Quantum Coax
Frequently Asked
Questions
FAQs Filter
Coaxial Cable | Connectors | Cable Assemblies | Applications | Ordering & Quotes | About Quantum Coax
Coaxial Cable
How are the MicroFlex cables designed for cryogenic use?
MicroFlex coax cables use materials that minimize thermal heat transfer to the cold plate of a cryostat while minimizing electrical loss at the same time. We also use dielectric material that is low outgassing for the vacuum environment of cryostats.
Are the MicroFlex cables formable or fully flexible?
MicroFlex coax cables are fully flexible, not formable like other coax cables. It remains flexible even at low temperatures which makes it suitable for applications that use nanopositioners.
Is stainless steel MicroFlex magnetic?
Yes, our stainless steel MicroFlex coax cable is slightly ferromagnetic.
Are phosphor bronze and niobium-titanium MicroFlex cables non-magnetic?
Yes, both are non-magnetic.
What is the characteristic impedance of MicroFlex coaxial cable?
All cables are designed to have 50Ω characteristic impedances.
What is the maximum voltage that can be used with the MicroFlex coax cable?
The maximum voltage that can be used with MicroFlex coax cable is about 1kV.
What is the maximum current that can be used with the MicroFlex coax cable?
We recommend using 200mA or less for our MicroFlex cable. Due to the higher resistance of MicroFlex cable materials such as stainless steel, higher currents will cause the center conductor to heat up and potentially cause damage to the dielectric while also creating excessive heat that will transmit to the cold plate of a cryostat.
What is the minimum bend radius of the MicroFlex coax cable?
The minimum bend radius of MicroFlex cable is around 0.200 in. (5 mm).
Why does the coax cable not have outer insulation?
We intentionally don’t add outer insulation to our MicroFlex coax cable to minimize outgassing and also to make the cable easier to thermally lag at temperature stages of a cryostat.
Do you offer custom cable designs?
Yes, we can make cables with custom materials and sizes similar to our MicroFlex coax cable. There is usually a minimum order quantity (MOQ) required for this and certain design constraints. Please contact us if you are interested in this.
Connectors
What frequency can I use with different connectors?
Consult our Connectors page to learn more about the frequencies that different connectors are rated for.
Do you offer non-magnetic connectors?
Yes, we have non-magnetic options for many of the connector types that we offer.
Are SMP and GPO connectors the same type?
Yes, they are the same type and can be used interchangeably.
Are SMPM, GPPO, and Mini-SMP connectors similar?
Yes, they are the same type and can be used interchangeably.
Are SMPS and GP3O connectors the same?
Yes, they are the same type and can be used interchangeably.
Are 2.92mm and K connectors the same type?
Yes, they are the same type and can be used interchangeably.
What does “smooth bore” limited detent” and “full detent” mean?
These terms are used to describe the force required for engagement and disengagement of mating push-to-connect connectors such as SMP and SMPM. The detent level is controlled by the geometry of the male (pin) connector. Smooth Bore (SB) connectors require the lowest disengagement force at around 0.5 lbf., while Limited Detent (LD) requires 2.0 lbf, and Full Detent (FD) requires 5.0 lbf for disengagement. We recommend limited or full detent style connectors for cryogenic use.
What type of attachment method do you use for connectors?
We strictly use connectors with soldered connections. Soldered connections maintain a consistent connection over repeated thermal cycling and have lower loss at cryogenic temperatures.
Cable Assemblies
What connector options do you offer?
Review our connector page for a list of the connectors we offer. Please contact us if you do not see the connector you need.
What customization options are available?
We can customize the cable length and connector configurations. We can also add a non-conductive outer jacket to the cable assemblies if desired.
Is there a minimum cable length you can fabricate?
We can fabricate almost any length for any cable type except niobium-titanium. The minimum cable length for the niobium-titanium cable is about 2 inches.
Can you fabricate cables with different solder compositions?
Yes, we normally use Sn96Ag4 solder which is good for vacuum and also relatively soft, but we can also use other solder compositions such as Sn63Pb37 and Sn96.5Ag3.0Cu0.5 on request.
Can you fabricate cable assemblies with connectors that are not listed on the website?
Yes, we can fabricate cable assemblies with other connector types not listed on the website. Contact us for more information.
Are the cables ready for use in vacuum when I receive them?
Yes, we thoroughly clean and dry each cable so that it is ready for vacuum once you receive them.
What testing is standardly done on cable assemblies?
We standardly conduct continuity and high resistance short testing for the center and outer conductor of each cable assembly.
Can I request more involved testing such as S-parameter, TDR, Hi-Pot, or other tests?
Yes, we can do S-parameter, TDR, Hi-Pot and resistance testing for an additional fee.
Do you test completed cable assemblies at low temperatures?
We have in-house cryostat testing capabilities, but we currently don’t offer this testing for standard orders except for special circumstances.
Applications
What is the operating temperature range for cable assemblies?
Our cables are designed to be operated from 10mK dilution refrigerator temperatures up to 400K bakeout temperatures.
Can the NbTi cable assemblies be used in a DC or AC magnetic field?
Yes, but with restrictions. High magnetic fields coupled with current flowing through the cable can cause the NbTi cable to cease its superconducting state.
Can the NbTi cable assemblies handle very high currents?
No, niobium-titanium wire can handle large amounts of electrical current when superconducting but the connector bodies of the cable assembly will likely heat up under high current which will heat the adjacent niobium-titanium cable and pop it out of its superconducting state. We do not recommend using high currents.
Are the flexible NbTi cable assemblies completely zero resistance when superconducting?
No, our NbTi MicroFlex cable has zero resistance when superconducting, but the connector bodies and interconnections have a very small amount of electrical resistance.
What temperature does the NbTi MicroFlex coax cable superconduct?
The NbTi MicroFlex cable superconducts below 9K and the solder connections superconduct below 3.7K.
Will the NbTi cable assemblies superconduct if I am using a 3K cryostat with a 30K radiation shield?
We normally don’t recommend this unless proper thermal lagging and a 4K radiation shield are used. It is difficult to consistently get the NbTi MicroFlex coax cable to reliably superconduct with a 3K cryostat that has a 30K radiation shield.
Can MicroFlex cable assemblies be used for applications that use nanopositioners?
Yes, the flexibility of our MicroFlex coax cable makes it ideal for applications with nanopositioners.
What is the best way to thermally lag the cables?
We recommend a gentle thermal “clamp” or winding the cable around a thermalizing bobbin with a generous diameter. The thermalizing length is critical to getting the center conductor of the MicroFlex coax cable to properly thermalize. We recommend a thermalizing length of at least 1-2 inches.
Can the cables withstand a bakeout for UHV?
Yes, our cable assemblies can handle bakeout temperatures up to 400K.
Ordering & Quotes
Do you have standard cable assemblies available, or is everything custom?
We do not have standard length “off-the-shelf” cable assemblies. Each cable assembly is custom built to each order.
Can I order multiple cable lengths or configurations in the same order?
Yes, we realize the need for having multiple cable lengths and configurations for different applications and will build whatever configurations you need.
Do you have a minimum order quantity?
NO!
Do you offer volume discounts?
Yes, for higher quantity orders we do offer volume discounts.
What information do I need to provide to get a quote?
Quantity, cable material, cable length, connector types and genders for each end and a shipping address.
What is the standard lead time?
Our standard lead time is 3-4 weeks.
How are orders processed?
We process orders on a first-come, first-serve basis.
Can you ship internationally?
Yes, we can ship internationally.
About Quantum Coax
Where is Quantum Coax located?
Bozeman, Montana USA
Does Quantum Coax manufacture everything in the USA?
We manufacture the cable and cable assemblies in-house using connectors purchased from a variety of manufacturers.
What industries does Quantum Coax support?
Quantum Coax is dedicated to supporting cryogenic and quantum industry.