Batboard

Just curious what type of coax is the best for mobile installations. I know everything comes with RG-58, but is there better? I would imagine something like LMR400 would somewhat difficult to work with on a smaller vehicle.

Cable losses are stated in decibels per 100' at specific frequencies. And losses vary greatly with frequency

For base stations with long cable runs, you should always be buying the very best, lowest loss cable (that fits the application) you can afford. There are other factors to consider like higest rf power used, weather resistance, cable radii, and whether the cable will be buried or not..

Mobile installs, with their relatively short cable runs, can utilize a higher loss cable... Again, you need to balance the actual loss based on frequency and cable run length against installation ease and durability. Some of the hardline type stuff works great for base use if you can secure it well to the building and tower. However, much of this stuff will not take being flexed much. Almost anything in a vehicle is subject to movement between body sections AND a lot of vibration - almost mandating multi-strand flexible center conductors. Also, trunk lid mounts do present at least one area where the cable will be flexing fairly often.

Just avoid the temptation to use something like RG-174 -- It is easy to install - being about the diameter of #14 insualted wire. However, it's not durable, and is generally very lossy even over short runs.

The quality is more important than the type... I have seen the center conductor migrate (melt) and touch the shield from just running past the heater duct. I have also replaced some cheap RG58 with some good RG-223 on a celllphone setup that was like night and day......

Times Wire makes a LMR240 cable that is the same physical size, 1/4 in. dia, as RG8X and having much better specs then RG8X.
LMR240 Ultra Flex has a stranded center conductor for applications requiring flexing, ie; a trunk lid mount. Both have a %100 shield foil AND braid. RG8X connectors work, or PL259 with the RG59 type reducer.

And, if you must have RG58 sized cable, Time Microwave also makes LMR195, works with the crimp-on Mini UHF connectors.
Stan

On runs over 20' I've used and highly recommend Times Microwave's LMR200 cable. However, for most car/truck runs that average around 8'-10', RG-58 is just fine. The loss is only a concern when running anything over 25'-30'.

...and for anyone just starting out, the following may be helpful:

1. To use RG58 with a standard PL259 connector, the screw-in reducer is called a UG-175.

2. To use RG8X with a standard PL259 connctor, the screw-in reducer is called a UG-176.

3. RG8X is the same size as the 75-ohm cable which is called RG59. The cable is intended for TV use, but the reducer used is the UG-176 if you're using a PL259 connector.

4. Most of the theory for this subject can be found in the ARRL Antenna Book, including diagrams showing how to solder the cable to the connector.

Tom, W2NJS
...in D.C.

Ever melted the cable while trying to solder the shield and insert of a PL259, or found that the solder never made it into the shield and left you with a crappy ground on the connector?
Then try soldering the shield to the insert... only.
Just lay the shield back over the barrel of the insert, tie it in place with a few strands of the shield wire... making sure that it's laying evenly and smoothly on the sleeve.
Solder the shield to the insert, let cool and trim off the excess shield wire. Then screw the assembly into the connector body... use pliers to make it tight, then solder the center conductor, only.
It will not come apart as I have seen with many "less than perfectly" soldered connectors... and the insulation never gets the chance to flow and short inside the connector.
Also, if you ever need to salvage the connector, "it's a piece of cake" to take apart.
Stan