View Single Post
  #16   Report Post  
Old April 24th 09, 03:26 AM posted to rec.radio.amateur.homebrew
Bill M[_3_] Bill M[_3_] is offline
external usenet poster
 
First recorded activity by RadioBanter: Feb 2009
Posts: 35
Default XTAL Radio Receiver Circuits

Unca Pete wrote:
"Bill M" wrote in message Basically true but in
fairness to the folks who have never tried it you
MAY get some additional volume on a reasonably strong local station. You
shoot your selectivity and ultimate sensitivity in the foot, though,
because of the extra loading on the tank. ie, not a DX set.

There's one circuit floating around that uses a dual center-tapped tank
(so to speak) with a diode on each side and their outputs are combined.
One fellow said it worked pretty well as a workaround for the loading
concern. Still not a DXers set but better than attempting a voltage
doubling detector.

-Bill


Basically a fullwave rectifier?

I'd still opt for a quality matching transformer, and go for the max.
volume if that is the goal.

Pete


Yabbut...max volume isn't the same as max sensitivity in DX sets. Its
only one part of the scheme. I used the term "house of mirrors" in all
seriousness. You upgrade the xfmr to a certain point then you need a
diode that performs to that level and then you need to upgrade the tank
to that level...and so it goes. Thats why high performance crystal
radios are so fascinating. And they really are. I've logged Brasilians
at 3500 miles away.

The guys who are top-scoring in the annual 'test' are logging 100-200
stations. You get there with selectivity and sensitivity...and patience
with good ears. No doubling, tripling, quadrupling circuits are in the
mix. They don't pan out. Its all well documented.

-Bill