Topband: MFJ-259 Antenna Analyzer

[Richard Detweiler]

Without the frequency display you won't know what frequency the SWR dip is on.
 
The earlier model of the 259 (not B, the one with the two buttons on top for input & gate ) did not really find the resonant frequency,  it did find the lowest SWR, but often this is not the reasonent frequency.
 
The earlier model used a opto electronics inc. UTC 150 frequency counter.  No replacments are available.  The counter chip may be but not sure of it.
 
A modern 259B can determine the reasonant frequcy by the R/X display on the main screen.  It's parts can be had at MFJ.
 
If the older unit frequency counter is out, you can try another unit to determine the frequency.
 
For the older unit, there is another counter module from N3ZI that may be used to put in or on the unit.  The RF tap will have to be routed out to it and then it will be functional.
Best WishesRichard K5SF