Matching a Mazzoni Stealth Ant?

Cirrus Secure

Bottom line: I like the loop -- a lot. Using 50 watts, I've been logging +6000 mile "QSO's" via FT8 -- Trans-US/Canada, SA, and trans-Atlantic including the EU, Ukraine, Russia, etc. No SW Asia, Australia, or new Zealand yet. The plane of the loop is oriented E-W but the azimuths I log are all over the compass.

I usually follow the grey line, starting on 17m at about 1600 edt and work my way down to 40m by 2200 edt.

In short, the coax from the loop is connected to it's tuner at the OP atop the Flex. A 3 foot length of RG8X connects the loop tuner to ANT2 on the Flex.

For photo's of the set-up and links to Mazzoni info see: https://www.qrz.com/db/KE2KQ 

I get a pretty repeatable <1.5 VSWR on 40 thru 10 (as measured on the Flex) by:

(1) Auto-tuning the loop.The loop's tuning is initiated by it's own USB connected keypad. Step (1) almost always gets between 1.2 and 2.5 (as measured on loop's auto-tuner). I can see the loop tuner's carrier at work on the Flex pan display. I ends up right where it should.

But then I have to (2) auto-tune the Flex. When the Flex ATU is bypassed it measures an off-the meter VSWR. So it pulls my tx power down to nothing to protect itself. 

Often I have to iterate on (2) several times and get either very high or <1.5 VSWR (as measured on the Flex). It's like rolling dice! :-) But eventually I get to a very low VSWR.

I'm using a new, continuous, 50 ft run of RG-8X made up by DX Engineering connecting the loop with it's tuner (which is sitting atop the Flex). The coax and loop tuner control pair are just laying on the lawn. The coax exits the tuner at right angle to the plane of the loop.

I'm learning how to use Flex's 'profiles' to try and capture all it's many settings in one place hoping that will eliminate the hit or miss part with the Flex ATU. No joy with that so far. The Flex ATU memory is on.

What's a Flex'er to do?

73,
Tom KE2KQ

N8AUM

Hello Tom, Double check ur new coax. About 6 months ago my brother was having problems and it was a bad coax from the same place u got urs. Good luck !
73 N8AUM  Vidas

Bob Perkins

Tom,  I agree with N8AUM.

I, also ran into problems using DX Engineering coax about two years ago.  I attached a brand new 75 foot run of LMR400 with factory installed PL259 connectors onto a 40/75 meter dipole, and the SWR would never come down below 4:1.  A continuity check showed the coax was fine, but it never did function correctly with my antenna. In an effort to make it work, I ordered ABR coax from a different supplier, and it worked perfectly.  DX Engineering let me return the coax, but told me there wasn't anything wrong with it, so rather than returning my money, they would only issue a credit, which could only be spent with their store.  Your problem may not be your new coax, but feed lines can cause strange things to happen sometimes.

Cirrus Secure

Thanks guys. I have at it from that angle. 73, Tom.

Patrick

I don’t know how much power you use when auto tuning the radio. But I think if you use just 10 watts, the protection circuit might be happy and give you a good tune.  

Patrick

Another suggestion would be to put a dummy load at the antenna end then run your max power.  Also the length of the coax as a multiple of wavelengths may not be proper for the antenna and for the tuner to operate properly within that frequency range. 

N8AUM

Hi Pat, the "Auto Tune" is fixed at 10 watts. Maybe theirs a secret Moose hand shack that lets you change it but I have yet to find it. I personally think you dont need that much power, 5 watts would probably enough. Maybe their is settings on earlier versions ?

Patrick

The Tune slider would adjust that and is remembered in persistence, unless it is coming from outside control.  

N8AUM

Yes Pat you can adjust the "Tune Power" with slider but NOT the amount of power used when you use the "Auto Tune". I hope I am wrong but I have yet to find how to adjust power if I click Auto Tune. Hope that makes sense ?

Patrick

I was talking more about external devices being tuned like external antenna tuners.  My radio uses some where in the order of 5 to 10 watts which seems to change as the radio tunes.