GigaFlight, M39029 Size 8 Coaxial Socket Contact, 75 Ohm With Seal

GIGAFLIGHT’s selection of avionics connectors includes 75Ω size 8 pin and socket contacts suitable for MIL-DTL-38999 series I, III & IV applications. Our size 8 coax contacts are compatible with 75Ω coaxial high-definition video cables. Designed to meet or exceed SAE-AS39029 requirements, these contacts are ideal for aerospace and defense applications involving high vibration, extreme temperatures and other harsh environmental conditions.

Designers beware: Some manufacturers list size 8 coax contacts as 75Ω because the backend of the contact accommodates a 75Ω cable. However, the impedance of the mated pair could be 50Ω. Not paying attention to this risks signal degradation or damage to the contacts (more information below).

75 Ohm M39029 Size 8 Socket

P/N: GF7-8S303HD

Compatible cables: GF7-303D, GF7-TX303D, V75268, V73263, V76261, L7626TX

Mates with: GF7-8P303HD, 190740-01, 190940-01, 190740, 190940

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Know Your Contact Interface Impedance

When specifying 75Ω size 8 coax contacts, don’t overlook important details in the fine print. Size 8 coax contacts are often listed as 75Ω contacts because they’re paired with a 75Ω cable. Upon closer inspection you’ll find the interface impedance of the mated pair to be either 50Ω or 75Ω.

How did this happen?

Size 8 coax contacts listed as 75Ω but with a 50Ω interface can be considered hybrids. Back when analogue video applications were the standard, common practice was to use these hybrid contacts as there was no signal degradation. With low frequency analogue video applications, the change in impedance in the interface didn’t affect signal quality or create SWR (standing wave ratio) complications. It was easy to create a contact with a 75Ω cable receptacle and leave the interface the same.

What’s changed:

Today, high-bitrate digital video content has difficulty passing through a hybrid contact. This is because digital signals are degraded by the change in impedance through the interface (75Ω cable to 50Ω interface). As a solution, GIGAFLIGHT has developed a true size 8 coax contact which has a 75 ohm cable entry and a 75 ohm mated interface.

Be mindful that the outer form-factor of both true and hybrid contacts are the same, meaning they all fit within a standard connector insert. However, a hybrid contact will not mate with a true contact and the user may experience intermittent failures or damage to the center contacts when attempting to mate the pair.

True 75 Ohm Size 8 Coax Pin/Socket Contacts in Stock & Ready to Ship

GIGAFLIGHT has solutions, offering true 75 ohm M39029 size 8 pin and size 8 socket contacts that are compatible with PIC’s 190740-01 and 190741-01. The materials, physical/electrical characteristics and standard tooling are all the same. If you want to minimize your risk of long lead times, we recommend adding GF7-8P303HD and GF7-8S303HD to your BOM as an alternative to these other connectors.

For more information, see our 75 ohm coax contact cross-reference page.