Dave Richards AA7EE

August 2, 2011

The Messiness of Home-Brewing and The Echolink QRP Conference

Filed under: Uncategorized — AA7EE @ 6:09 am
Tags: , , ,

The previous post felt like a triumphant one. I built N1BYT’s WBR Regen, housed it in an enclosure I also made myself and it worked very well. It was one of those home-brew projects that turn out exactly the way you’d hoped it would.  The number of positive comments received was quite overwhelming and to be honest, I think the receiver looked a little better in the photos than it does in real life. I can promise you that I didn’t use Photoshop though – those pictures were almost straight out of the camera – just a little adjusting of levels and a tiny amount of sharpening applied. I even received positive feedback from Rich Arland K7SZ and Daniel N1BYT himself.  It was very encouraging, and I was so impressed by the performance of this simple receiver that I began work on another one, intended for general coverage. I did the calculations, wound 42 turns of wire on a T68-6 and figured I should be able to get something in the region of 3.5 – 12.5MHZ coverage when tuned by a pair of MVAM108 varactors.

Building started off well:

I then finished off the regenerative detector and before building the audio amp stages, fed the audio into an outboard amp, whereupon the trouble started. I’m pretty sure that I’m getting regeneration, because I can hear the onset of hissing as I adjust the regen pot.  Also, when I touch the coil, the hissing stops, indicating that the frequency of oscillation is changing, thus altering the point of onset of regeneration – or even ceasing oscillation altogether, so I’m pretty sure that means it is oscillating.

But I’m not receiving any signals and I’m not sure why. I haven’t been successful in connecting a frequency counter to the receiver.  I did hear of someone who was able to couple a WBR regen to a frequency counter by way of a coil placed near the WBR’s coil, but this hasn’t worked for me. Attempting to connect the counter more directly just stops the oscillation.  I’m wondering if the varactors are working, and if I could measure the oscillation frequency of the regenerative detector I might be able to ascertain this.

To be honest,  I’m a bit burnt out.  I think I’m going to carefully place this second WBR regen in a box somewhere and maybe come back to it some other time. Home-brewing can really frazzle you and take over your life if you let it. Just ask Jason NT7S.  Jason has been diligently working on the CC-40 and CC-20 transceiver for a while now. He’s had a number of setbacks, none of which have gotten the better of him, though they have cost him much time and I’m sure a great deal of stress. If you follow him on Twitter, you’ll have some idea of what he’s been going through.  My setback with the second version of this regen pales in comparison to what Jason has been experiencing. He designs circuits from scratch, while I merely copy other people’s. There is a world of difference. I’ll bet that anyone who designs their own circuits can understand what Edwin Armstrong went through.  Building your own stuff is a messy business, so I can’t begin to imagine how much messier designing your own stuff is.

In other news, I joined the Echolink QRP Conference on Sunday. This is a weekly net for QRP’ers that meets on Echolink node 140904 every Sunday at 9pm EST. They’re a friendly bunch of folks, and I had the fun of realizing that one of the participants in the net, John NG0R,  is on my blogroll. The QRP community is a small world. If you’re a QRP’er, you might want to try joining them.  If you don’t want to talk, you can always type “.lurk” in the chatbox and you don’t have to participate – you can just listen.

So that’s it.  I’m feeling a bit beaten down by my unsuccessful project. I am missing having general coverage in the shack and am wondering what to do about that.

 

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3 Comments »

  1. Bummed that I missed you on the QRP conference. To be honest it hasn’t interested me much the last few times that I checked in, but I always enjoy hearing NG0R and it would be great to hear you as well.

    I may not be beat down by my failures, but I feel like I’m getting damned close at times. Not sure if the universe is trying to teach me a lesson…and if it is, then which lesson is it? Well, expect a resolution one way or the other within the next few weeks.

    72,
    Jason

    Comment by Jason Milldrum — August 2, 2011 @ 6:37 am | Reply

  2. You probably tried this, but… Since a toroid concentrates most of the field in its core, bringing a coil close to it to work as a pickup might not do the trick. Did you try a loop through the center? My other suggestion would of course be an oscilloscope, but I suspect you would have tried that if you had one handy.
    Good luck with this build, hope you figure out the problem. I very much enjoyed reading your last post about the enclosure build, and your spotless, orderly construction is an inspiration. My own efforts have been getting better but are still quite messy by comparison.

    Comment by Robert AK6L — August 2, 2011 @ 9:21 pm | Reply

    • Robert – I’m embarrassed to admit it, but I didn’t think of that. Sometimes I’ll put a lot of energy into figuring out overly complex solutions while ignoring the obvious. Thanks for the suggestion and it worked! I have now ascertained that the oscillator is indeed oscillating, but it seems to be covering a relatively narrow band around roughly 5.3 – 5.7 MHz. I can hear the trademark regen hissing and what sounds like general radio atmospherics, but I’m probably not hearing anything because there’s not much to hear on those frequencies.

      Comment by AA7EE — August 3, 2011 @ 2:55 pm | Reply


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