SSJ_Micro_Coax_Cables.docx

JUSTIFICATION FOR SOLE SOURCE (Simplified Acquisitions <$150K)

The service or material listed on N6228518RC074AE is sole source and competition is precluded for reasons indicated below. There are no substitutes available for this material or service.

Restricted to the following source. Provide original manufacturer’s name. (If a sole source manufacturer distributes via dealers, ALSO provide dealer information.)

Brand Name: Manufacturer: Micro-Coax, Inc

CAGE: 64639

Manufacturer POC: Sherry Ann Petrakis Phone nr. 800-223-2629 Email:

Mfr. Address:

206 Jones Blvd.

Pottstown, PA 19464

Authorized Resellers:

__X__ Description of the item or service required, the estimated cost, and required delivery date.

The U.S. Naval Observatory (USNO) Washington, DC requires replacement cables for its clocks. A total of 288 cables are required. Under Joint Chiefs of Staff instruction CJCSI 6130.01F, the U.S. Naval Observatory (USNO) is directed to not only supply the Master Clock (MC) for the DOD at a level that meets or exceeds mission requirements but to conduct relevant research to help ensure continued US military superiority through advanced technology. Critical to USNO Time Service Mission is providing the best possible Master Clock to fulfill the mission requirements of GPS and other programs at the nanosecond and sub-nanosecond level. Time Services must maintain these systems and do so using the most stable and lowest noise hardware. The current request is to procure replacement cables that will deliver clock signals consistently over time and temperature.

__X__ Specific characteristics of the material or service that limit the availability to a sole source (unique features, function of the item, etc.). Describe in detail why only this suggested source can furnish the requirements to the exclusion of other sources.

The USNO Time Services did extensive market research: In order to find the best cable or cables, a large number of cable manufacturers were reviewed to see who could provide the very best phase stable cables. It is very important that the cable properties don’t change over temperature because this will change the timing of the clock signals.

Some of the cables reviewed:

Micro-Coax UFA147A 0.147” Diameter Max Freq: 40 GHz This RF/Microwave cable was very well constructed with nice long SMAmale connectors with a double boot for strain relief. The loss and phase stability was measured to be very good. An additional test was run by looking at the phase delay with a vector network analyzer while wrapping and un-wrapping the cable around the calibration torque wrench. This cable changed the least amount for the cables tested when twisted and untwisted. A 6-foot cable costs about $362 with SMAmale to SMAmale connectors attached and double booted.

Micro-Coax UFB197C 0.197” Diameter Max Freq: 26.5 GHz This RF/Microwave cable is very well constructed with nice long SMAmale connectors with a double boot for strain relief. This cable is bigger than its counterpart UFA147A. The loss and phase stability was measured to be very good. An additional test was run by looking at the phase delay with a vector network analyzer while wrapping and un-wrapping the cable around the calibration torque wrench. This cable changed about the same as the TMS PT402 cable when twisted and untwisted. A 6-foot cable costs about $435 with SMAmale to SMAmale connectors attached and double booted.

Andrews FSJ1-50A 0.250” Diameter Max Freq: 20.4 GHz This RF/Microwave cable was very well constructed. The cable itself feels like an armored cable, however it is a helix construction around a foam core. This cable must be worked with carefully so as to not crush the tube and change the characteristics of the cable. The velocity of propagation was the highest of all the cables tested. The loss was very low, but the maximum frequency is lower than most. A 6-foot cable costs about $50 with SMAmale to SMAmale connectors attached. This cable is very hard to work with and is not well suited for tight corners and repeated mate and de-mate applications. It is also very large in diameter so the density of cables per small area is much smaller.

TimesMicrowave SiO2 0.141” Diameter Max Freq: 38 GHz This RF/Microwave cable is touted to be very phase stable and it was pretty good. It is a semi-rigid cable with a stainless steel outer jacket. The dielectric is a low density, high purity, silicon dioxide. Since this is a semi-rigid cable it is not suited for long runs or many bends. This type of cable is good for permanent installations where one bends up the cable and then leaves it. A 6-foot cable costs about $295 with SMAmale to SMAmale connectors attached.

TMS LMR100A 0.110” Diameter Max Freq: 9 GHz This RF cable was designed for the telecom industry. It is called Land Mobile Radio cable. It is a drop in replacement for RG-174. This particular cable was very cheap and not constructed very well. The boot on the connector was initially glued to the connector and we found that a signal had more than 30 dB of loss at 5 MHz for the 20-foot length that was provided. This is just not a high quality cable and the sample provided was DOA. A 6-foot cable is $52 however the quality doesn’t warrant a purchase order at any price.

TMS LMR200 0.195” Diameter Max Freq: 9 GHz This RF cable was better in construction than the LMR100A, but it still did not have a very good connector/boot construction because the vendor got glue on the connectors. This is also a Land Mobile Radio cable. Discussions with Matthew Long revealed that the LMR cables are very sensitive to pressure changes. The dielectric is almost like a jello type material that is easily distorted and changed due to pressure and flexure. We chose to not test either of the LMR cables due to Matthew’s report. TMS also reported that they recommended the Phase Track over the LMR cable. A 6-foot section of this cable is about $52 with SMAmale to SMAmale connectors attached. Although this was a less expensive cable, the construction, sensitivity to pressure changes, and lower isolation severely reduces its overall value.

TMS PT402 0.160” Diameter Max Freq: 18 GHz This RF/Microwave cable was Times Microwave’s best offer for a phase stable cable. This is called PhaseTrack-402. This was a pretty nice cable. The construction and connector quality still did not measure up to that of the two samples from Micro-Coax. TMS seems to struggle with getting the glue and boot on their connectors without getting glue on the body of the connector’s nut. A 6-foot cable is about $180 with SMAmale to SMAmale connectors attached.

GORE Cable Matthew had a variety of cables that we looked at in addition to the samples that we brought. We chose a bench top type Gore cable that looked like it warranted testing. This cable was well constructed, fairly durable, and performed quite well.

Testing performed:

The Micro-Coax UFA147A, Micro-Coax UFB197C, Andrews FSJ1-50A, TMS SiO2, TMS PT402, and a Gore cable were tested using a vector network analyzer in a Tenney thermal chamber.

Matthew Long at NRL generously provided the facilities and time to work through the tests. A vector network analyzer was connected to a pair of coaxial microwave switches that in turn fed pairs of very high quality cables into a Tenney Chamber. Each path was calibrated independently just inside the chamber. The “device under test” cables were connected to the reference cables just inside the chamber interface so as to reduce their contribution. The chamber was set to 13.5C and soaked for 1 hour. At each frequency the coaxial switches were stepped through, the appropriate calibration table was loaded, and the results printed.

The USNO measured the phase at various temperatures from 13.5C to 33C using a span from 95 MHz to 105 MHz with markers at 99, 100, and 101 MHz. The phase at each of the three marker frequencies, for each temperature was averaged together. This helps to capture some of the variation and slope at each temperature point. The absolute phase then had to be subtracted out and changed to a delay in seconds. Now this is the delay through the cable tested. This has to be normalized according to its length and then multiplied by the length of cable desired to see how the phase change would affect the particular length of cable desired. This is a little funny when cables go through different rooms or chambers as different sections will be at different absolute temperatures.

Summary:

After reviewing the various cables and testing them over temperature and with some twisting stress, only the Micro-Coax produced a very phase stable cable that was also flexible and suitable for the environment that the USNO is operating in. The USNO needs these cables to replace existing cables and to meet the demanding requirements of the Master Clock.

_X_ The requested material or service represents the minimum requirements of the government.

The USNO Time Sensitive Mission is providing the best possible Master Clock to fulfill the mission requirements of GPS and other programs at the nanosecond and sub-nanosecond level. Times Services must maintain these systems and do so using the most stable and lowest noise hardware. This order is to procure extremely high performance replacement cables that will deliver clocks signals consistently over time and temperature. A number of different vendors were researched and extensive testing took place to determine that Micro-Coax produced the type of cable needed for stability, flexibility, suitability and durability under the temperatures and stress required.

CHECK & FILL IN ALL APPLICABLE BLANKS BELOW

_X__ The material/service must be compatible in all aspects (form, fit and function) with existing systems presently installed/performing. Describe the equipment/function you have now and how the new item/service must coordinate, connect, or interface with the existing system.

Reviews of various cables from numerous companies were tested to determine if the form, fit, and function were compatible with the current system. The test determined that over temperature and with some twisting stress, only the Micro-Coax cables produced a very phase stable cables that was also flexible and suitable for the environment operated in. The cables replace the existing cables and meet the demanding requirements of the Master Clock.

____ A patent, copyright or proprietary data limits competition. The proprietary data is

__X__ These are “direct replacements” parts/components for existing equipment.

__X__ Other information to support a sole source buy:

Micro-Coax is the original equipment manufacturer (OEM) of the required cables. There exist resellers of the required cables.