So your looking for a new tuner, antenna that is, and you figure that you should try and search eBay for a deal.  eBay in the infancy was pretty good.  Lots of honest people selling their used or barely used stuff.  And of course the more you make the more Stuff you need!…Wait i sound like George Carlin.


So I needed a new Antenna Tuner because my AEA AT-300 isn’t sufficient to handle my Ameritron 811H Linear Amplifier.  How do I know that, cause I smoked the Forward power sensing diode in it..Not too much smoke, but I turned to the tuner, and all I see is deflection of the SWR pointer…Ok that isn’t good.

Hunt up the schematic on line…and of course you can’t read the part numbers of the components, so hunting around in my other STUFF, I find a home made PWR?SWR meter, open it up, strip out the potentially good diode and try and disassemble the AT-300..Ha that was fun, they mounted the board directly over the chassis mounted connector on the back panel…of course  the SO-239’s had lockwashers and nuts on the screws with about 1/4 in clearance to get at them.

Got them off, found that the diode was blown open, replaced it…and all is well with the AT-300…

I still needed a Tuner that would handle the AMP…so I bid on several auctions, lost them all.  Until…

There was a MFJ Versa Tuner V (MFJ-989C), which would handle 3KW and had a built in Dummy Load…so I watched and waited..until the last 1/2 hour…put some odd numbered value in there, and hoped for the best.  I got it for 177.00 which wasn’t too bad considering they cost about 2x that amount.  Thought the 25 bucks for shipping was a bit much but oh well.

To make a long story longer..When I received the Tuner, the description wasn’t quite as it was stated, but not bad…Except the Meter lamp was burned out, the Inductor Knob wobbled a bit and squeeked like hell !!..Ended up taking it apart, replacing the wheat lamp with a bright white LED, cleaned up the front panel lubricated the gearing after cleaning the shafts…and now all seems well…

Earlier when I first got it, I couldn’t get it to tune on the Balanced line 450 Ohm NVIS Delta Loop that I’ve been using for about 4.5 years.  Which I thought was strange…Of course the Jumper that was needed on the back panel wasn’t installed, jumpered the other 2 standoffs and that worked.

I also run a HexBeam that is good from 20M – 6M.  Doesn’t like 30M which i accidently had the rig on trying to get the ‘balanced line’ working…OOPS…Blew out my Digital SWR /WATTMETER MFJ 826B…display worked ok, but no readings of FWD/Reflected signals..

Nutz…blew another diode in this one !!..of course I didn’t have what they recommended, so in the end replaced it, got it working, but not calibrated real well…even though i followed their instructions. They told me I could send it in if the diode didn’t fix it..I might..



About vince320

N2AIE Amateur Radio Operator / Builder

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