Padma, Please allow me to clarify some information I've seen on the posts regarding the Molex SMA, 73251-1850. I also want to thank both Scott and Julian for their kind words about our connector's performance. These high performance SMA connectors are a pressure contact variation of our 27 GHz SMA field-replaceable connector. George Hubbard (retired) worked closely with Scott and the Molex SI group to develop a variant that was more forgiving during assembly to a PCB by creating a "stub" contact that protrudes just a few thousandths beyond the circular ground ring on the connector flange. The contact is captured inside the connector using some traditional methods combined with some proprietary processes to optimize performance. Tolerances, materials and impedance compensation in these high performance SMA connectors are more tightly controlled than our standard SMA offering that work to 18 GHz. We have expanded our offering, based on customer feedback to include the mounting screws for attaching the connector to a PCB; 73251-1851. We also offer a smaller flange geometry (10mm) for higher density SI boards; 73251-3480. These connectors are manufactured in our facility in Indianapolis, Indiana. We've seen significant acceptance of these connectors worldwide and increasing volumes. Pricing is much less than the $40.00 price point you have referenced. At 100 pieces, our price for 73251-1850 is $14.00 each and lead-time is 6 weeks. It's quite possible; however, that one of our distributors is quoting higher prices for smaller quantities. Thank you for your interest in our 73251-1850. I hope I've helped provide a better understanding of our pricing and offering. Regards, Roger Kauffman Marketing/Sales Manager - RF Products (317) 834-5600 ext. 219 roger.kauffman@xxxxxxxxx -----Original Message----- From: Julian Ferry [mailto:julian.ferry@xxxxxxxxxx] Sent: Thursday, May 28, 2009 2:51 PM To: Scott McMorrow / Teraspeed; padma gundala Cc: si-list@xxxxxxxxxxxxx Subject: [SI-LIST] Re: SMA Connectors Hello Padma, Scott is correct (as usual!), and I will provide some additional information. We actually use quite a few of those Molex connectors in our Final Inch test board kits and in other test applications, so we are very familiar with it. It is a unique connector that fills a useful niche. The Molex connector is optimized for use at higher frequencies than the Samtec part you mentioned. As such, it is most likely manufactured to tighter tolerances (although I am not privy to Molex's manufacturing methods and tolerance limits). That will certainly drive up the cost. It also uses some more costly materials. And as Scott mentioned, the Molex part is a semi-custom design, which drives up cost as well. I expect the volumes Molex sells are fairly low too. So there are quite a few reasons it would cost more. As background, the original Molex design consisted of a longer pin and socket arrangement for connection to the PCB. A socket (or pin, I forget which) was soldered into the PCB. The center conductor of the connector would mate into that terminal. So in effect, the top assembly with the SMA interface was replaceable, with the soldered pin remaining permanently in the PCB. The semi-custom design basically trims the connector center conductor at the top of the PCB, and eliminates the soldered socket. This turns the center conductor / PCB connection into a compression type interface. This approach offers some significant SI advantages, and allows the total connector/launch bandwidth (based on return loss) to be pushed higher in frequency. Thru hole center conductor connectors generally perform less well than surface mount types, and this is almost entirely due to effects which occur in the PCB. Most of us are familiar with the negative effects of pin and via stubs. These issues can be minimized with stopped or back drilled vias, which are much easier to implement with surface mount parts. In addition, the surface mount or compression type interface also gives us the ability to use a smaller diameter via down to lower signal layers which allows more leeway in tuning the impedance of the launch. The Samtec connector you mentioned is very similar to the original Molex design, in that it requires a pin that is permanently soldered into the pcb. With out back drilling, it is possible to push the performance of that connector/launch combo to around 7-8 GHz or so. With the Molex parts, we can get launch/connector designs that function well to 20 GHz. Again, these numbers assume return loss or VSWR is the primary issue, as is often the case in SI measurements. If your primary design concern is another parameter such as insertion loss or isolation, then both connectors can be used to higher frequencies. One downside to the "quick and dirty" compression pin design is that it is less reliable than a soldered joint. It is more susceptible to intermittent connections and corrosion over time. This is usually not an issue in an SI lab environment, where an engineer is sitting in front of an instrument and can observe the quality of the connection in real time, and tweak it as necessary. The connector / PCB interface also tends to "wear out" with repeated applications and removal from test boards. The center conductor can push up into the connector body, which can lead to intermittent connections. And we have learned that you should not subject these connectors to severe temperature cycling when mounted on a PCB. But again, in a typical SI test lab environment, we find these downsides to be perfectly acceptable trade offs for the increased bandwidth. We have experimented with some compression type designs of our own. We were able to easily improve the performance in the launch area. But without tightening up the tolerances and changing some materials in other areas of the connector, we didn't get as much bang for the buck when the entire launch/connector area was considered. We might continue development work on an improved version that will hopefully address the reliability issues, while still offering the bandwidth improvements. But such a design will no doubt end up costing more, and we're still a bit uncertain about the overall demand for such a product. So in the mean time, if your application requires excellent return loss performance to 20 GHz or so, and you can live with potential intermittencies, then the Molex connector is a good choice. If you require better long term reliability, and/or lower cost, and if return los performance above 8-10 GHz is not a concern, then the Samtec connector is certainly worth considering. I hope you find this information useful. Julian Ferry High Speed Engineering Manager Samtec, Inc. -----Original Message----- From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On Behalf Of Scott McMorrow Sent: Wednesday, May 27, 2009 6:08 PM To: padma gundala Cc: si-list@xxxxxxxxxxxxx Subject: [SI-LIST] Re: SMA Connectors Padma The Molex connector was one that I had George Hubbard design for me back in 2004, when he worked at Molex. It takes a precision flange mount design and incorporates a built in beryllium copper pin that forms a signal contact with pad on a PCB. It was designed specifically to be a low return loss connector for precision measurements. The Samtec flange mount connector is designed to be a low cost connector, similar to other standard SMA flange mount connectors in the industry. The Samtec boys in Harrisburg can give you any information about it that you desire. Depending on your application, it may meet your needs. regards, Scott padma gundala wrote: > Hi, > > Anyone know the technical reason why one costs $40 and the other $3.75 > > Molex SMA Jack/connector :P/N 73251-1850 $40 > and > Samtec SMA Jack :P/N SMA-J-P-H-ST-PN4 $4 > Both are 50ohms, Samtec rates 12.5 GHZ. > > Any inputs from people who have experience using any of the above > is appreciated. > > Thanks a lot. > > Padma > > > ------------------------------------------------------------------ > To unsubscribe from si-list: > si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field > > or to administer your membership from a web page, go to: > //www.freelists.org/webpage/si-list > > For help: > si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field > > > List technical documents are available at: > http://www.si-list.net > > List archives are viewable at: > //www.freelists.org/archives/si-list > or at our remote archives: > http://groups.yahoo.com/group/si-list/messages > Old (prior to June 6, 2001) list archives are viewable at: > http://www.qsl.net/wb6tpu > > > -- Scott McMorrow Teraspeed Consulting Group LLC 121 North River Drive Narragansett, RI 02882 (401) 284-1827 Business (401) 284-1840 Fax http://www.teraspeed.com Teraspeed(r) is the registered service mark of Teraspeed Consulting Group LLC ------------------------------------------------------------------ To unsubscribe from si-list: si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: //www.freelists.org/webpage/si-list For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List technical documents are available at: http://www.si-list.net List archives are viewable at: //www.freelists.org/archives/si-list or at our remote archives: http://groups.yahoo.com/group/si-list/messages Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu ------------------------------------------------------------------ To unsubscribe from si-list: si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: //www.freelists.org/webpage/si-list For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List technical documents are available at: http://www.si-list.net List archives are viewable at: //www.freelists.org/archives/si-list or at our remote archives: http://groups.yahoo.com/group/si-list/messages Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu -------------------------------------------------------------------------- CONFIDENTIALITY NOTICE: This message (including any attachments) may contain Molex confidential information, protected by law. 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