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  • > The best thing you can do, is using a cascode circuit between the regenerative stage and the detector stage, a cascode circuit has a much wider bandwidth than single BJT amplifier stages. A dual-gate MOSFET, then. A dual-gate MOSFET is two single-gate MOSFETs in cascode. Just as, in effect, a vacuum screen-grid tube can be synthesized by two triodes (or a triode and a tetrode...
    david.newkirk@... Nov 8, 2016
  • Bernd wrote: > IMO this is exactly, what this Global Span Receiver is doing, it is a "HiFi Regenerative Receiver". ...for AM. Cool. Too bad Radio Netherlands has had no English transmissions since 2012. Might want to -update the 14-year-old preamble a bit, as many of yesterday's powerhouse, worth-listening-to international shortwave stations have since abandoned the language. Best...
    david.newkirk@... Nov 7, 2016
  • Ed wrote: > Then again, a lot of beam tetrodes will work for that purpose without much effort, as long as you put some effort into properly loading them. True, but in the 12A6 several useful factors come together: 1 It's metal (I have seen later, 12A6GT variants) and therefore inherently well-shielded with Pin 1 connected to common 2 It's heated at 12.6 V, and therefore its heater...
    david.newkirk@... Nov 5, 2016
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  • Mike wrote: > There's that infamous floating diode product detector again. Any comments? Was it actually tested in the "Miser's Dream"? Yes. Here's what By had to say about it: "The product-detector circuit is an adaptation of one devised by Don Norgaard ("Single Sideband Reception," _G.E. Ham News_, November-December 1948). In the original with 6H6 twin diodes it looked...
    david.newkirk@... Nov 4, 2016
  • Hue wrote: > i find myself with two 2215 kHz crystal filters, 3 kHz and 250 Hz. I have the SSB crystals for it too but their freqs make for a very tight SSB bandpass. I have the boards pulled and i can supply schematics with this. Bet those filters came from Blackhawk Engineering of Janesville, WI. 2215 was used as the first IF in one or more of the NC-30x receivers, and Goodman...
    david.newkirk@... Nov 3, 2016
  • Hue wrote: > However David Newkirk pointed out that the driving gate of the MOSFET goes to ground, so the source-to-diode output is actually a source- follower with...
    david.newkirk@... Nov 1, 2016
  • Don wrote: > I followed the osc loosely but built the 4 tube PA from the heart. I tried a lot of different keying methods but settled on this one.Old Reliable I guess(All cathodes or B neg keying) Yes, the original Hadlock circuit had us keying just the amplifier screen--can't have one side of the key grounded then, and there's quite a backwave. The 6BE6 is a good oscillator-tube...
    david.newkirk@... Nov 1, 2016
  • Argh, and it was written by Hadlock, not Bacon, of National. Sure wish we could get that little black-wrinkle steel box new nowadays...
    david.newkirk@... Oct 31, 2016
  • I wrote: > Dana Bacon's "A Versatile Portable-Emergency Transmitter" on page 9 of July 1941 _QST_ Oh, forgot to add that I've got an HTMLized reprint of Bacon's article at http://dpnwritings.nfshost.com/ej/w1ctw_tx/ . And I must add coverage of the Longfeller below the subhead I've long had in place for it in my Boosted Pierce writeup at http://dpnwritings.nfshost.com/ej/boosted...
    david.newkirk@... Oct 31, 2016
  • Don wrote: > I have been playing with a longfellow of my own concoction. Five 25L6 tubes bought for $5 each NOS , some maple straping , an old ceramic trimmer cap and a handful of parts.. That's a classic -- love the finished slat-board construction, complete with side pieces. (The Longfeller was the subtitle name of "A Beginner's Two-Stage Transmitter" on page July 1946 _QST_, a...
    david.newkirk@... Oct 31, 2016