Used Comm Antenna

[BMC_Dave]

So I found myself a nice little comm antenna at the fly market, a Mooney-7002 that looked to be in great condition. Price was right as a desk ornament so if I can use it as an actual antenna I?d be quite pleased. The retro look is pretty slick in my opinion I have some questions about testing it with my also newly acquired MFJ-259C, which I?m waiting on a BNC adapter for.

If I get a SWR below 2 at the various test frequencies (118, 127, 135) does that guarantee I won?t fry my 430 when I hook it up?

Is it necessary to test the antenna as-installed to determine if it?s radio safe? Rather, can this be determined without needing a ground plane?

Throwing my ohmmeter on the 7002, I see the center conductor and BNC terminal are electrically connected. In fact the center conductor appears to also be connected to the mounting screw studs, is this normal? I checked my brand new ACK ELT antenna and these are isolated from each other, but I recall this can vary between antennas so I thought I?d ask.

Is there anything else I should test than the SWR? I?m just learning the basics of antenna theory and that seems like it?s the most useful.

[BobTurner]

You definitely need a ground plane.

[BMC_Dave]

Originally Posted by BobTurner

You definitely need a ground plane.

To determine the quality of the installed configuration, sure. But what about determining whether the antenna is safe to connect to a transceiver?

[Carl Froehlich]

Put the antenna on a mount, add two pieces of wire (any gauge) to the base screws, the wire pieces 24? long and about 180 degrees apart. Connect your MFJ antenna analyzer and find out how it is working.

Have the now antenna and temporary ground plane spaced a few feet from any large metal objects.

There is no magic about these dirt simple antennas. They are just a single conductor connected to the center pin of the BNC base connector (or screw terminal for the really old antennas).

Carl

[BMC_Dave]

Originally Posted by Carl Froehlich

Put the antenna on a mount, add two pieces of wire (any gauge) to the base screws, the wire pieces 24? long and about 180 degrees apart. Connect your MFJ antenna analyzer and find out how it is working.

Cool, so I can mock up a temporary ground plane to test the antenna. Thank you!

So does getting a good SWR on those frequencies guarantee I won't fry a radio? Is a ground plane necessary to determine if an antenna is safe? Does getting a tone between the conductor and connector/housing indicate I have a short, or is that just how some antennas are? Is there anything else I should look at than SWR?