Put the MFJ-208 back together and tested it out with the antennas for my handheld.
I think it works. The LED light comes on when I turn the power on. I can hear a tone and static on my radio at about the same frequency as what’s indicated by the dial. The SWR meter moves when I change the frequency selector dial.
I’m not sure I’d use it for actually quantifying the SWR performance of an antenna. Maybe useful for quick checks of an antenna. I’ll need to find someone with a good working antenna analyzer that I could use to compare to this one.
An examination of the innards of the MFJ-208 antenna analyzer didn’t reveal any obvious problems other than the messed up variable plate capacitor.
Everything else inside looks pretty clean.
With a pair of needle nose pliers and some very gentle pressure, I was able to bend the plates of the variable capacitor back to where I thought they should be. Both plates are parallel to each other now and don’t hit each other when rotated.
Now I just need to put everything back together, add power and test it out.
Spent some time going over the innards of the MFJ-207 antenna analyzer I picked up and doing some research to figure out what kind of rotary switch I’ll need to replace the existing messed up one with. I think I’ve found the correct replacement switch (a Lorlin CK1025 rotary switch).
Everything else inside looks in decent shape as far as I can tell. I haven’t tried to test all the individual components yet. No leaky/bulgy capacitors or burn marks and all the soldered connections seem solid. Aside from the rotary switch I’m not seeing anything else wrong with it.
Now to go over the MFJ-208. I don’t know if I’ll be able to find a variable plate capacitor to replace the existing one, but I might be able to fix it up so that it works the way it should.
The SoftRock SDR radio kits I ordered arrived in a little box yesterday. The SoftRock Lite II receiver and the SoftRock Ensemble RXTX kits I got both contain a lot of bits and pieces to put onto relatively small boards.
The SoftRock Lite II kit.
The SoftRock RXTX kit.
It will be a little while before I’m ready to tackle either of them. The receiver kit looks like it will be the easiest to start with. There are a few SMT components to put on, but not as many as the RXTX kit.
While browsing radios on ebay, I came across a couple of MFJ antenna analyzers: an MFJ-207 and MFJ-208.
They were both being sold as “For parts” and the person selling them wasn’t able to test them. From the description and the pictures that were posted, my expectations weren’t very high. The price was pretty low, and I figured if they worked I’d have a couple of antenna analyzers for pretty cheap and if they didn’t, I’d have an interesting project on my hands that I could learn something from.
They arrived in the mail today and I had a quick look inside both of them. Off the bat the 207 is going to need a new band selector dial. It looks like it’s supposed to be a one of those multi-position switch knobs, but if it was it isn’t anymore. On the 208 it looks like a new variable plate capacitor is in order. I’m no expert but I’m pretty sure the plates aren’t supposed to touch when the knob is turned. I’ve also never seen a variable plate capacitor with just two plates (one moving, one stationary).
I’ll have to spend more time and go over them more closely, but if these two things are all that’s wrong with the two analyzers, then this should be a pretty easy refurb project for me (provided I can find the parts). Fortunately the manuals for both of them are available on the MFJ website, and the 207 manual even has a schematic in it.
This should be interesting. Pictures to follow