Coaxial Cables

Design Notes

1. The loss of all coaxial cables & filters between the antenna and the radio should not exceed 2 dB. Refer to following attenuation charts:
   • Coax Attenuation Charts
2. Lengths of coaxial cable should be kept as short as practical to minimize attenuation.

Use Cases

Cable Type	Usage
LMR-400	Used for primary run from antenna to lightning arrestor (if used).
LMR-400-UF	Used from lightning arrestor (if used) to the radio, or filter(s) preceding the radio. ‘UF’ (Ultra-Flex) variation of LMR-400 is often easier to route inside a dwelling.
RG400	Used to connect filters, preamplifiers, & other hardware to the radio.
RG316	May be used in place of RG400 where increased flexibility is needed; cable length(s) must not exceed 12″ due to loss characteristics.
RG8X or LMR-195	May be used for short runs of 25′ or less. However, LMR-400 variants should be used when practicable.

Brands

1. Primary runs of LMR-400 variant coaxial cable should be authentic Times Microwave cable when practical.
   • Acceptable LMR-400 alternatives include:
     • CommScope CNT-400
     • Shireen RFC-400
     • DX Engineering 400MAX
   • Any brand not listed above should be avoided.
2. Coaxial cable should be purchased from a trusted source known to deliver quality, authentic products. Our preferred sources include (in order):
   • wifi_expert eBay Store
   • The Antenna Farm
   • DX Engineering

Connectors

1. N connectors should be used when practical, especially outdoors. Unlike most connectors, N connectors are designed to prevent water ingress.
2. When installing connectors yourself or specifying connector brands for a custom length of coaxial cable, the following brands are preferred (in order):
   • Times Microwave
   • Amphenol
   • Pan Pacific
   • RFI
   • Any brand not listed above should be avoided.

Jumpers

1. The correct connectors should be applied to each length of coaxial cable to avoid the need for jumpers or adapters. Each additional connector or adapter increases signal loss.
   • Exception: A jumper from a stiff cable like LMR-400 to the radio is encouraged to reduce stresses on the radio’s connector.
2. When jumpers are used, they should be no more than 12″ in length.
3. Jumpers should be used in lieu of adapters.

Damage

1. Care must be taken not to damage, crush, or kink coaxial cable. Do not route coaxial cable through windows, doors, or other areas where it could be damaged.
2. Lengths of coaxial cable with visible or suspected damage should be scrutinized and replaced if necessary.
   • A damaged coaxial cable may still receive signals, but will suffer from additional attenuation.
   • Do not assume that a length of coaxial cable is good due to receiving a nearby strong signal.
   • Damage may not always be visible. The center conductor and shielding are often damaged from crushes or kinks without visible exterior damage to the jacket.
   • Use an antenna analyzer or VNA to test a suspect of coaxial cable that is suspected to be damaged.