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Author Topic: AEA VIA HF Analyzer problem  (Read 1003 times)
N3OYO
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Posts: 113




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« on: December 20, 2006, 03:10:10 PM »

I have an AEA Analyzer (just been calibrated)

Here's the problem: (SWR checked @ antenna-An R6000))

The AEA VIA Analyzer reads around 5-1 SWR on 20m & 17M. 10M & 6M reads OK (1.3 to 1.6 to 1). Was OK when I tuned it with the meter a few weeks ago??

My 746 Pro, (with tuner off of course), see's (for what it's meter's worth) maybe 1.2 to 1 or thereabouts on those bands, transmits full power, etc with no problems.(See's no high SWR)

Doe anyone know if these are so sensitive that there could be some kind of "interference" problems causing it to seemingly read a high SWR? My 6M loop on the roof is flat (1.1-1), and again the 10M & 6M bands read OK on the Cushcraft R6000.

My Xmas gift (next week) is a new Daiwa SWR/Watt Meter. I'll have something to reference then I guess..Anyone any theories?
                Thanks in Advance!   73' N3OYO
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W4BQF
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« Reply #1 on: December 21, 2006, 02:56:34 PM »

There is one of two things wrong here. Either your explanation is poor or you technical knowledge of what you are doing, needs some help!

You never check the accuracy of an SWR meter/analyzer using an antenna. And you need a known reference. If you check your meter/analyzer into a known good 50 ohm load, (known good throughout the HF spectrum), the you know for sure the reading you get when you check your antennas with the analyzer is correct.

Your 756 is NOT an antenna analyzer! You bought that to be your communication device. The SWR bridge/circuit is there to give you an estimated SWR reading of the load it's operating into.

If you back up and get yourself a good 50 ohm load for a reference, then if your analyzer reads a low (1:1) SWR across the HF bands, then you have a 'calibrated' instrument with which you can check your antenna systems. Then you can compare the reading you get with your 756, which will tell you or give you some indication of how accurate the SWR bridge in your 756 is.

Good luck and Mri Christmas....


Tom - W4BQF
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N3OYO
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Posts: 113




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« Reply #2 on: December 21, 2006, 05:57:04 PM »

Thanks for the reply..No..I wasn't checking/comparing the Analyzer using the rig's meter..I was just commenting that the 746 see's a LOT lower (1.2 to 1 vs 5 to 1 on Analyzer)..If it was as high as the Analyzer indicates..the 746 would fold back power a lot..as it is..it work's fine. I thought it was out of cal (analyzer) 3 weeks ago...& sent it to AEA..they calibrated it (said there was no problem) & got it back yesterday (I should've mentioned that I guess)It show's the same. I don't have (at the moment) a 50 ohm ref load..but I was deducing, from what I've seen with what I have, maybe there was local high area RF (Maybe some kind of interference, etc) where I live & the meter saw it as a reflection...I'm aware the SWR indicator on the rig is just sort of a reference...Thanks...
(A Merry Xmas to all)
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N3OYO
Member

Posts: 113




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« Reply #3 on: December 25, 2006, 10:19:47 AM »

Update:  Ok...for Xmas I just got a Daiwa 801HP SWR/Wattmeter..and it TOO show's a low SWR on 20M & 17M..(1.2 to 1)..and the AEA Analyzer show's 4 to 1 or so..so my rig AND my new SWR meter both show low SWR..while the AEA VIA Analyzer show's a high SWR...Any ideas..

and..Merry Christmas!
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NS6Y_
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« Reply #4 on: December 25, 2006, 10:23:44 PM »

OK the first thing you want to do is get a reference dummy load or terminator to test your analyzer against. Let's see, I use an HP 11593A. That's a lab quality BNC terminator, very flat to a GHz or so. Put that as directly onto your analyzer as possible, it should read flat 1:1 across all the bands. This little terminator is the size of a tie-tac, I have a large commercial dummy load made by RadialWave or someone, also dead flat, and as big as a breadbox - the key is, commercial or lab quality. Some ham-grade dummies will read 1.2:1 or 1.3:1 and are not quite as good an exact check'r. Make sure the analyzer's working right first!

Then, you're ready to measure your ant. First thing, is you really don't want to be in the presence of strong RF fields. All the analyzer is capable of seeing is RF going out from it and coming back in. RF coming in from some other transmitter can fool it, and if bad enough fool WITH it. You can damage the diodes in the input circuit.

So, first you've verified that your analyzer works with a good terminator/dummy load, you're set up where/when no one's transmitting near you, now you can measure your antenna. Not only can antennas have more than one low SWR point, there can be funny things going on like bad connections, "iffy" coax, etc. Connectors can get loose, water can get in, etc. I once had a discone break in HALF, right in the thick part in the middle. It's a tough world out there if you're an antenna. So not only is there the basic antenna tuning aspect to this, there's always in the background the possibility that connections may act up, etc.

now for the AEA itself - make sure the batteries aren't run down too far, the unit may act oddly if it's getting just marginal voltage. The clips that hold the batteries eventually wear out and when that happens it's not pretty, I've seen it. I've read in reviews of the AEAs that those input diodes can get damaged and that can cause odd operation. If you're having real doubts, you can always send it back to AEA for a refurb.

I'm a real fan of graphical analyzers myself, and sooner or later will probably get an AEA for VHF.
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NS6Y_
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« Reply #5 on: December 25, 2006, 10:27:09 PM »

Hmm, looking at your posts there.... the AEA's showing a high SWR on certain bands, which you've verified closely enough just isn't there. Sounds like you may have a little hardware problem with the AEA, or a software problem, and may want to talk to AEA, go through a hard reset, few things like that.

Keep in mind there's a good chance AEA's not really doing any business until after the 1st. A lot of tech companies just take 2 weeks off for Xmas and new year's.
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