The most common name for this puppy is the "Amphenol microphone connector". The topic comes up frequently on the antique radios sites because it is used often on older service-grade test equipment such as VTVMs and signal generators. It was also the mic connector of choice for most ham radio transmitters of the era. Here's a blurb I wrote on the subject a couple of years ago that's got more than you want to know about the connector:<p>THE AMPHENOL MICROPHONE CONNECTOR<p>
There is a connector that was used quite a bit in the 1940s through the 1960s called the "Amphenol microphone connector." This connector was a screw-on type of coaxial connector popular for use on the high-impedance inputs of public address systems and for probe or output signal connections of service-grade test equipment such as VTVMs and signal generators. The test equipment built from kits (Knight Kit and EICO for example) especially used them. These connectors were also found as the microphone inputs for older amateur radio equipment.<p> The connector that is mounted on the equipment is a male thread and has a profile that's about 3/8" high and 5/8" in diameter. The threaded collar of the chassis-mounted connector connects directly to the chassis unless an insulated shoulder washer is used to isolate the mounting. The center conductor is an eyelet into which the signal line is soldered. <p> The cable end of the connector consists of a loose mounting collar that threads onto the chassis connector. This threaded portion of the connector connects to the shield of a shielded cable through a strain-relief spring and setscrew combination and the center conductor of the cable, the signal, solders to the center of the Amphenol connector, which like on the mating connector, is nothing more than a brass eyelet. When the cable end is threaded onto the chassis portion, the two solder blobs which are the center conductor connections, are pulled into contact.
The Amphenol microphone connector, supplied by Switchcraft has a 5/8-27 thread. You can find the data at
http://www.switchcraft.com/products/connectors-53b.html. I've seen the connectors sold through both Mouser Electronics and Kelvin Electronics.<p> There are folks who think, and will defend to the death, the notion that the "UHF" connector that is popular with amateur radio antenna systems and CB antenna inputs have the same mating thread. Although both connectors have a 5/8-inch major diameter, the these two connectors do not have the same thread pitch. It's a little harder to find official thread information on the UHF connector. You can find this information if you go to the Pasternack Enterprises site:
http://www.pasternack.com/main.htm Once there, click the "Smart Catalog" oval. Next, for "Product Category", select "CONNECTORS". Then for "Type", select "UHF FEMALE". For "Mount", select "4-HOLE PANEL". Then "bullet" the selection for "Non-Cable". Then click on the "View Part" oval. Now click on the "Large View" oval. Presto!! Finally, after all these steps, you see the UHF connector, threads marked "0.625-24" (5/8" = 0.625").<p> So, the Amphenol connector has a 5/8-27 thread and the UHF connector has a 5/8-24 thread. 10-24 (3/16-24) is a very common machine screw thread. You can lay the threads of a 10-24 screw in the threads of a female UHF connector, and they snuggle right in there perfectly. Lay that same screw in the threads of a male Amphenol microphone connector and you'll see that it just isn't right. It may APPEAR to fit if you're dealing with the 2 or 3 threads of the female cable end of the connector. Those threads on that part of the connector serve no useful purpose other than to help retain the collar, just like the few threads on the end of the PL-259 UHF connector. And 2 or 3 threads isn't enough thread to verify close pitches. <p> The UHF connector WILL crossthread on an Amphenol connector. Those who say it won't are either using Asian imports for their connectors or are only mating three threads or less or both. Asian imports are often manufactured with sloppy thread tolerances. Believe me, the 24 tpi UHF connector will quickly crossthread and bind up against the 27 tpi Amphenol connector if both parts are accurately machined.
