How would you tell what frequency a mobile whip is designed for?

[WB4KFO]

Hello all.  I have several mobile antennas bought at flea markets and thrift stores and I don't know what frequency they work for.  One is a classic old Antenna Specialists mobile whip with a long grey base and a magnet mount that has a thrift store price but no markings.  It could be CB or 152-174 mhz.  Thanks for any help.

[K3MRI]

Hey Bill, antenna analyzer!! Bring the antennas to the next K4US meeting and I'll bring my analyzer. Just try to remind me beforehand.

[WB4KFO]

Thanks Jim.  I don't go to club meetings.  Would the breakfast at Primo's be ok?

 

[K3MRI]

36 minutes ago, WB4KFO said:

Thanks Jim.  I don't go to club meetings.  Would the breakfast at Primo's be ok?

Ooops, that's what I meant, breakfast 🙄 Duh. Yes, I'll bring my analyzer and adapters in case you have different connectors. Now, here's hoping I don't forget!!!

[N3IXY]

A 5/8 wave 2m whip will look similar in length to a 11m mobile whip, though the 11m whip will have a loading coil in the base. The coil may be visible if the base can be disassembled a bit.

Do you have a SWR meter? That would provide some indication as to where the antenna is resonant.

Also, you can also do some brief A/B testing between a known resonant antenna and the unknown, and see how well your signal propagates. (Receive characteristics won't necessarily be sufficiently different to form a judgement of an unknown.) 

[WB4KFO]

On 11/8/2019 at 10:47 AM, N3IXY said:

 

Thanks Peter.  That was very helpful.  The antenna specialists usually provided a coil hidden in the base.  If I remember correctly, it was not hard to pry it off unless it was glued to prevent moisture.