Hello to all, I am a owner of a MFJ-259B and I would like to use it to test my home made antennas, and my question is regarding the resonant I have found this info from a known manufacturer and attached 2 images for your appreciation... Basically I would like to know if you have tried to measure the ressonant frequency of a trap using this method and your MFJ-2*9. I know that MFJ sells an accessory to make our MFJ a dip meter, but if this method works I will be very happy and I will not need to buy it. The more technical question - and the most important - is why does the trap ressonates at that particular frequency without the "rest" of the antenna, ie telescopic whip or the wires after and before the trap. I've read the user manual but it doesn't explain why, just how, and googling made me lost. I also attached a print screen of a youtube video where a new antenna analyzer is used to do it the same way. Thanks in advanced, Luis, CT2FZI TRAP FREQUENCY MEASUREMENT (It also acts like a "grid-dip" meter, but easier to read, and with digital frequency readout !) Bonus:Not in all Analyst Instructions. A simpler way to measure the resonant frequency of a trap, or any tuned circuit, is to connect a piece of wire between the Analyst output and the Analyst ground (the ground screw next to the coax connector, or the outside of the coax connector.) The wire can be a few inches to many feet long.(Note:You must disconnect the trap from any antenna to measure its resonant frequency.) Put the Analyst in the Z mode. You will read a small Z which simply represents the inductance of the wire. Now put the wire near the trap. As you tune the Analyst frequency, Z will increase dramatically at the trap resonant frequency! The frequency of peak Z is the trap resonant frequency. If the trap has high Q and is large you can probably see the jump in Z with the wire several inches from the coil. For a small coil, you might need to wrap the wire into a small loop at the end and bring it near the coil. No fancy plug-in coils are needed such as a grid-dip meter requires...just a few inches of wire! And the Analyst's digital frequency and Z readout pinpoint the resonant frequency exactly. The same wire can usually be used over the entire frequency range of the Analyst, so you can also forget about the many plug-in coils that a grid-dip meter requires.