TNC

According to Amphenol the (TNC) Threaded Neill-Concelman connector was invented in the 1950’s and were named after Paul Neill of Bell Labs (now AT&T or Lucent depending on your point of view) and Carl Concelman of Amphenol. The TNC over time has become a higher frequency connector. The TNC connector has four flavors: Standard 50 Ohm, Reverse Polarity 50 Ohm, High Frequency 50 Ohm, and Standard 75 Ohm. The Standard 50 Ohm connector goes from DC to a top frequency of 6-11 GHz depending on the manufacturer. The High Frequency TNC will go to 18 GHz. The 75 Ohm TNC and the Reverse Polarity will go from DC to 1-2 GHz, depending on the Manufacturer. The better TNC's do better than -60 dB in RF leakage at 3 GHz.  Other factors will be the cable that is connected to the connector.

Why does the reverse polarity exist?

There are occasions where the supplier wants to make sure the customer plugs into correct jack. Reverse polarity solves this problem. Changing the polarity is not for free. The cost is frequency response. Most manufacturers simply change the pin sex. So a pin that was designed for a male is substituted for a female. Since the pin was not designed for that connector it tends to degrade it over frequency. 

Little know fact:

The internal workings of the TNC and the BNC are very similar. The major difference is the TNC is threaded and the BNC is a Bantam. Which is the reason for their name -Connector trivia.

BNC Connector:

According to Amphenol the (BNC) Bantam Neill-Concelman connector was invented in the 1940’s. This connector has many advantages: easy to disconnect and connect. You know when the connector locks it snaps. Like the TNC, and N Type the BNC is hard to damage. The BNC comes in three flavors. Standard 50 Ohm, 75 Ohm and reverse polarity connector. You can get all three built to your custom length www.OnlineCables.com .

Why Should I use a BNC?:

It is a great snap-on connector. It goes on quickly you know when it locks and if your signal is DC to 4 GHz (1GHz Digital) the BNC works well.

When Should I not use a BNC?

Quick connect and disconnect with lower frequency is the most popular reason. The Standard TNC and N-Types will perform well from DC to 11GHz with high frequency models going to 18GHz. The BNC’s are usually limited to DC to 4 GHz.  Another issue is the BNC can snap off just as easy as it snaps on. If you are in a high vibration environment the BNC may not be suitable. To solve this problem a few military BNC versions have guide wire holes to tie down the connectors. High power and high EMI can cause the BNC to leak RF either into the cable or radiate outward. The good ones will be –55 dB to 3GHz the lesser ones can be as low as –25 dB and even lower if a poorly shielded cable is attached.

N-type Connector

According to Amphenol the N-type is the Neill-Concelman connector invented in the 1950’s. The N-type is a large version of the TNC. The N Males are about 0.825 inches (20.1 mm) outside dimension vs. 0.630 inches  (16 mm) for the TNC. The N-type is a thread on connector with a long neck. This provides excellent EMI protection. In many cases > –90 dB  for RF leakage which is dependent on the manufacturer and cable type.  The N-type comes in 4 flavors. The standard 50 Ohm, the 75 ohm, the reverse polarity and the 18 GHz version.

When Should I use a N-Type?

The N-type is a good choice for an external mount connector that needs to withstand abuse. Size goes both ways. With a larger connector you get the toughness of the more material. Most manufacturers use brass as the base metal of the N type. Stainless Steel N-types are available, but can be expensive (stainless steel typically has an 88,000 psi tensile strength). If you need a big tough connector the N-type is your friend. If size is crimping your style look toward the TNC or the SMA.  The frequency response for the N-Type is very similar to the TNC. Most basic models go to 11 GHz and most high frequency versions go to 18 GHz. The N Type is better in higher voltage 500 vrms for the BNC vs 2500 vrms at 50Hz for most N types. The N-Type is better for EMI 90 dB vs 60 dB.

When should I not use N-Type?

Small cables do not do well with N-types. Example 0.047 (1.20 mm) Simi rigid RG-178 (0.078 OD (2 mm) ). Basically big connector on small cable is a poor choice. 

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