[Lowfer] MFJ-249 Antenna Analyser Mod.

[KD7JYK DM09]

I opened up my MFJ-249 antenna analyser today to get an idea of what it does 
and how.  I also found a pdf file of the manual and a relatively poor 
quality- but good enough, schematic.

It's pretty straight forward.  The oscillator is a free-running L/C network 
covering six bands, inductors ranging from a single turn of tinned wire to 
four slug tuned inductors of varying value.

Frequency readout is via a counter covering a few Hz (according to the 
manual) to about 200 MHz.  Band selection is by a six-position switch, the 
inductors are easy to see.  The tuneable inductors are easy to get to 
without taking the unit apart, just take the back cover off.

I didn't have a tuning tool so I didn't diddle the oscillator to see what it 
was capable of without modification.  I bought four diddle sticks today.

I didn't look too closely for placement of a switch for the inductor mod, 
but I'm thinking on top of the unit with the other controls fed with RG-174. 
I find the 249 fussy so I think it'd be wise to shield the leads.

While I'm at it...  Each time I use my analyser, I screw an Archer 5W dummy 
load to the top and sweep the band in question looking for a flat response 
before connecting to the device under test.  I'm thinking of adding a 
"Calibrate" switch with a precision non-inductive 50 Ohm resistor as well!

Thoughts?

Kurt