Smoke, New Ones and QRO – 2011 ARRL DX Contest (CW)

Even without personal experience, we all know that QRO is more high-maintenance than the 100 watt world. I knew going into this that my old (but new to me) AL-811 might not handle the duty cycle of a 48-hour contest – my plan was to back it down to 300 watts at the first sign of excessive heat.

Little did I know that it would be my 600-watt autotuner that would fill the room with that acrid aroma of overheated electronics.

Up to now my only use of the amp has been in pile-ups, ie brief inputs of my dot-filled callsign. No sweat – easy on the amp and the tuner. Except for a brief 20-minute run of JA’s on 40 meters this morning, I operated Search-n-Pounce for the duration of my activity in the contest.

It was that 20 minute exception that smoked a torroid in the tuner.

Opening the tuner revealed what you see in the photo. Tests showed that L3 gets too hot to touch, even at 100 watts. A few CQs at 500 watts has it hotter than a $3 pistol, yet the adjacent torroids are as cool as cukes. Three of the relays also get pretty warm – too warm to simply be convection heating from L3.

What to do…? I’ll email LDG tomorrow. Reviews on eHam and elsewhere give high ratings to their customer service. The solution may simply be for me to add a few feet of feedline to change the impedance seen by the tuner on 40 meters, however, that might just move the problem to another band.

I’m thinking that if the tuner is rated for 600 watts, and 500 watts smokes a component, then the tuner has a problem. I’m also thinking that a simple replacement of the tuner (with no other changes) will result in the same problem…

On to the contest:

Apart from the inductor smoke, operating at 500 watts makes things so much easier and certain.

Most of the DX stations used a kilowatt. Before, with 100 watts on my end, I would often be asked “AGN?, AGN?” after sending my part of the exchange, particularly if the DX was weak on my end. In this contest, there was very little of that – I was heard just fine, first time around on the weakest stations that I called.

That was the Big Difference in this contest for me from all prior efforts. I got through…quickly, easily and with no fuss. Then on to the next guy.

My main worry – okay, “worry” is too strong a word – going in to this was that, somehow, even with a QRO power level, I’d fail to top my last years’ score and end up feeling like an idjit. Particularly with the recent sunspot party going on in the ionosphere.

I needn’t have worried about that. With the exception of 10 meters, there was plenty of activity from all continents. Even 10 meters was better than fair.

Highlights?

  • Being called by VP8NO in the Falklands. Yeah, he called me!
  • Getting Honduras (HQ9R) on 160. T’ain’t far, but I don’t have an antenna for 160. My 31st country on that antenna-less band.
  • Getting DU on 40 meters; KH0 on 80 meters.
  • JH1ARZ on 40m and NP4Z on 10m – both were QRP

The contest ends in two hours but, as for me, stick a fork in me – I’m done.

Here’s the numbers:

(Last year: 138,159 points)

1722 QSO points X 242 mults = Total Score of 416, 724

K3, AL-811, 80m dipole

Band QSOs Countries
10 34 21
15 181 62
20 122 62
40 162 56
80 74 40
160 1 1

See you in 2012…

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  8 comments for “Smoke, New Ones and QRO – 2011 ARRL DX Contest (CW)

  1. February 21, 2011 at 2:53 am

    Hi John, great contest with great score. You made some nice DX. So unfortunate you smoked the antennatuner. Could be a design error, but it could also be something else. Hope you can work it out. 73, Bas

  2. February 21, 2011 at 3:31 am

    The specs of ATUs claim the losses are around 5 to 10 percent but that is with a 50 ohm load. I’ve never seen an attempt to measure losses into different mismatched loads but I expect the results would be an eye opener. My KAT2 would find a 1:1 match on 80 and 160 with a small attic loop whose real SWR was so high as to be unmeasurable. I never heard anything on those bands with it. Kinda makes you wonder where all the RF went?

  3. February 21, 2011 at 4:45 am

    Yes John, you got through…quickly, easily and with no fuss.
    My limited experience with QRO and tuners is that QRO + wild impedances = problems. My MFJ-998 handled a modest kW quite OK as long as the impedance was not too extreme. But nothing beats a matched antenna, so I did that and sold the tuner.
    Thanks for calling me (as OQ5M) on 20m yesterday.
    73 / CU de Franki ON5ZO

  4. February 21, 2011 at 6:18 am

    Thanks for the comments, folks.

    A few years ago, an article in QST compared the losses of several manual tuners under various degrees of mis-match. A model from TenTec came out ahead – I wish they’d do a similar test of auto-tuners, including all the built-ins now common.

    Thanks for the contact, Franki – I didn’t work too many of your countrymen but did work the ham-famous ON4UN on 20m – what was he doing way up there?! And a great write-up on your website, complete with a reference to Forest Gump!

  5. John N0EVH
    February 21, 2011 at 5:32 pm

    John,

    Yes, impressive with your go at the DX contest. Also saw your comment on the K3 on the reflector, it is enjoyable to run the K3. I did not have time to run the full test, so picked a few hours and went searching for some entities to pick up with QRPp. I am always amazed at the end of a long contest when Q’s are harder to find for the big gun stations, how well they can hear. I was picking up KW stations with 0.1 to 0.5 watt out from my 80 meter loop. If I caught them in a lull and sent my call in the clear they usually got it the first go. Always a thrill to hear your call sign come back to you from the other side of the world.

    Great operators, great stations and great fun.

    73 John N0EVH

    • February 21, 2011 at 5:57 pm

      There certainly were some loud stations, particularly from Eastern Europe – fortunately for us, they could hear as well as be heard. Conditions being what they were I think a lot of ops will have higher scores than they may have expected.

  6. February 24, 2011 at 5:00 pm

    hi John good score here 385 Q S&P you are not in my log .. but i had to miss our best 15m time Saturday I choose to run low power. The east EU/ UA stations impressed me too. They seem to have better propagation. And top setups. They seem to work easy >9000km to USA. Translated to my location that would be pileups of Westcoast… But only a few CA worked here.
    73 PA0O

    73 Jaap

  7. Don..
    March 7, 2011 at 9:19 pm

    its called Core saturation!! Too much power for the size of the core. Its much better if the manufacturer uses higher wattage cores than needed to handle the calculated load. Just cost a few dollars more..
    Its kinda like power resistors, if you need a 10 watt one, use at least a 20 watt one or even larger then don’t worry about over heating.

    73, Don K5DUT

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