Reply by Joseph Gwinn●September 13, 20182018-09-13
On Sep 13, 2018, John Larkin wrote
(in article<ratkpdd8tm9gdtnqvmup0ip6rrjlmritjk@4ax.com>):
> On Thu, 13 Sep 2018 01:32:15 -0700 (PDT), whit3rd<whit3rd@gmail.com>
> wrote:
>
> > On Wednesday, September 12, 2018 at 8:04:55 PM UTC-7, bill....@ieee.org
> > wrote:
> > > On Thursday, September 13, 2018 at 6:09:16 AM UTC+10, John Larkin wrote:
> >
> > > > Spark gaps can be impressive!
> > >
> > > But erosive. And the glow-to-arc transition takes closer a microsecond
> > > than a picosecond.
> >
> > Erosion is real; there's a molybdenum electrode with a few grams missing
> > in my junk box. The platinum button in a spark plug, though, lasts quite a
> > while
> > with modest currents. Probably the metal ions just aren't part of that kind
> > of arc.
>
> Does anybody know what this is?
>
> <https://www.dropbox.com/s/np4s7ifgg5f4gbz/DSC01841.JPG?raw=1>
>
> <https://www.dropbox.com/s/6ckipx3z8v4nf72/DSC01844.JPG?raw=1>
>
> Spark gap? Waveguide T/R switch?
I’d say HV spark gap.
It does not look like it world work as a T/R switch - wrong shape, although I
suppose it could be between two pillars transverse to a rectangular waveguide
(shorting the long walls).
Joe Gwinn
Reply by ●September 13, 20182018-09-13
>John Larkin wrote
>>>>>>But most CCROs are probably used as
>>>>>>bandpass filters.
>>>>>>
>>>>>>http://www.mpdigest.com/2017/01/23/ceramic-resonator-band-pass-filter/
>>>>>
>>>>>
>>>>>
>>>>>Yes of course, those ceramic filters, or should I say SAW filters, are everywhere,
>>>>>for example in TVs as IF filter.
>>>
>>>>A CCRO is different from a SAW. And different from a mechanically
>>>>resonant ceramic filter. I guess you knew that.
What you probably meant by CCRO is a dielectric resonator based oscillator
https://en.wikipedia.org/wiki/Dielectric_resonator
The link you pointed to says ceramic-resonator-band-pass-filter
CCRO filter stands for
Closed Circuit Reverse Osmosis filter
something entirely different.
Yes dielectric resonators are the same as the 'pucks' in the picture I showed earlier:
http://panteltje.com/pub/5_dollar_LNB_PCB_IMG_3582.GIF
People can tune those (increase frequency) by removing something of the material.
or add something to decrease frequency.
Those are not very stable compared to a crystal controlled PLL.
>>No, there is no motion. Each tube is a shorted coaxial transmission
>>line. The dielectric constant of the ceramic is so high that the line
>>is short relative to the round-trip frequency. In the filter, the CCRs
>>are coupled somehow, classic multiple-resonator math.
dielectric resonators!
Anyways, now we know what we talk about.
Reply by ●September 13, 20182018-09-13
<698839253X6D445TD@nospam.org> wrote in
news:pndu81$1l3q$1@gioia.aioe.org:
It is probably one of those fortune telling machines that you have to rotate and then you see the future in it.
google does not know that number, you should tell them.
>On Wednesday, September 12, 2018 at 8:04:55 PM UTC-7, bill....@ieee.org wrote:
>> On Thursday, September 13, 2018 at 6:09:16 AM UTC+10, John Larkin wrote:
>
>> > Spark gaps can be impressive!
>>
>> But erosive. And the glow-to-arc transition takes closer a microsecond than a picosecond.
>
>Erosion is real; there's a molybdenum electrode with a few grams missing
>in my junk box. The platinum button in a spark plug, though, lasts quite a while
>with modest currents. Probably the metal ions just aren't part of that kind of arc.
whit3rd <whit3rd@gmail.com> wrote in news:8c742c2a-2bfb-4e62-aca6-
b37506b44acc@googlegroups.com:
> The platinum button in a spark plug, though, lasts quite a while
> with modest currents.
Buy a set of points for an old V8 chevy OR even a Briggs and Stratton lawn
mower engine. Platinum plated contacts made for the purpose.
Reply by whit3rd●September 13, 20182018-09-13
On Wednesday, September 12, 2018 at 8:04:55 PM UTC-7, bill....@ieee.org wrote:
> On Thursday, September 13, 2018 at 6:09:16 AM UTC+10, John Larkin wrote:
> > Spark gaps can be impressive!
>
> But erosive. And the glow-to-arc transition takes closer a microsecond than a picosecond.
Erosion is real; there's a molybdenum electrode with a few grams missing
in my junk box. The platinum button in a spark plug, though, lasts quite a while
with modest currents. Probably the metal ions just aren't part of that kind of arc.
Reply by ●September 13, 20182018-09-13
John Larkin wrote
>CK722 was slow, maybe under 1 MHz, but the data sheets didn't spec it.
>I think it was a nasty alloy-junction part.
It took me half an hour googling to find the Ft of the OC76 online...
Anyways I _do_ remember Philips had OC13 sold as LF transistor (for audio)
and OC44 OC45 as 'IF' transistor for the 455 kHz or so IF amplifiers.
RF GE transistors came later... in the sixties IIRC,
I build a small FM transmitter with just 1 transistor
also using the Cce change with voltage to frequency modulate it.
Not sure that would work with a modern transistor.
The old ones were so sensitive I did something this
+9V
/// |
| dynamic mike (few hundred ohm)
=== |---
| ( |
) ( === tuned to about 100MHz
| ( |
| |------
| c |
b |
| e |
| | |
| /// |
- R-----
That thing was so sensitive you could here a clock ticking over the radio.
The mike changed the Vce a few mV, was enough to get many kHz frequency deviation.
>>>>>But most CCROs are probably used as
>>>>>bandpass filters.
>>>>>
>>>>>http://www.mpdigest.com/2017/01/23/ceramic-resonator-band-pass-filter/
>>>>
>>>>
>>>>
>>>>Yes of course, those ceramic filters, or should I say SAW filters, are everywhere,
>>>>for example in TVs as IF filter.
>>
>>>A CCRO is different from a SAW. And different from a mechanically
>>>resonant ceramic filter. I guess you knew that.
>>
>>No, I do not know everything :-)
>>Looks in that picture like just some ceramic tubes like you add crystals together to make a steep filter..
>>Something vibrates mechanically...
>
>No, there is no motion. Each tube is a shorted coaxial transmission
>line. The dielectric constant of the ceramic is so high that the line
>is short relative to the round-trip frequency. In the filter, the CCRs
>are coupled somehow, classic multiple-resonator math.
Not sure I grab that, will look it up.
>It's fun to TDR one. It looks just like a shorted coax, but the
>impedances are low, 10 ohms maybe, and there is a lot of delay
>relative to the size.
>
>
>>Any papers on that?
>
>Probably stuff from the manufacturers, although they usually work in
>frequency domain. Boring sine waves.
The whole world uses sine waves to commie-nuke-aid....
>>>>Microwave is fun !
>
>Pulses are even more fun!
Yea digital, but even there it is deliberately bandwidth limited,
to get more info over the same link, in the same bandwidth,
that is an art too.
For those who try the laser fusion perhaps... but that did not work out so well either?
Still waiting for usable break even.
Most stuff uses sine waves....
Spectra...
Na yaa, 100 ps is only 10 GHz.... so rise and fall times are much faster
/\ /\
/ \/ \
| |
100 ps period time
| |
50 ps up, 50 ps down
This one works at > 12 GHz...
;-)
>Step-recovery diodes can make sub 100 ps pulses easily. NLTLs can get
>down to rise times in the single digits of ps.
>
>Gain-switched lasers can make optical pulses in the 10s of ps width,
>from fairly slow electrical drive.
>
>>How much power does it deliver?
>
>Spark gaps can be impressive!
Yea, I did that as a kid, when I asked the son of a local radio ham to ask his father to listen for my 'transmitter' I did not get friendly feedback...
'If I ever hear that thing [again?] I will...'
We had a lot of TV interference from things with electric ignition driving past the house, local TV was at about 65 MHz..
Only later did they use screened ignition cables and some measures against RF radiation.