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Sunday, July 12, 2009

Taming the Beast: Progress on the One FET Regen Rig

I went back to work on the ET-1R, my relay-based version of the single FET transceiver (check the index on the left under Minimalist Radio for more on this). The contest this weekend (was it CQ WW DX?) gave me plenty of signals to tweak the receiver with. I finally got the RX in the right freq range, and I have a nice banset/bandspread arrangement with two variable caps. I attacked the dreaded hand capacity issue via the use of non-conducting attachments to the capacitor shafts (one is the cap from a pen, the other is a piece of wood from a clothes pin).

The slaughter of innocent MPF-102s has ended (some victims are visible on top of the SPRAT). The culprit was NOT voltage spikes from the relay coil (although that might have contributed). Instead, what was happening was that I had the gate voltage set way too high on the transmit side. Whenever I powered up the rig, it was for an instant in the transmit mode (before the relay kicked in). The high voltage jolt on the gate was enough to kill the FET.

You can see the transmitter tucked in behind the relay. It moves my SWR meter on key down, so I'm confident I can get at least one QSO (perhaps across Rome) with this rig. Then, I intend to retire it. It will probably be a few years before I forget the pain and decide to build another minimalist regen rig.

3 comments:

  1. Oh, you may retire the ET-1R but that won't be the end of it, because you've now entered.......

    The Michael Rainey Zone.

    Next thing we'll hear is that you've constructed a transceiver using nothing but Germaniu diodes, a paper clip and some lemons.

    Where does this all end? The stone knives and bear skin are sure to follow........:-)

    73 from somewhere south of Neverland.......Steve Smith WB6TNL

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  2. Looks like a real homebrew project. I can just imagine cold nights, a straight key in hand, and working DX with this thing.

    And then the reality that you have faced with this rig ...

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  3. Bill:

    I can feel your pain when it comes to Regen radios. Personally, I have built more than a couple of them and each radio seems to have their own personality. I the first successful one I built at 16 and it was a Radio Shack one because I could not afford a DX-160 shortwave - this was the late 70's when the cold war was still raging strong and it seemed like every country had a shortwave broadcast station - one time tuned into radio Moscow and they were talking about the preparation of reindeer meat - you could tell you were listening to radio Moscow because announcers always spoke with flawless English pronunication with no accent whatsoever -very spooky. Anyways you might want to check out the Radio Board forums thread - they sponsor the "1AD" contest where members try to build a one active device radio receiver and compete in a listening contest to judge in performance. This thread is a discussion on the one FET regen circuit http://theradioboard.com/rb/viewtopic.php?t=1431&postdays=0&postorder=asc&start=0
    Love your podcasts keep up the great work.

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