From: invalid@invalid.invalid
"Bill Sloman" wrote in message news:10ero
i$3o5c0$3@dont-email.me...
> On 10/11/2025 3:21 am, Edward Rawde wrote:
>> "Bill Sloman" wrote in message news:10
pf02$33ucd$1@dont-email.me...
>>> On 9/11/2025 4:36 am, Edward Rawde wrote:
>>>> "Bill Sloman" wrote in message news:
0emofm$2cnh3$2@dont-email.me...
>>>>> On 8/11/2025 7:44 am, Liz Tuddenham wrote:
>>>>>> Bill Sloman wrote:
>>>>>>
>>>>>>> On 8/11/2025 1:46 am, Liz Tuddenham wrote:
>>>>>>>> Bill Sloman wrote:
>>>>>>>>
>>>>>>>>> On 7/11/2025 9:24 pm, Liz Tuddenham wrote:
>>>>>>>>>> Bill Sloman wrote:
>>>>>>>>>>
>>>>>>>>>>> On 7/11/2025 10:41 am, john larkin wrote:
>>>>>>>>>> [...]>
>>>>>>>>>>>> A real inductor is a nightmare. Especially a long solenoid. Every
turn
>>>>>>>>>>>> inductively couples to every other turn with all possible coupling
>>>>>>>>>>>> coefficients. Distributed capacitances will be similarly complex.
>>>>>>>>>>>
>>>>>>>>>>> This is ignorant nonsense.
>>>>>>>>>>
>>>>>>>>>> I suspect the ignorance is yours.
>>>>>>>>>>
>>>>>>>>>> I worked for a company that built its reputation on the R.F.
inductors
>>>>>>>>>> it designed; these factors were among the many problems they
tackled.
>>>>>>>>>
>>>>>>>>> Probably not very well.
>>>>>>>>
>>>>>>>> What makes you say that about a leading radio company that I haven't
>>>>>>>> even identified.
>>>>>>>
>>>>>>> I spent 22 years in England in the high tech end of the UK electronic
>>>>>>> business, and the understanding of the wound components they used was
>>>>>>> never impressive.
>>>>>>
>>>>>> Just because the company you worked for didn't understand inductors, it
>>>>>> doesn't exclude the possibility that other companies did understand
>>>>>> them.
>>>>>
>>>>> I spent three years at EMI Central Research. Some of their emplpoyees
did get stuff wrong, but they were very high level
>>>>> misunderstandings.
>>>>> I got the staff briefing on their nuclear magnetic resonance imaging
system, and asked them why they weren't using
>>>>> super-conducting magnets, and got told that that was a naive question.
>>>>>
>>>>>>>>> The English language text books I could find ...
>>>>>>>>
>>>>>>>> What is the relevance of that?
>>>>>>>
>>>>>>> It makes a point about the local culture. Kibble and Rayner's "Coaxial
>>>>>>> AC Bridges" had some great stuff about wound components, but
>>>>>>> interwinding capacitance was treated pretty superficially.
>>>>>>
>>>>>> How does that support your contention that an unnamed company, that
>>>>>> built its reputation on the excellence of its R.F. inductors, didn't
>>>>>> design them very well?
>>>>>
>>>>> John Larkin doesn't understand what he is doing all that well,but if you
keep experimenting and testing for long enough you
>>>>> can
>>>>> come up with pretty impressive products. Not as good as they could be -
but quite good enough.
>>>>
>>>> You don't seem to be interested in providing information which would lead
to better products Bill.
>>>> You seem to be much more interested in telling other people how stupid
they are
>>>> for only designing products which are "quite good enough".
>>>>
>>>> The circuit below is not good enough in my view but you didn't seem to be
able to handle any
>>>> criticism of it some time ago.
>>>
>>> Since it comes from the early part of a very long thread, and since I
subsequently posted variations which performed a whole lot
>>> better, I seem to have been able to handle well-informed criticism pretty
well.
>>>
>>> JM was a whole lot more helpful than you were.You did post a variation of
one of his circuits which managed to use eight
>>> transistors in the adjustable gain section - which he promptly cut down to
four, and I subsequently increased to five which got
>>> us
>>> up to 150db suppression of the higher harmonics
>>>
>>>> What are Audiophiles going to think when they have to wait a whole second
for the output level to stabilize?
>>>
>>> They won't care. It is a reference sine wave generator.
>>>
>>>> Not to mention the barely 60dB harmonic performance. These factors show
that it is not well designed.
>>>
>>> The design did need improvement, and it got it. I'd posted it as a first
try at an alternative to the FET gain control element.
>>> 60dB harmonic suppression is actually pretty good, but the FET approach
could do much better. JM changed my design to get it to
>>> do
>>> much better.
>>
>>> You didn't like his tantalum bead capacitors and found another way of
reducing ripple feed-through, which he was able to
>>> simplify.
>>
>> I don't recall anything about tantalum bead capacitors but it's not
important.
>
> It isn't. But the fact that you can't recall that detail is revealing.
The fact that you haven't quoted the post where this detail was mentioned is
also revealing.
Either do so or shut up.
>
>> I can remember a few of them going pop when the prototype had them in the
wrong way but that's a different story.
>
> It was even worse when they didn't go pop. It once took us a day at EMI
Central Research to find out why our prototype phased
> array ultrasound machine wasn't focussing, and it turned out to be a wrongly
mounted tantalum bead capacitor messing up a rail
> voltage in the hyperbolic function generator. That was a day when we were
supposed to be showing off the machine. I can't
> complain - I got to put together a second version of the protoytpe with
everything on printed circuit cards, which was reliable
> enough for us to ship around the UK as a clinical trials machine. One of the
printed circuit boards was a bit too tightly packed -
> I'd wanted to split it into two but my boss was correctly convinced that we
could squeeze it all onto one board, but it did take a
> lot of tedious fiddling with the layout. Laying out two boards
> would have been cheaper - we had to pay for all that tedious fiddling.
> --
> Bill Sloman, Sydney
>
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