It isn't a coaxial relay, but it is an RF one--controlled impedance all the way. Nice part.
Cheers
Phil Hobbs
-- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 USA +1 845 480 2058 hobbs at electrooptical dot net http://electrooptical.net
Yeah, I should get some of those to test as well. Thanks.
Cheers
Phil Hobbs
-- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 USA +1 845 480 2058 hobbs at electrooptical dot net http://electrooptical.net
e
ell,
o far
ay
Thanks...
that g6k looks like an RF relay :-)
Those are OK for low power. Try switching in the 1 KW to 500 KW RF range with one.
Another that may have what you need. .02pF
summing
IK, bootstrap the unused contacts.
There's a few pF from the SJ to ground
It's shocking how many people throw away 20 or 30 dB in the front end of an very expensive analytical instrument. I've told the story of the FTMS preamp designed by chemists....
All that is inside the V+ bootstrap? Nice. Now you need a world-class Isink.
You could put that on a small board and sell it.
-- John Larkin Highland Technology Inc www.highlandtechnology.com jlarkin at highlandtechnology dot com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom timing and laser controllers Photonics and fiberoptic TTL data links VME analog, thermocouple, LVDT, synchro, tachometer Multichannel arbitrary waveform generators
Too bad that MEMS relays are like fuel cells, always a couple of years away.
-- John Larkin Highland Technology Inc www.highlandtechnology.com jlarkin at highlandtechnology dot com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom timing and laser controllers Photonics and fiberoptic TTL data links VME analog, thermocouple, LVDT, synchro, tachometer Multichannel arbitrary waveform generators
r
Hi Phil, I don't have any relay recommendations, but I was trying to think of how to do it, ?the other way around?.
I just hit me as I was doing something else. So I don?t know if this will help or not. But what about if you put the 50G and 1 G in series and then shorted out the 50G with a relay?
George H.
Maybe Teledyne have something to offer.
--
"For a successful technology, reality must take precedence
over public relations, for nature cannot be fooled."
(Richard Feynman)
George, the 50G resistor will be bypassed by the 0.3 pF relay cap when f>10Hz.
Rgrds Mikko
Big magnet because you need the distance because of capacitance? How about reed switches with a ferrite magnet, or ferrite flux guides on a smaller, stronger magnet? Or ferrite flux guides on a solenoid?
I think ferrite is about 10 relative permittivity. These reed switches are tiny...
Cheers
-- Syd
summing
very
designed
I might actually do that. I have a couple of family members apprenticing at the moment, one in firmware and circuit design, the other in PC layout.
A little box like that, with Amazon fulfilling the orders, might be a good place to start. (Amazon charges 7% of sales, plus 50 cents per cubic foot per month. For small, high-value items that no warehouseman in his right mind would pilfer, that's a gift.)
Cheers
Phil Hobbs
-- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 hobbs at electrooptical dot net http://electrooptical.net
10Hz.
Hmm yeah, dang capacitance.
George H.
As R. V. Jones's colleague put it. (I know you've been reading
*Instruments and Experiences*. Great book.)The problem is that due to the relay capacitance, at frequencies above a couple of kilohertz, that scheme is no different SNR-wise from the plain
1 G by itself. I have to short out the 1G to get rid of its current noise.(A capacitor from the SJ to ground increases the noise gain of the stage, but doesn't contribute noise of its own.)
I could put them in series and use a SPDT to short out one or the other, but then I wouldn't have a well-defined circuit point to bootstrap the coil to, so the AC gain might go all over the place. I suppose I could construct such a point, by using lower value resistors and the other section of the relay to switch a voltage divider appropriately. That would have a good deal more voltage noise than the amplifier, though, and it would be more complicated than just grounding the outer layer of the relay coil.
Cheers
Phil Hobbs
-- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 hobbs at electrooptical dot net http://electrooptical.net
I've use a Reed relay with glass innards in my ham radio station for over a decade. Morse code went over it, tons of dits and dahs, and it had to key tube transmitters which taxes the contact quite a lot. Assuming wear-out I had a spare taped to the inside of the box of my electronics keyer. Never needed that spare.
-- Regards, Joerg http://www.analogconsultants.com/
The ones I tested are G6KU-2G-Y.
The section-to-section capacitance goes from 300 fF to 60 fF when I ground the coil, but the open-contact capacitance only goes from 410 to
200 fF, so I guess the actual open-contact capacitance is about 0.2 pF. That isn't horrible--just the resistors will be in that ballpark.Cheers
Phil Hobbs
-- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 hobbs at electrooptical dot net http://electrooptical.net
Wasn't there a meter from Fluke or some other company that had push rods which then rolled a piece of foil against contact points? That ought to be the method with the lowest capacitance possible because the contact points can be made very tiny, meaning their free space capacitance is miniscule.
Not really. I am dealing with MEMS right now. The main issue is that while stuff exists it only does so in the more scientific realm, and then when you start talking about >10k units/month sometimes you get a surprised look. The NRE costs to get that done are often incredibly high, pretty much like in the ASIC world.
-- Regards, Joerg http://www.analogconsultants.com/
But ... 0.45pF between the contacts. Problem with reeds is that the contacts but overlap quite a bit.
-- Regards, Joerg http://www.analogconsultants.com/
Check these out:
The ones with a guard screen could be bootstrapped and that'll take the coil out of the equeation, no matter how you drive it.
-- Regards, Joerg http://www.analogconsultants.com/
Phil Hobbs a écrit :
Phil,
your G6K 67dB isolation @ 10MHz translates to 0.14pF
Not bad but I once had similar a low capacitance need and used a panasonic RK1 which provides 60dB min isolation at... tada... 1GHz which translates to 3fF.
A completely different construction and wiring that I guess you can put to good work there.
Hmmm, too bad, I just see that it's been discontinued as of 08/2012. But they probably have a replacement, and digikey still have a few left.
How much max signal do you expect from your 1G output?
-- Thanks, Fred.
ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.