you sell expensive things in low quantity and try to save on a trimpot? >>>>> >>>>>Trimpots are expensive and need manual turning. DACs are automated and >>>>>can have cal factors stored in cal tables. I'm using 16-bit DACs and >>>>>there are no 16-bit trimpots. >>>>> >>>>>Some of my customers absolutely forbid trimpots, which I think is >>>>>extreme. Once in a while they make sense. They say that if there's a >>>>>pot, their techs will turn it. >>>>> >>>> >>>>If the tech doesn't have access to the cal table, that DAC's not doing >>>>the work of a trimpot. >>>> >>>>RL >>> >>>It's preventing him from mucking with something he doesn't understand >>>and doesn't have the equipment to calibrate. Besides, some products >>>have a hundred cal factors. >>> >>>If something in a signal chain is broken, twiddling pots will break >>>more things. We rarely use trimpots, and then only to tweak gain in >>>GHz-range amplifiers. >> >>If it's not meant to be adjusted, then sot fixed parts are more a >>suitable analog comparison. A trimpot would be an unjustified >>vulnerability, simply from a reliability and cost standpoint. >> >>I'm finding that that programmable part are increasingly dominant in >>non-repairability situations, so It rankles when the equation is >>made to an impractical analog equivalent. >> >>RL > >We do polynomial calibrations all the time. Try that with trimpots!Again, not a suitable comparison. Polynomial calibration, for systems that drift under ALL influences . . . better measure them influences! RL
Reply by ●November 16, 20212021-11-16
On Tue, 16 Nov 2021 17:29:04 -0500, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:>jlarkin@highlandsniptechnology.com wrote: >> On Tue, 16 Nov 2021 11:23:59 -0500, legg <legg@nospam.magma.ca> wrote: >> >>> On Tue, 16 Nov 2021 07:40:30 -0800, jlarkin@highlandsniptechnology.com >>> wrote: >>> >>>> On Tue, 16 Nov 2021 08:56:07 -0500, legg <legg@nospam.magma.ca> wrote: >>>> >>>>> On Sun, 14 Nov 2021 10:27:20 -0800, jlarkin@highlandsniptechnology.com >>>>> wrote: >>>>> >>>>> <snip> >>>>>>> What I do not get is: you sell expensive things in low quantity and try to save on a trimpot? >>>>>> >>>>>> Trimpots are expensive and need manual turning. DACs are automated and >>>>>> can have cal factors stored in cal tables. I'm using 16-bit DACs and >>>>>> there are no 16-bit trimpots. >>>>>> >>>>>> Some of my customers absolutely forbid trimpots, which I think is >>>>>> extreme. Once in a while they make sense. They say that if there's a >>>>>> pot, their techs will turn it. >>>>>> >>>>> >>>>> If the tech doesn't have access to the cal table, that DAC's not doing >>>>> the work of a trimpot. >>>>> >>>>> RL >>>> >>>> It's preventing him from mucking with something he doesn't understand >>>> and doesn't have the equipment to calibrate. Besides, some products >>>> have a hundred cal factors. >>>> >>>> If something in a signal chain is broken, twiddling pots will break >>>> more things. We rarely use trimpots, and then only to tweak gain in >>>> GHz-range amplifiers. >>> >>> If it's not meant to be adjusted, then sot fixed parts are more a >>> suitable analog comparison. A trimpot would be an unjustified >>> vulnerability, simply from a reliability and cost standpoint. >>> >>> I'm finding that that programmable part are increasingly dominant in >>> non-repairability situations, so It rankles when the equation is >>> made to an impractical analog equivalent. >>> >>> RL >> >> We do polynomial calibrations all the time. Try that with trimpots! >> >> >> >> >Exact used to make an arbitrary waveform generator with about 25 dial >pots on the front panel, one per sample point. ;) > >Cheers > >Phil HobbsAnd I think they are extinct! -- If a man will begin with certainties, he shall end with doubts, but if he will be content to begin with doubts he shall end in certainties. Francis Bacon
